Merge branch 'release/materials_featurette' into release/gltf-maint2

101 files changed, 5240 insertions, 653 deletions

diff --git a/indra/newview/CMakeLists.txt b/indra/newview/CMakeLists.txt
index 7a70d0b6e6..04d3b64d5c 100644
--- a/indra/newview/CMakeLists.txt
+++ b/indra/newview/CMakeLists.txt
@@ -310,6 +310,7 @@ set(viewer_SOURCE_FILES
     llgiveinventory.cpp
     llglsandbox.cpp
     llgltfmateriallist.cpp
+    llgltfmaterialpreviewmgr.cpp
     llgroupactions.cpp
     llgroupiconctrl.cpp
     llgrouplist.cpp
@@ -519,6 +520,7 @@ set(viewer_SOURCE_FILES
     llrecentpeople.cpp
     llreflectionmap.cpp
     llreflectionmapmanager.cpp
+    llheroprobemanager.cpp
     llregioninfomodel.cpp
     llregionposition.cpp
     llremoteparcelrequest.cpp
@@ -963,6 +965,7 @@ set(viewer_HEADER_FILES
     llgesturemgr.h
     llgiveinventory.h
     llgltfmateriallist.h
+    llgltfmaterialpreviewmgr.h
     llgroupactions.h
     llgroupiconctrl.h
     llgrouplist.h
@@ -1158,6 +1161,7 @@ set(viewer_HEADER_FILES
     llrecentpeople.h
     llreflectionmap.h
     llreflectionmapmanager.h
+    llheroprobemanager.h
     llregioninfomodel.h
     llregionposition.h
     llremoteparcelrequest.h
diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index 3d43a20c21..1a614062d9 100644
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -9153,6 +9153,17 @@
       <real>0.00</real>
     </array>
   </map>
+  <key>RenderMirrors</key>
+  <map>
+    <key>Comment</key>
+    <string>Renders realtime mirrors.</string>
+    <key>Persist</key>
+    <integer>1</integer>
+    <key>Type</key>
+    <string>Boolean</string>
+    <key>Value</key>
+    <integer>0</integer>
+  </map>
   <key>RenderScreenSpaceReflections</key>
   <map>
     <key>Comment</key>
@@ -10357,6 +10368,28 @@
       <key>Value</key>
       <integer>0</integer>
     </map>
+    <key>RenderHeroProbeResolution</key>
+    <map>
+        <key>Comment</key>
+        <string>Resolution to render hero probes used for mirrors, water, etc.</string>
+        <key>Persist</key>
+        <integer>1</integer>
+        <key>Type</key>
+        <string>S32</string>
+        <key>Value</key>
+        <integer>1024</integer>
+    </map>
+	<key>RenderHeroProbeDistance</key>
+	<map>
+		<key>Comment</key>
+		<string>Distance in meters for hero probes to render out to.</string>
+		<key>Persist</key>
+		<integer>1</integer>
+		<key>Type</key>
+		<string>F32</string>
+		<key>Value</key>
+		<real>8</real>
+	</map>
     <key>RenderReflectionProbeVolumes</key>
     <map>
       <key>Comment</key>
@@ -10781,7 +10814,7 @@
     <key>RenderTerrainScale</key>
     <map>
       <key>Comment</key>
-      <string>Terrain detail texture scale</string>
+      <string>Terrain detail texture scale (meters)</string>
       <key>Persist</key>
       <integer>1</integer>
       <key>Type</key>
@@ -10789,6 +10822,83 @@
       <key>Value</key>
       <real>12.0</real>
     </map>
+    <key>RenderTerrainPBREnabled</key>
+    <map>
+      <key>Comment</key>
+      <string>EXPERIMENTAL: Enable PBR Terrain features. Requires restart.</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>Boolean</string>
+      <key>Value</key>
+      <integer>0</integer>
+    </map>
+    <key>RenderTerrainPBRForce</key>
+    <map>
+      <key>Comment</key>
+      <string>Force-load PBR terrain if enabled</string>
+      <key>Persist</key>
+      <integer>0</integer>
+      <key>Type</key>
+      <string>Boolean</string>
+      <key>Value</key>
+      <integer>0</integer>
+    </map>
+    <key>RenderTerrainPBRDetail</key>
+    <map>
+      <key>Comment</key>
+      <string>Detail level for PBR terrain. 0 is full detail. Negative values drop rendering features, in accordance with the GLTF specification when possible, which reduces the number of texture binds.</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>S32</string>
+      <key>Value</key>
+      <integer>0</integer>
+    </map>
+    <key>RenderTerrainPBRScale</key>
+    <map>
+      <key>Comment</key>
+      <string>PBR terrain detail texture scale (meters)</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>F32</string>
+      <key>Value</key>
+      <real>4.0</real>
+    </map>
+    <key>RenderTerrainPBRPlanarSampleCount</key>
+    <map>
+      <key>Comment</key>
+      <string>How many UV planes to sample PBR terrain textures from. 1 is "flat", 3 is triplanar mapping (aka box mapping)</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>S32</string>
+      <key>Value</key>
+      <real>3</real>
+    </map>
+    <key>RenderTerrainPBRTriplanarBlendFactor</key>
+    <map>
+      <key>Comment</key>
+      <string>Higher values create sharper transitions, but are more likely to produce artifacts.</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>F32</string>
+      <key>Value</key>
+      <real>8.0</real>
+    </map>
+    <key>RenderTerrainPBRNormalsEnabled</key>
+    <map>
+      <key>Comment</key>
+      <string>EXPERIMENTAL: Change normal gen for PBR Terrain.</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>Boolean</string>
+      <key>Value</key>
+      <integer>0</integer>
+    </map>
     <key>RenderTrackerBeacon</key>
     <map>
       <key>Comment</key>
@@ -13719,6 +13829,17 @@
       <key>Value</key>
       <integer>2</integer>
     </map>
+    <key>UIPreviewMaterial</key>
+    <map>
+      <key>Comment</key>
+      <string>Whether or not PBR material swatch is enabled</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>Boolean</string>
+      <key>Value</key>
+      <real>0</real>
+    </map>
     <key>UIResizeBarHeight</key>
     <map>
       <key>Comment</key>
@@ -15634,7 +15755,7 @@
       <key>Type</key>
       <string>S32</string>
       <key>Value</key>
-      <integer>2048</integer>
+      <integer>1024</integer>
     </map>
     <key>max_texture_dimension_Y</key>
     <map>
@@ -15645,7 +15766,7 @@
       <key>Type</key>
       <string>S32</string>
       <key>Value</key>
-      <integer>2048</integer>
+      <integer>1024</integer>
     </map>
     <!-- End of back compatibility settings -->
     <key>teleport_offer_invitation_max_length</key>
@@ -16521,6 +16642,50 @@
       <key>Value</key>
       <integer>0</integer>
     </map>
+	<key>LocalTerrainAsset1</key>
+    <map>
+      <key>Comment</key>
+      <string>If set to a non-null UUID, overrides the terrain asset locally for all regions with material assets. Local terrain assets are not visible to others. Please keep in mind that this debug setting may be temporary. Do not rely on this setting existing in future viewer builds.</string>
+      <key>Persist</key>
+      <integer>0</integer>
+      <key>Type</key>
+      <string>String</string>
+      <key>Value</key>
+      <string>00000000-0000-0000-0000-000000000000</string>
+    </map>
+	<key>LocalTerrainAsset2</key>
+    <map>
+      <key>Comment</key>
+      <string>If set to a non-null UUID, overrides the terrain asset locally for all regions with material assets. Local terrain assets are not visible to others. Please keep in mind that this debug setting may be temporary. Do not rely on this setting existing in future viewer builds.</string>
+      <key>Persist</key>
+      <integer>0</integer>
+      <key>Type</key>
+      <string>String</string>
+      <key>Value</key>
+      <string>00000000-0000-0000-0000-000000000000</string>
+    </map>
+	<key>LocalTerrainAsset3</key>
+    <map>
+      <key>Comment</key>
+      <string>If set to a non-null UUID, overrides the terrain asset locally for all regions with material assets. Local terrain assets are not visible to others. Please keep in mind that this debug setting may be temporary. Do not rely on this setting existing in future viewer builds.</string>
+      <key>Persist</key>
+      <integer>0</integer>
+      <key>Type</key>
+      <string>String</string>
+      <key>Value</key>
+      <string>00000000-0000-0000-0000-000000000000</string>
+    </map>
+	<key>LocalTerrainAsset4</key>
+    <map>
+      <key>Comment</key>
+      <string>If set to a non-null UUID, overrides the terrain asset locally for all regions with material assets. Local terrain assets are not visible to others. Please keep in mind that this debug setting may be temporary. Do not rely on this setting existing in future viewer builds.</string>
+      <key>Persist</key>
+      <integer>0</integer>
+      <key>Type</key>
+      <string>String</string>
+      <key>Value</key>
+      <string>00000000-0000-0000-0000-000000000000</string>
+    </map>
 	<key>PathfindingRetrieveNeighboringRegion</key>
     <map>
       <key>Comment</key>
diff --git a/indra/newview/app_settings/shaders/class1/deferred/avatarF.glsl b/indra/newview/app_settings/shaders/class1/deferred/avatarF.glsl
index 6ebe4ce251..c0607d0149 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/avatarF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/avatarF.glsl
@@ -33,11 +33,15 @@ uniform float minimum_alpha;
 
 in vec3 vary_normal;
 in vec2 vary_texcoord0;
+in vec3 vary_position;
 
 vec2 encode_normal(vec3 n);
+void mirrorClip(vec3 pos);
 
 void main() 
 {
+    mirrorClip(vary_position);
+
 	vec4 diff = texture(diffuseMap, vary_texcoord0.xy);
 	
 	if (diff.a < minimum_alpha)
diff --git a/indra/newview/app_settings/shaders/class1/deferred/avatarV.glsl b/indra/newview/app_settings/shaders/class1/deferred/avatarV.glsl
index bc0c11ec46..5cc2846156 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/avatarV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/avatarV.glsl
@@ -35,6 +35,7 @@ in vec4 weight;
 
 out vec3 vary_normal;
 out vec2 vary_texcoord0;
+out vec3 vary_position;
 
 void main()
 {
@@ -57,6 +58,7 @@ void main()
 	
 	vary_normal = norm;
 	
+    vary_position = pos.xyz;
 	gl_Position = projection_matrix * pos;
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/bumpF.glsl b/indra/newview/app_settings/shaders/class1/deferred/bumpF.glsl
index 35f483f633..a22c174349 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/bumpF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/bumpF.glsl
@@ -37,11 +37,15 @@ in vec3 vary_mat2;
 
 in vec4 vertex_color;
 in vec2 vary_texcoord0;
+in vec3 vary_position;
 
 vec2 encode_normal(vec3 n);
 
+void mirrorClip(vec3 pos);
 void main() 
 {
+    mirrorClip(vary_position);
+
 	vec4 col = texture(diffuseMap, vary_texcoord0.xy);
 	
 	if(col.a < minimum_alpha)
diff --git a/indra/newview/app_settings/shaders/class1/deferred/bumpV.glsl b/indra/newview/app_settings/shaders/class1/deferred/bumpV.glsl
index 3af2eab1e4..74319349f6 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/bumpV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/bumpV.glsl
@@ -23,6 +23,7 @@
  * $/LicenseInfo$
  */
 
+uniform mat4 modelview_matrix;
 uniform mat3 normal_matrix;
 uniform mat4 texture_matrix0;
 uniform mat4 modelview_projection_matrix;
@@ -38,11 +39,11 @@ out vec3 vary_mat1;
 out vec3 vary_mat2;
 out vec4 vertex_color;
 out vec2 vary_texcoord0;
+out vec3 vary_position;
 
 #ifdef HAS_SKIN
 mat4 getObjectSkinnedTransform();
 uniform mat4 projection_matrix;
-uniform mat4 modelview_matrix;
 #endif
 
 void main()
@@ -52,11 +53,13 @@ void main()
     mat4 mat = getObjectSkinnedTransform();
 	mat = modelview_matrix * mat;
 	vec3 pos = (mat*vec4(position.xyz, 1.0)).xyz;
+    vary_position = pos;
 	gl_Position = projection_matrix*vec4(pos, 1.0);
 
 	vec3 n = normalize((mat * vec4(normal.xyz+position.xyz, 1.0)).xyz-pos.xyz);
 	vec3 t = normalize((mat * vec4(tangent.xyz+position.xyz, 1.0)).xyz-pos.xyz);
 #else
+    vary_position = (modelview_matrix*vec4(position.xyz, 1.0)).xyz;
 	gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0); 
 	vec3 n = normalize(normal_matrix * normal);
 	vec3 t = normalize(normal_matrix * tangent.xyz);
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskF.glsl
index 6f3b94f734..e8ead91504 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskF.glsl
@@ -31,14 +31,20 @@ uniform float minimum_alpha;
 
 uniform sampler2D diffuseMap;
 
+in vec3 vary_position;
+
 in vec3 vary_normal;
 in vec4 vertex_color;
 in vec2 vary_texcoord0;
 
 vec2 encode_normal(vec3 n);
 
+void mirrorClip(vec3 pos);
+
 void main() 
 {
+    mirrorClip(vary_position);
+
 	vec4 col = texture(diffuseMap, vary_texcoord0.xy) * vertex_color;
 	
 	if (col.a < minimum_alpha)
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskIndexedF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskIndexedF.glsl
index e5f2af2c53..a07c892d8e 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskIndexedF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskIndexedF.glsl
@@ -28,6 +28,7 @@
 out vec4 frag_data[4];
 
 in vec3 vary_normal;
+in vec3 vary_position;
 
 uniform float minimum_alpha;
 
@@ -36,8 +37,12 @@ in vec2 vary_texcoord0;
 
 vec2 encode_normal(vec3 n);
 
+void mirrorClip(vec3 pos);
+
 void main() 
 {
+    mirrorClip(vary_position);
+
 	vec4 col = diffuseLookup(vary_texcoord0.xy) * vertex_color;
 	
 	if (col.a < minimum_alpha)
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseF.glsl
index 68fb8bf499..76776ede2c 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseF.glsl
@@ -32,11 +32,14 @@ uniform sampler2D diffuseMap;
 in vec3 vary_normal;
 in vec4 vertex_color;
 in vec2 vary_texcoord0;
+in vec3 vary_position;
 
 vec2 encode_normal(vec3 n);
+void mirrorClip(vec3 pos);
 
 void main() 
 {
+    mirrorClip(vary_position);
 	vec3 col = vertex_color.rgb * texture(diffuseMap, vary_texcoord0.xy).rgb;
 	frag_data[0] = vec4(col, 0.0);
 	frag_data[1] = vertex_color.aaaa; // spec
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseIndexedF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseIndexedF.glsl
index 93d561504e..b983acf657 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseIndexedF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseIndexedF.glsl
@@ -30,12 +30,15 @@ out vec4 frag_data[4];
 in vec3 vary_normal;
 in vec4 vertex_color;
 in vec2 vary_texcoord0;
+in vec3 vary_position;
 
+void mirrorClip(vec3 pos);
 vec2 encode_normal(vec3 n);
 vec3 linear_to_srgb(vec3 c);
 
 void main() 
 {
+    mirrorClip(vary_position);
 	vec3 col = vertex_color.rgb * diffuseLookup(vary_texcoord0.xy).rgb;
 
 	vec3 spec;
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseV.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseV.glsl
index 2402cc3b70..64230dc680 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseV.glsl
@@ -36,13 +36,16 @@ out vec3 vary_normal;
 
 out vec4 vertex_color;
 out vec2 vary_texcoord0;
+out vec3 vary_position;
 
 void passTextureIndex();
 
+uniform mat4 modelview_matrix;
+
 #ifdef HAS_SKIN
 mat4 getObjectSkinnedTransform();
 uniform mat4 projection_matrix;
-uniform mat4 modelview_matrix;
+
 #endif
 
 void main()
@@ -51,9 +54,11 @@ void main()
     mat4 mat = getObjectSkinnedTransform();
     mat = modelview_matrix * mat;
     vec4 pos = mat * vec4(position.xyz, 1.0);
+    vary_position = pos.xyz;
     gl_Position = projection_matrix * pos;
     vary_normal = normalize((mat*vec4(normal.xyz+position.xyz,1.0)).xyz-pos.xyz);
 #else
+    vary_position = (modelview_matrix * vec4(position.xyz, 1.0)).xyz;
 	gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0); 
     vary_normal = normalize(normal_matrix * normal);
 #endif
diff --git a/indra/newview/app_settings/shaders/class1/deferred/fullbrightF.glsl b/indra/newview/app_settings/shaders/class1/deferred/fullbrightF.glsl
index a6fab10791..52dfed06ae 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/fullbrightF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/fullbrightF.glsl
@@ -50,9 +50,11 @@ void calcAtmosphericVars(vec3 inPositionEye, vec3 light_dir, float ambFactor, ou
 vec4 applySkyAndWaterFog(vec3 pos, vec3 additive, vec3 atten, vec4 color);
 #endif
 
+void mirrorClip(vec3 pos);
+
 void main() 
 {
-
+    mirrorClip(vary_position);
 #ifdef IS_ALPHA
     waterClip(vary_position.xyz);
 #endif
diff --git a/indra/newview/app_settings/shaders/class1/deferred/globalF.glsl b/indra/newview/app_settings/shaders/class1/deferred/globalF.glsl
new file mode 100644
index 0000000000..7e3e7d9271
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/deferred/globalF.glsl
@@ -0,0 +1,45 @@
+/** 
+ * @file class1/deferred/globalF.glsl
+ *
+ * $LicenseInfo:firstyear=2024&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2024, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+
+ // Global helper functions included in every fragment shader
+ // DO NOT declare sampler uniforms here as OS X doesn't compile
+ // them out
+
+uniform float mirror_flag;
+uniform vec4 clipPlane;
+uniform float clipSign;
+
+void mirrorClip(vec3 pos)
+{
+    if (mirror_flag > 0)
+    {
+        if ((dot(pos.xyz, clipPlane.xyz) + clipPlane.w) < 0.0)
+        {
+                discard;
+        }
+    }
+}
+
diff --git a/indra/newview/app_settings/shaders/class1/deferred/materialV.glsl b/indra/newview/app_settings/shaders/class1/deferred/materialV.glsl
index 7cdddfe8db..ddf878ae60 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/materialV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/materialV.glsl
@@ -28,25 +28,18 @@
 #define DIFFUSE_ALPHA_MODE_MASK 2
 #define DIFFUSE_ALPHA_MODE_EMISSIVE 3
 
-#ifdef HAS_SKIN
 uniform mat4 modelview_matrix;
 uniform mat4 projection_matrix;
+uniform mat4 modelview_projection_matrix;
+
+#ifdef HAS_SKIN
 mat4 getObjectSkinnedTransform();
 #else
 uniform mat3 normal_matrix;
-uniform mat4 modelview_projection_matrix;
-#endif
-
-#if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_BLEND)
-
-#if !defined(HAS_SKIN)
-uniform mat4 modelview_matrix;
 #endif
 
 out vec3 vary_position;
 
-#endif
-
 uniform mat4 texture_matrix0;
 
 in vec3 position;
@@ -85,9 +78,7 @@ void main()
 
 	vec3 pos = (mat*vec4(position.xyz,1.0)).xyz;
 
-#if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_BLEND)
 	vary_position = pos;
-#endif
 
 	gl_Position = projection_matrix*vec4(pos,1.0);
 
@@ -133,10 +124,8 @@ void main()
 	
 	vertex_color = diffuse_color;
 
-#if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_BLEND)
 #if !defined(HAS_SKIN)
 	vary_position = (modelview_matrix*vec4(position.xyz, 1.0)).xyz;
 #endif
-#endif
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl
index faa273b834..0683236460 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl
@@ -58,10 +58,17 @@ vec2 encode_normal(vec3 n);
 vec3 linear_to_srgb(vec3 c);
 vec3 srgb_to_linear(vec3 c);
 
+uniform vec4 clipPlane;
+uniform float clipSign;
+
+void mirrorClip(vec3 pos);
+
 uniform mat3 normal_matrix;
 
 void main()
 {
+    mirrorClip(vary_position);
+
     vec4 basecolor = texture(diffuseMap, base_color_texcoord.xy).rgba;
     if (basecolor.a < minimum_alpha)
     {
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl
index 160ae7a215..5e0141910b 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl
@@ -28,8 +28,9 @@
 
 //deferred opaque implementation
 
-#ifdef HAS_SKIN
 uniform mat4 modelview_matrix;
+
+#ifdef HAS_SKIN
 uniform mat4 projection_matrix;
 mat4 getObjectSkinnedTransform();
 #else
@@ -59,6 +60,7 @@ out vec4 vertex_color;
 out vec3 vary_tangent;
 flat out float vary_sign;
 out vec3 vary_normal;
+out vec3 vary_position;
 
 vec2 texture_transform(vec2 vertex_texcoord, vec4[2] khr_gltf_transform, mat4 sl_animation_transform);
 vec3 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform, mat4 sl_animation_transform);
@@ -71,10 +73,11 @@ void main()
 	mat = modelview_matrix * mat;
 
 	vec3 pos = (mat*vec4(position.xyz,1.0)).xyz;
-
+    vary_position = pos;
 	gl_Position = projection_matrix*vec4(pos,1.0);
 
 #else
+    vary_position = (modelview_matrix*vec4(position.xyz, 1.0)).xyz;
 	//transform vertex
 	gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0); 
 #endif
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainF.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainF.glsl
new file mode 100644
index 0000000000..c83a6be85d
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainF.glsl
@@ -0,0 +1,344 @@
+/** 
+ * @file class1\deferred\terrainF.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+/*[EXTRA_CODE_HERE]*/
+
+#define TERRAIN_PBR_DETAIL_EMISSIVE 0
+#define TERRAIN_PBR_DETAIL_OCCLUSION -1
+#define TERRAIN_PBR_DETAIL_NORMAL -2
+#define TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS -3
+
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+#define TerrainCoord vec4[2]
+#elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
+#define TerrainCoord vec2
+#endif
+
+#define MIX_X    1 << 3
+#define MIX_Y    1 << 4
+#define MIX_Z    1 << 5
+#define MIX_W    1 << 6
+
+struct TerrainMix
+{
+    vec4 weight;
+    int type;
+};
+
+TerrainMix get_terrain_mix_weights(float alpha1, float alpha2, float alphaFinal);
+
+struct PBRMix
+{
+    vec4 col;       // RGB color with alpha, linear space
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    vec3 orm;       // Occlusion, roughness, metallic
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    vec2 rm;        // Roughness, metallic
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    vec3 vNt;       // Unpacked normal texture sample, vector
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    vec3 emissive;  // RGB emissive color, linear space
+#endif
+};
+
+PBRMix init_pbr_mix();
+
+PBRMix terrain_sample_and_multiply_pbr(
+    TerrainCoord terrain_coord
+    , sampler2D tex_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    , sampler2D tex_orm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    , sampler2D tex_vNt
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    , sampler2D tex_emissive
+#endif
+    , vec4 factor_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    , vec3 factor_orm
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    , vec2 factor_rm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    , vec3 factor_emissive
+#endif
+    );
+
+PBRMix mix_pbr(PBRMix mix1, PBRMix mix2, float mix2_weight);
+
+out vec4 frag_data[4];
+
+uniform sampler2D alpha_ramp;
+
+// https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#additional-textures
+uniform sampler2D detail_0_base_color;
+uniform sampler2D detail_1_base_color;
+uniform sampler2D detail_2_base_color;
+uniform sampler2D detail_3_base_color;
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+uniform sampler2D detail_0_normal;
+uniform sampler2D detail_1_normal;
+uniform sampler2D detail_2_normal;
+uniform sampler2D detail_3_normal;
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+uniform sampler2D detail_0_metallic_roughness;
+uniform sampler2D detail_1_metallic_roughness;
+uniform sampler2D detail_2_metallic_roughness;
+uniform sampler2D detail_3_metallic_roughness;
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+uniform sampler2D detail_0_emissive;
+uniform sampler2D detail_1_emissive;
+uniform sampler2D detail_2_emissive;
+uniform sampler2D detail_3_emissive;
+#endif
+
+uniform vec4[4] baseColorFactors; // See also vertex_color in pbropaqueV.glsl
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+uniform vec4 metallicFactors;
+uniform vec4 roughnessFactors;
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+uniform vec3[4] emissiveColors;
+#endif
+uniform vec4 minimum_alphas; // PBR alphaMode: MASK, See: mAlphaCutoff, setAlphaCutoff()
+
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+in vec4[2] vary_coords;
+#endif
+in vec3 vary_normal;
+in vec3 vary_tangent;
+flat in float vary_sign;
+in vec4 vary_texcoord0;
+in vec4 vary_texcoord1;
+
+vec2 encode_normal(vec3 n);
+
+float terrain_mix(TerrainMix tm, vec4 tms4);
+
+void main()
+{
+
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+    TerrainCoord terrain_texcoord = vary_coords;
+#elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
+    TerrainCoord terrain_texcoord = vary_texcoord0.xy;
+#endif
+
+    float alpha1 = texture(alpha_ramp, vary_texcoord0.zw).a;
+    float alpha2 = texture(alpha_ramp,vary_texcoord1.xy).a;
+    float alphaFinal = texture(alpha_ramp, vary_texcoord1.zw).a;
+
+    TerrainMix tm = get_terrain_mix_weights(alpha1, alpha2, alphaFinal);
+
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    // RGB = Occlusion, Roughness, Metal
+    // default values, see LLViewerTexture::sDefaultPBRORMImagep
+    //   occlusion 1.0
+    //   roughness 0.0
+    //   metal     0.0
+    vec3[4] orm_factors;
+    orm_factors[0] = vec3(1.0, roughnessFactors.x, metallicFactors.x);
+    orm_factors[1] = vec3(1.0, roughnessFactors.y, metallicFactors.y);
+    orm_factors[2] = vec3(1.0, roughnessFactors.z, metallicFactors.z);
+    orm_factors[3] = vec3(1.0, roughnessFactors.w, metallicFactors.w);
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    vec2[4] rm_factors;
+    rm_factors[0] = vec2(roughnessFactors.x, metallicFactors.x);
+    rm_factors[1] = vec2(roughnessFactors.y, metallicFactors.y);
+    rm_factors[2] = vec2(roughnessFactors.z, metallicFactors.z);
+    rm_factors[3] = vec2(roughnessFactors.w, metallicFactors.w);
+#endif
+
+    PBRMix mix = init_pbr_mix();
+    PBRMix mix2;
+    switch (tm.type & MIX_X)
+    {
+    case MIX_X:
+        mix2 = terrain_sample_and_multiply_pbr(
+            terrain_texcoord
+            , detail_0_base_color
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , detail_0_metallic_roughness
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+            , detail_0_normal
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , detail_0_emissive
+#endif
+            , baseColorFactors[0]
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+            , orm_factors[0]
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , rm_factors[0]
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , emissiveColors[0]
+#endif
+        );
+        mix = mix_pbr(mix, mix2, tm.weight.x);
+        break;
+    default:
+        break;
+    }
+    switch (tm.type & MIX_Y)
+    {
+    case MIX_Y:
+        mix2 = terrain_sample_and_multiply_pbr(
+            terrain_texcoord
+            , detail_1_base_color
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , detail_1_metallic_roughness
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+            , detail_1_normal
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , detail_1_emissive
+#endif
+            , baseColorFactors[1]
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+            , orm_factors[1]
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , rm_factors[1]
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , emissiveColors[1]
+#endif
+        );
+        mix = mix_pbr(mix, mix2, tm.weight.y);
+        break;
+    default:
+        break;
+    }
+    switch (tm.type & MIX_Z)
+    {
+    case MIX_Z:
+        mix2 = terrain_sample_and_multiply_pbr(
+            terrain_texcoord
+            , detail_2_base_color
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , detail_2_metallic_roughness
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+            , detail_2_normal
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , detail_2_emissive
+#endif
+            , baseColorFactors[2]
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+            , orm_factors[2]
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , rm_factors[2]
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , emissiveColors[2]
+#endif
+        );
+        mix = mix_pbr(mix, mix2, tm.weight.z);
+        break;
+    default:
+        break;
+    }
+    switch (tm.type & MIX_W)
+    {
+    case MIX_W:
+        mix2 = terrain_sample_and_multiply_pbr(
+            terrain_texcoord
+            , detail_3_base_color
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , detail_3_metallic_roughness
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+            , detail_3_normal
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , detail_3_emissive
+#endif
+            , baseColorFactors[3]
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+            , orm_factors[3]
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , rm_factors[3]
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , emissiveColors[3]
+#endif
+        );
+        mix = mix_pbr(mix, mix2, tm.weight.w);
+        break;
+    default:
+        break;
+    }
+
+    float minimum_alpha = terrain_mix(tm, minimum_alphas);
+    if (mix.col.a < minimum_alpha)
+    {
+        discard;
+    }
+    float base_color_factor_alpha = terrain_mix(tm, vec4(baseColorFactors[0].z, baseColorFactors[1].z, baseColorFactors[2].z, baseColorFactors[3].z));
+
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    // from mikktspace.com
+    vec3 vNt = mix.vNt;
+    vec3 vN = vary_normal;
+    vec3 vT = vary_tangent.xyz;
+    
+    vec3 vB = vary_sign * cross(vN, vT);
+    vec3 tnorm = normalize( vNt.x * vT + vNt.y * vB + vNt.z * vN );
+
+    tnorm *= gl_FrontFacing ? 1.0 : -1.0;
+#else
+    vec3 tnorm = vary_normal;
+    tnorm *= gl_FrontFacing ? 1.0 : -1.0;
+#endif
+   
+
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+#define emissive mix.emissive
+#else
+#define emissive vec3(0)
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+#define orm mix.orm
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+#define orm vec3(1.0, mix.rm)
+#else
+// Matte plastic potato terrain
+#define orm vec3(1.0, 1.0, 0.0)
+#endif
+    frag_data[0] = max(vec4(mix.col.xyz, 0.0), vec4(0));                                                   // Diffuse
+    frag_data[1] = max(vec4(orm.rgb, base_color_factor_alpha), vec4(0));                                    // PBR linear packed Occlusion, Roughness, Metal.
+    frag_data[2] = max(vec4(encode_normal(tnorm), base_color_factor_alpha, GBUFFER_FLAG_HAS_PBR), vec4(0)); // normal, environment intensity, flags
+    frag_data[3] = max(vec4(emissive,0), vec4(0));                                                // PBR sRGB Emissive
+}
+
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainUtilF.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainUtilF.glsl
new file mode 100644
index 0000000000..935c3f9301
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainUtilF.glsl
@@ -0,0 +1,473 @@
+/** 
+ * @file class1\deferred\pbrterrainUtilF.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+/*[EXTRA_CODE_HERE]*/
+
+/**
+ * Triplanar mapping implementation adapted from Inigo Quilez' example shader,
+ * MIT license.
+ * https://www.shadertoy.com/view/MtsGWH
+ * Copyright © 2015 Inigo Quilez
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions: The above copyright
+ * notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS",
+ * WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+ * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+ * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#define TERRAIN_PBR_DETAIL_EMISSIVE 0
+#define TERRAIN_PBR_DETAIL_OCCLUSION -1
+#define TERRAIN_PBR_DETAIL_NORMAL -2
+#define TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS -3
+
+in vec3 vary_vertex_normal;
+
+vec3 srgb_to_linear(vec3 c);
+
+// A relatively agressive threshold for terrain material mixing sampling
+// cutoff. This ensures that only one or two materials are used in most places,
+// making PBR terrain blending more performant. Should be greater than 0 to work.
+#define TERRAIN_RAMP_MIX_THRESHOLD 0.1
+// A small threshold for triplanar mapping sampling cutoff. This and
+// TERRAIN_TRIPLANAR_BLEND_FACTOR together ensures that only one or two samples
+// per texture are used in most places, making triplanar mapping more
+// performant. Should be greater than 0 to work.
+// There's also an artistic design choice in the use of these factors, and the
+// use of triplanar generally. Don't take these triplanar constants for granted.
+#define TERRAIN_TRIPLANAR_MIX_THRESHOLD 0.01
+
+#define SAMPLE_X 1 << 0
+#define SAMPLE_Y 1 << 1
+#define SAMPLE_Z 1 << 2
+#define MIX_X    1 << 3
+#define MIX_Y    1 << 4
+#define MIX_Z    1 << 5
+#define MIX_W    1 << 6
+
+struct PBRMix
+{
+    vec4 col;       // RGB color with alpha, linear space
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    vec3 orm;       // Occlusion, roughness, metallic
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    vec2 rm;        // Roughness, metallic
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    vec3 vNt;       // Unpacked normal texture sample, vector
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    vec3 emissive;  // RGB emissive color, linear space
+#endif
+};
+
+PBRMix init_pbr_mix()
+{
+    PBRMix mix;
+    mix.col = vec4(0);
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    mix.orm = vec3(0);
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    mix.rm = vec2(0);
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    mix.vNt = vec3(0);
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    mix.emissive = vec3(0);
+#endif
+    return mix;
+}
+
+// Usage example, for two weights:
+// vec2 weights = ... // Weights must add up to 1
+// PBRMix mix = init_pbr_mix();
+// PBRMix mix1 = ...
+// mix = mix_pbr(mix, mix1, weights.x);
+// PBRMix mix2 = ...
+// mix = mix_pbr(mix, mix2, weights.y);
+PBRMix mix_pbr(PBRMix mix1, PBRMix mix2, float mix2_weight)
+{
+    PBRMix mix;
+    mix.col      = mix1.col      + (mix2.col      * mix2_weight);
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    mix.orm      = mix1.orm      + (mix2.orm      * mix2_weight);
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    mix.rm       = mix1.rm       + (mix2.rm       * mix2_weight);
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    mix.vNt      = mix1.vNt      + (mix2.vNt      * mix2_weight);
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    mix.emissive = mix1.emissive + (mix2.emissive * mix2_weight);
+#endif
+    return mix;
+}
+
+PBRMix sample_pbr(
+    vec2 uv
+    , sampler2D tex_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    , sampler2D tex_orm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    , sampler2D tex_vNt
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    , sampler2D tex_emissive
+#endif
+    )
+{
+    PBRMix mix;
+    mix.col = texture(tex_col, uv);
+    mix.col.rgb = srgb_to_linear(mix.col.rgb);
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    mix.orm = texture(tex_orm, uv).xyz;
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    mix.rm = texture(tex_orm, uv).yz;
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    mix.vNt = texture(tex_vNt, uv).xyz*2.0-1.0;
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    mix.emissive = srgb_to_linear(texture(tex_emissive, uv).xyz);
+#endif
+    return mix;
+}
+
+struct TerrainTriplanar
+{
+    vec3 weight;
+    int type;
+};
+
+struct TerrainMix
+{
+    vec4 weight;
+    int type;
+};
+
+#define TerrainMixSample vec4[4]
+#define TerrainMixSample3 vec3[4]
+
+TerrainMix get_terrain_mix_weights(float alpha1, float alpha2, float alphaFinal)
+{
+    TerrainMix tm;
+    vec4 sample_x = vec4(1,0,0,0);
+    vec4 sample_y = vec4(0,1,0,0);
+    vec4 sample_z = vec4(0,0,1,0);
+    vec4 sample_w = vec4(0,0,0,1);
+
+    tm.weight = mix( mix(sample_w, sample_z, alpha2), mix(sample_y, sample_x, alpha1), alphaFinal );
+    tm.weight -= TERRAIN_RAMP_MIX_THRESHOLD;
+    ivec4 usage = max(ivec4(0), ivec4(ceil(tm.weight)));
+    // Prevent negative weights and keep weights balanced
+    tm.weight = tm.weight*vec4(usage);
+    tm.weight /= (tm.weight.x + tm.weight.y + tm.weight.z + tm.weight.w);
+
+    tm.type = (usage.x * MIX_X) |
+              (usage.y * MIX_Y) |
+              (usage.z * MIX_Z) |
+              (usage.w * MIX_W);
+    return tm;
+}
+
+TerrainTriplanar _t_triplanar()
+{
+    float sharpness = TERRAIN_TRIPLANAR_BLEND_FACTOR;
+    float threshold = TERRAIN_TRIPLANAR_MIX_THRESHOLD;
+    vec3 weight_signed = pow(abs(vary_vertex_normal), vec3(sharpness));
+    weight_signed /= (weight_signed.x + weight_signed.y + weight_signed.z);
+    weight_signed -= vec3(threshold);
+    TerrainTriplanar tw;
+    // *NOTE: Make sure the threshold doesn't affect the materials
+    tw.weight = max(vec3(0), weight_signed);
+    tw.weight /= (tw.weight.x + tw.weight.y + tw.weight.z);
+    ivec3 usage = ivec3(round(max(vec3(0), sign(weight_signed))));
+    tw.type = ((usage.x) * SAMPLE_X) |
+              ((usage.y) * SAMPLE_Y) |
+              ((usage.z) * SAMPLE_Z);
+    return tw;
+}
+
+// Assume weights add to 1
+float terrain_mix(TerrainMix tm, vec4 tms4)
+{
+    return (tm.weight.x * tms4[0]) +
+           (tm.weight.y * tms4[1]) +
+           (tm.weight.z * tms4[2]) +
+           (tm.weight.w * tms4[3]);
+}
+
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+// Triplanar mapping
+
+// Pre-transformed texture coordinates for each axial uv slice (Packing: xy, yz, (-x)z, unused)
+#define TerrainCoord vec4[2]
+
+vec2 _t_uv(vec2 uv_unflipped, float sign_or_zero)
+{
+    // Handle case where sign is 0
+    float sign = (2.0*sign_or_zero) + 1.0;
+    sign /= abs(sign);
+    // If the vertex normal is negative, flip the texture back
+    // right-side up.
+    vec2 uv = uv_unflipped * vec2(sign, 1);
+    return uv;
+}
+
+vec3 _t_normal_post_1(vec3 vNt0, float sign_or_zero)
+{
+    // Assume normal is unpacked
+    vec3 vNt1 = vNt0;
+    // Get sign
+    float sign = sign_or_zero;
+    // Handle case where sign is 0
+    sign = (2.0*sign) + 1.0;
+    sign /= abs(sign);
+    // If the sign is negative, rotate normal by 180 degrees
+    vNt1.xy = (min(0, sign) * vNt1.xy) + (min(0, -sign) * -vNt1.xy);
+    return vNt1;
+}
+
+// Triplanar-specific normal texture fixes
+vec3 _t_normal_post_x(vec3 vNt0)
+{
+    vec3 vNt_x = _t_normal_post_1(vNt0, sign(vary_vertex_normal.x));
+    // *HACK: Transform normals according to orientation of the UVs
+    vNt_x.xy = vec2(-vNt_x.y, vNt_x.x);
+    return vNt_x;
+}
+vec3 _t_normal_post_y(vec3 vNt0)
+{
+    vec3 vNt_y = _t_normal_post_1(vNt0, sign(vary_vertex_normal.y));
+    // *HACK: Transform normals according to orientation of the UVs
+    vNt_y.xy = -vNt_y.xy;
+    return vNt_y;
+}
+vec3 _t_normal_post_z(vec3 vNt0)
+{
+    vec3 vNt_z = _t_normal_post_1(vNt0, sign(vary_vertex_normal.z));
+    return vNt_z;
+}
+
+PBRMix terrain_sample_pbr(
+    TerrainCoord terrain_coord
+    , TerrainTriplanar tw
+    , sampler2D tex_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    , sampler2D tex_orm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    , sampler2D tex_vNt
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    , sampler2D tex_emissive
+#endif
+    )
+{
+    PBRMix mix = init_pbr_mix();
+
+#define get_uv_x() _t_uv(terrain_coord[0].zw, sign(vary_vertex_normal.x))
+#define get_uv_y() _t_uv(terrain_coord[1].xy, sign(vary_vertex_normal.y))
+#define get_uv_z() _t_uv(terrain_coord[0].xy, sign(vary_vertex_normal.z))
+    switch (tw.type & SAMPLE_X)
+    {
+    case SAMPLE_X:
+        PBRMix mix_x = sample_pbr(
+            get_uv_x()
+            , tex_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , tex_orm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+            , tex_vNt
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , tex_emissive
+#endif
+            );
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+        // Triplanar-specific normal texture fix
+        mix_x.vNt = _t_normal_post_x(mix_x.vNt);
+#endif
+        mix = mix_pbr(mix, mix_x, tw.weight.x);
+        break;
+    default:
+        break;
+    }
+
+    switch (tw.type & SAMPLE_Y)
+    {
+    case SAMPLE_Y:
+        PBRMix mix_y = sample_pbr(
+            get_uv_y()
+            , tex_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , tex_orm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+            , tex_vNt
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , tex_emissive
+#endif
+            );
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+        // Triplanar-specific normal texture fix
+        mix_y.vNt = _t_normal_post_y(mix_y.vNt);
+#endif
+        mix = mix_pbr(mix, mix_y, tw.weight.y);
+        break;
+    default:
+        break;
+    }
+
+    switch (tw.type & SAMPLE_Z)
+    {
+    case SAMPLE_Z:
+        PBRMix mix_z = sample_pbr(
+            get_uv_z()
+            , tex_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+            , tex_orm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+            , tex_vNt
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+            , tex_emissive
+#endif
+            );
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+        // Triplanar-specific normal texture fix
+        // *NOTE: Bottom face has not been tested
+        mix_z.vNt = _t_normal_post_z(mix_z.vNt);
+#endif
+        mix = mix_pbr(mix, mix_z, tw.weight.z);
+        break;
+    default:
+        break;
+    }
+    
+    return mix;
+}
+
+#elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
+
+#define TerrainCoord vec2
+
+#define terrain_sample_pbr sample_pbr
+
+#endif
+
+PBRMix multiply_factors_pbr(
+    PBRMix mix_in
+    , vec4 factor_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    , vec3 factor_orm
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    , vec2 factor_rm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    , vec3 factor_emissive
+#endif
+    )
+{
+    PBRMix mix = mix_in;
+    mix.col *= factor_col;
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    mix.orm *= factor_orm;
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    mix.rm *= factor_rm;
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    mix.emissive *= factor_emissive;
+#endif
+    return mix;
+}
+
+PBRMix terrain_sample_and_multiply_pbr(
+    TerrainCoord terrain_coord
+    , sampler2D tex_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    , sampler2D tex_orm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+    , sampler2D tex_vNt
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    , sampler2D tex_emissive
+#endif
+    , vec4 factor_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+    , vec3 factor_orm
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    , vec2 factor_rm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    , vec3 factor_emissive
+#endif
+    )
+{
+    PBRMix mix = terrain_sample_pbr(
+        terrain_coord
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+        , _t_triplanar()
+#endif
+        , tex_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+        , tex_orm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
+        , tex_vNt
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+        , tex_emissive
+#endif
+        );
+
+    mix = multiply_factors_pbr(mix
+        , factor_col
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+        , factor_orm
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+        , factor_rm
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
+        , factor_emissive
+#endif
+    );
+
+    return mix;
+}
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
new file mode 100644
index 0000000000..dbb9404219
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
@@ -0,0 +1,93 @@
+/** 
+ * @file class1\environment\pbrterrainV.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+uniform mat3 normal_matrix;
+uniform mat4 texture_matrix0;
+uniform mat4 modelview_projection_matrix;
+
+in vec3 position;
+in vec3 normal;
+in vec4 tangent;
+in vec4 diffuse_color;
+in vec2 texcoord1;
+
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+out vec4[2] vary_coords;
+#endif
+out vec3 vary_vertex_normal; // Used by pbrterrainUtilF.glsl
+out vec3 vary_normal;
+out vec3 vary_tangent;
+flat out float vary_sign;
+out vec4 vary_texcoord0;
+out vec4 vary_texcoord1;
+
+// *HACK: tangent_space_transform should use texture_normal_transform, or maybe
+// we shouldn't use tangent_space_transform at all. See the call to
+// tangent_space_transform below.
+uniform vec4[2] texture_base_color_transform;
+
+vec2 texture_transform(vec2 vertex_texcoord, vec4[2] khr_gltf_transform, mat4 sl_animation_transform);
+vec3 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform, mat4 sl_animation_transform);
+
+void main()
+{
+    //transform vertex
+	gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0); 
+
+	vec3 n = normal_matrix * normal;
+    vary_vertex_normal = normal;
+	vec3 t = normal_matrix * tangent.xyz;
+
+    vary_tangent = normalize(t);
+    // *TODO: Decide if we want this. It may be better to just calculate the
+    // tangents on-the-fly in the fragment shader, due to the subtleties of the
+    // effect of triplanar mapping on UVs.
+    // *HACK: Should be using texture_normal_transform here. The KHR texture
+    // transform spec requires handling texture transforms separately for each
+    // individual texture.
+    vary_tangent = normalize(tangent_space_transform(vec4(t, tangent.w), n, texture_base_color_transform, texture_matrix0));
+    vary_sign = tangent.w;
+    vary_normal = normalize(n);
+
+    // Transform and pass tex coords
+    // *HACK: texture_base_color_transform is used for all of these here, but
+    // the KHR texture transform spec requires handling texture transforms
+    // separately for each individual texture.
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+    // xy
+    vary_coords[0].xy = texture_transform(position.xy, texture_base_color_transform, texture_matrix0);
+    // yz
+    vary_coords[0].zw = texture_transform(position.yz, texture_base_color_transform, texture_matrix0);
+    // (-x)z
+    vary_coords[1].xy = texture_transform(position.xz * vec2(-1, 1), texture_base_color_transform, texture_matrix0);
+#elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
+    vary_texcoord0.xy = texture_transform(position.xy, texture_base_color_transform, texture_matrix0);
+#endif
+    
+    vec4 tc = vec4(texcoord1,0,1);
+    vary_texcoord0.zw = tc.xy;
+    vary_texcoord1.xy = tc.xy-vec2(2.0, 0.0);
+    vary_texcoord1.zw = tc.xy-vec2(1.0, 0.0);
+}
diff --git a/indra/newview/app_settings/shaders/class1/deferred/terrainF.glsl b/indra/newview/app_settings/shaders/class1/deferred/terrainF.glsl
index f6d509e2c6..2dba7cb9d9 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/terrainF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/terrainF.glsl
@@ -39,9 +39,11 @@ in vec4 vary_texcoord0;
 in vec4 vary_texcoord1;
 
 vec2 encode_normal(vec3 n);
+void mirrorClip(vec3 position);
 
 void main()
 {
+    mirrorClip(pos);
     /// Note: This should duplicate the blending functionality currently used for the terrain rendering.
     
     vec4 color0 = texture(detail_0, vary_texcoord0.xy);
diff --git a/indra/newview/app_settings/shaders/class1/deferred/terrainV.glsl b/indra/newview/app_settings/shaders/class1/deferred/terrainV.glsl
index f6d3b59e85..8e1e4b54d5 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/terrainV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/terrainV.glsl
@@ -25,12 +25,12 @@
 
 uniform mat3 normal_matrix;
 uniform mat4 texture_matrix0;
+uniform mat4 modelview_matrix;
 uniform mat4 modelview_projection_matrix;
 
 in vec3 position;
 in vec3 normal;
 in vec4 diffuse_color;
-in vec2 texcoord0;
 in vec2 texcoord1;
 
 out vec3 pos;
@@ -41,18 +41,16 @@ out vec4 vary_texcoord1;
 uniform vec4 object_plane_s;
 uniform vec4 object_plane_t;
 
-vec4 texgen_object(vec4  vpos, vec4 tc, mat4 mat, vec4 tp0, vec4 tp1)
+vec2 texgen_object(vec4 vpos, mat4 mat, vec4 tp0, vec4 tp1)
 {
     vec4 tcoord;
     
     tcoord.x = dot(vpos, tp0);
     tcoord.y = dot(vpos, tp1);
-    tcoord.z = tc.z;
-    tcoord.w = tc.w;
     
     tcoord = mat * tcoord; 
     
-    return tcoord; 
+    return tcoord.xy; 
 }
 
 void main()
@@ -62,12 +60,12 @@ void main()
     vec4 t_pos = modelview_projection_matrix * pre_pos;
 
     gl_Position = t_pos;
-    pos = t_pos.xyz;
+    pos = (modelview_matrix*pre_pos).xyz;
 
     vary_normal = normalize(normal_matrix * normal);
     
     // Transform and pass tex coords
-    vary_texcoord0.xy = texgen_object(vec4(position, 1.0), vec4(texcoord0,0,1), texture_matrix0, object_plane_s, object_plane_t).xy;
+    vary_texcoord0.xy = texgen_object(vec4(position, 1.0), texture_matrix0, object_plane_s, object_plane_t);
     
     vec4 t = vec4(texcoord1,0,1);
     
diff --git a/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl b/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
index 636dfed4ba..732333311c 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
@@ -65,7 +65,7 @@ vec2 texture_transform(vec2 vertex_texcoord, vec4[2] khr_gltf_transform, mat4 sl
     // Apply texture animation first to avoid shearing and other artifacts
     texcoord = (sl_animation_transform * vec4(texcoord, 0, 1)).xy;
     // Convert to left-handed coordinate system. The offset of 1 is necessary
-    // for rotations to be applied correctly.
+    // for rotation and scale to be applied correctly.
     texcoord.y = 1.0 - texcoord.y;
     texcoord = khr_texture_transform(texcoord, khr_gltf_transform[0].xy, khr_gltf_transform[0].z, khr_gltf_transform[1].xy);
     // Convert back to right-handed coordinate system
diff --git a/indra/newview/app_settings/shaders/class1/deferred/treeF.glsl b/indra/newview/app_settings/shaders/class1/deferred/treeF.glsl
index e2d87e68fa..f108faf283 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/treeF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/treeF.glsl
@@ -32,13 +32,16 @@ uniform sampler2D diffuseMap;
 in vec4 vertex_color;
 in vec3 vary_normal;
 in vec2 vary_texcoord0;
+in vec3 vary_position;
 
 uniform float minimum_alpha;
 
 vec2 encode_normal(vec3 n);
 
+void mirrorClip(vec3 pos);
 void main() 
 {
+    mirrorClip(vary_position);
 	vec4 col = texture(diffuseMap, vary_texcoord0.xy);
 	if (col.a < minimum_alpha)
 	{
diff --git a/indra/newview/app_settings/shaders/class1/deferred/treeV.glsl b/indra/newview/app_settings/shaders/class1/deferred/treeV.glsl
index ce8a10712c..c84fccd4c6 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/treeV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/treeV.glsl
@@ -24,6 +24,7 @@
  */
 
 uniform mat4 texture_matrix0;
+uniform mat4 modelview_matrix;
 uniform mat4 modelview_projection_matrix;
 uniform mat3 normal_matrix;
 
@@ -34,11 +35,14 @@ in vec2 texcoord0;
 out vec3 vary_normal;
 out vec4 vertex_color;
 out vec2 vary_texcoord0;
+out vec3 vary_position;
 
 void main()
 {
 	//transform vertex
 	gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0); 
+    vary_position = (modelview_matrix*vec4(position.xyz, 1.0)).xyz;
+
 	vary_texcoord0 = (texture_matrix0 * vec4(texcoord0,0,1)).xy;
 	
 	vary_normal = normalize(normal_matrix * normal);
diff --git a/indra/newview/app_settings/shaders/class1/interface/normaldebugF.glsl b/indra/newview/app_settings/shaders/class1/interface/normaldebugF.glsl
new file mode 100644
index 0000000000..388042e7e0
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/interface/normaldebugF.glsl
@@ -0,0 +1,33 @@
+/** 
+ * @file normaldebugF.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+out vec4 frag_color;
+
+in vec4 vertex_color;
+
+void main() 
+{
+	frag_color = max(vertex_color, vec4(0));
+}
diff --git a/indra/newview/app_settings/shaders/class1/interface/normaldebugG.glsl b/indra/newview/app_settings/shaders/class1/interface/normaldebugG.glsl
new file mode 100644
index 0000000000..ea04ce1cae
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/interface/normaldebugG.glsl
@@ -0,0 +1,76 @@
+/** 
+ * @file normaldebugG.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+// *NOTE: Geometry shaders have a reputation for being slow. Consider using
+// compute shaders instead, which have a reputation for being fast. This
+// geometry shader in particular seems to run fine on my machine, but I won't
+// vouch for this in performance-critical areas.
+// -Cosmic,2023-09-28
+
+out vec4 vertex_color;
+
+in vec4 normal_g[];
+#if HAS_ATTRIBUTE_TANGENT == 1
+in vec4 tangent_g[];
+#endif
+
+layout(TRIANGLES) in;
+#if HAS_ATTRIBUTE_TANGENT == 1
+layout(LINE_STRIP, max_vertices = 12) out;
+#else
+layout(LINE_STRIP, max_vertices = 6) out;
+#endif
+
+void triangle_normal_debug(int i)
+{
+    // Normal
+    vec4 normal_color = vec4(1.0, 1.0, 0.0, 1.0);
+    gl_Position = gl_in[i].gl_Position;
+    vertex_color = normal_color;
+    EmitVertex();
+    gl_Position = normal_g[i];
+    vertex_color = normal_color;
+    EmitVertex();
+    EndPrimitive();
+
+#if HAS_ATTRIBUTE_TANGENT == 1
+    // Tangent
+    vec4 tangent_color = vec4(0.0, 1.0, 1.0, 1.0);
+    gl_Position = gl_in[i].gl_Position;
+    vertex_color = tangent_color;
+    EmitVertex();
+    gl_Position = tangent_g[i];
+    vertex_color = tangent_color;
+    EmitVertex();
+    EndPrimitive();
+#endif
+}
+
+void main()
+{
+    triangle_normal_debug(0);
+    triangle_normal_debug(1);
+    triangle_normal_debug(2);
+}
diff --git a/indra/newview/app_settings/shaders/class1/interface/normaldebugV.glsl b/indra/newview/app_settings/shaders/class1/interface/normaldebugV.glsl
new file mode 100644
index 0000000000..d1596b9d2a
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/interface/normaldebugV.glsl
@@ -0,0 +1,74 @@
+/** 
+ * @file normaldebugV.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+in vec3 position;
+in vec3 normal;
+out vec4 normal_g;
+#if HAS_ATTRIBUTE_TANGENT == 1
+in vec4 tangent;
+out vec4 tangent_g;
+#endif
+
+uniform float debug_normal_draw_length;
+
+#ifdef HAS_SKIN
+mat4 getObjectSkinnedTransform();
+#else
+uniform mat3 normal_matrix;
+#endif
+uniform mat4 projection_matrix;
+uniform mat4 modelview_matrix;
+
+// *NOTE: Should use the modelview_projection_matrix here in the non-skinned
+// case for efficiency, but opting for the simplier implementation for now as
+// this is debug code. Also, the skinned version hasn't beeen tested yet.
+// world_pos = mat * vec4(position.xyz, 1.0)
+vec4 get_screen_normal(vec3 position, vec4 world_pos, vec3 normal, mat4 mat)
+{
+    vec4 world_norm = mat * vec4((position + normal), 1.0);
+    world_norm.xyz -= world_pos.xyz;
+    world_norm.xyz = debug_normal_draw_length * normalize(world_norm.xyz);
+    world_norm.xyz += world_pos.xyz;
+    return projection_matrix * world_norm;
+}
+
+void main()
+{
+#ifdef HAS_SKIN
+    mat4 mat = getObjectSkinnedTransform();
+    mat = modelview_matrix * mat;
+#else
+#define mat modelview_matrix
+#endif
+
+    vec4 world_pos = mat * vec4(position.xyz,1.0);
+
+	gl_Position = projection_matrix * world_pos;
+	normal_g = get_screen_normal(position.xyz, world_pos, normal.xyz, mat);
+#if HAS_ATTRIBUTE_TANGENT == 1
+	tangent_g = get_screen_normal(position.xyz, world_pos, tangent.xyz, mat);
+#endif
+}
+
diff --git a/indra/newview/app_settings/shaders/class1/interface/radianceGenF.glsl b/indra/newview/app_settings/shaders/class1/interface/radianceGenF.glsl
index 9ecdf0bf77..c1ed1bfe6e 100644
--- a/indra/newview/app_settings/shaders/class1/interface/radianceGenF.glsl
+++ b/indra/newview/app_settings/shaders/class1/interface/radianceGenF.glsl
@@ -38,6 +38,7 @@ in vec3 vary_dir;
 uniform float mipLevel;
 uniform int u_width; 
 uniform float max_probe_lod;
+uniform float probe_strength;
 
 
 // =============================================================================================================
@@ -129,7 +130,7 @@ vec4 prefilterEnvMap(vec3 R)
 	float totalWeight = 0.0;
 	float envMapDim = float(textureSize(reflectionProbes, 0).s);
     float roughness = mipLevel/max_probe_lod;
-    int numSamples = max(int(32*roughness), 1);
+    int numSamples = max(int(PROBE_FILTER_SAMPLES*roughness), 1);
 
     float numMips = max_probe_lod+1;
 
@@ -163,5 +164,6 @@ void main()
 {		
 	vec3 N = normalize(vary_dir);
 	frag_color = max(prefilterEnvMap(N), vec4(0));
+    frag_color.a *= probe_strength;
 }
 // =============================================================================================================
diff --git a/indra/newview/app_settings/shaders/class1/objects/bumpF.glsl b/indra/newview/app_settings/shaders/class1/objects/bumpF.glsl
index 67c99530e3..142f2a5d71 100644
--- a/indra/newview/app_settings/shaders/class1/objects/bumpF.glsl
+++ b/indra/newview/app_settings/shaders/class1/objects/bumpF.glsl
@@ -30,9 +30,13 @@ uniform sampler2D texture1;
 
 in vec2 vary_texcoord0;
 in vec2 vary_texcoord1;
+in vec3 vary_position;
+
+void mirrorClip(vec3 pos);
 
 void main() 
 {
+    mirrorClip(vary_position);
 	float tex0 = texture(texture0, vary_texcoord0.xy).a;
 	float tex1 = texture(texture1, vary_texcoord1.xy).a;
 
diff --git a/indra/newview/app_settings/shaders/class1/objects/bumpV.glsl b/indra/newview/app_settings/shaders/class1/objects/bumpV.glsl
index 7d5417919e..b8a02fbdec 100644
--- a/indra/newview/app_settings/shaders/class1/objects/bumpV.glsl
+++ b/indra/newview/app_settings/shaders/class1/objects/bumpV.glsl
@@ -23,6 +23,7 @@
  * $/LicenseInfo$
  */
 
+uniform mat4 modelview_matrix;
 uniform mat4 texture_matrix0;
 uniform mat4 modelview_projection_matrix;
 
@@ -32,11 +33,11 @@ in vec2 texcoord1;
 
 out vec2 vary_texcoord0;
 out vec2 vary_texcoord1;
+out vec3 vary_position;
 
 #ifdef HAS_SKIN
 mat4 getObjectSkinnedTransform();
 uniform mat4 projection_matrix;
-uniform mat4 modelview_matrix;
 #endif
 
 void main()
@@ -46,8 +47,10 @@ void main()
     mat4 mat = getObjectSkinnedTransform();
     mat = modelview_matrix * mat;
     vec4 pos = mat * vec4(position.xyz, 1.0);
+    vary_position = pos.xyz;
     gl_Position = projection_matrix * pos;
 #else
+    vary_position = (modelview_matrix * vec4(position.xyz, 1.0)).xyz;
 	gl_Position = modelview_projection_matrix*vec4(position.xyz, 1.0);
 #endif
 	vary_texcoord0 = (texture_matrix0 * vec4(texcoord0,0,1)).xy;
diff --git a/indra/newview/app_settings/shaders/class2/deferred/alphaF.glsl b/indra/newview/app_settings/shaders/class2/deferred/alphaF.glsl
index acd32a81b3..4aef22c296 100644
--- a/indra/newview/app_settings/shaders/class2/deferred/alphaF.glsl
+++ b/indra/newview/app_settings/shaders/class2/deferred/alphaF.glsl
@@ -78,6 +78,8 @@ float sampleDirectionalShadow(vec3 pos, vec3 norm, vec2 pos_screen);
 
 float getAmbientClamp();
 
+void mirrorClip(vec3 pos);
+
 void sampleReflectionProbesLegacy(inout vec3 ambenv, inout vec3 glossenv, inout vec3 legacyenv,
         vec2 tc, vec3 pos, vec3 norm, float glossiness, float envIntensity, bool transparent, vec3 amblit_linear);
 
@@ -167,6 +169,8 @@ vec3 calcPointLightOrSpotLight(vec3 light_col, vec3 diffuse, vec3 v, vec3 n, vec
 
 void main() 
 {
+    mirrorClip(vary_position);
+
     vec2 frag = vary_fragcoord.xy/vary_fragcoord.z*0.5+0.5;
     
     vec4 pos = vec4(vary_position, 1.0);
diff --git a/indra/newview/app_settings/shaders/class2/deferred/pbralphaF.glsl b/indra/newview/app_settings/shaders/class2/deferred/pbralphaF.glsl
index 003dd05e6f..059c2a64ce 100644
--- a/indra/newview/app_settings/shaders/class2/deferred/pbralphaF.glsl
+++ b/indra/newview/app_settings/shaders/class2/deferred/pbralphaF.glsl
@@ -90,6 +90,7 @@ float sampleDirectionalShadow(vec3 pos, vec3 norm, vec2 pos_screen);
 void sampleReflectionProbes(inout vec3 ambenv, inout vec3 glossenv, 
         vec2 tc, vec3 pos, vec3 norm, float glossiness, bool transparent, vec3 amblit_linear);
 
+void mirrorClip(vec3 pos);
 void waterClip(vec3 pos);
 
 void calcDiffuseSpecular(vec3 baseColor, float metallic, inout vec3 diffuseColor, inout vec3 specularColor);
@@ -156,6 +157,8 @@ vec3 calcPointLightOrSpotLight(vec3 diffuseColor, vec3 specularColor,
 
 void main()
 {
+    mirrorClip(vary_position);
+
     vec3 color = vec3(0,0,0);
 
     vec3  light_dir   = (sun_up_factor == 1) ? sun_dir : moon_dir;
diff --git a/indra/newview/app_settings/shaders/class3/deferred/fullbrightShinyF.glsl b/indra/newview/app_settings/shaders/class3/deferred/fullbrightShinyF.glsl
index 8430cca325..c382a9fbc0 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/fullbrightShinyF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/fullbrightShinyF.glsl
@@ -53,8 +53,11 @@ void sampleReflectionProbesLegacy(inout vec3 ambenv, inout vec3 glossenv, inout
 
 void applyLegacyEnv(inout vec3 color, vec3 legacyenv, vec4 spec, vec3 pos, vec3 norm, float envIntensity);
 
+void mirrorClip(vec3 pos);
+
 void main()
 {
+    mirrorClip(vary_position);
 #ifdef HAS_DIFFUSE_LOOKUP
 	vec4 color = diffuseLookup(vary_texcoord0.xy);
 #else
diff --git a/indra/newview/app_settings/shaders/class3/deferred/materialF.glsl b/indra/newview/app_settings/shaders/class3/deferred/materialF.glsl
index ec1e49eeb4..0476b98e10 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/materialF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/materialF.glsl
@@ -45,6 +45,13 @@ void calcHalfVectors(vec3 lv, vec3 n, vec3 v, out vec3 h, out vec3 l, out float
 vec3 srgb_to_linear(vec3 cs);
 vec3 linear_to_srgb(vec3 cs);
 
+uniform mat4 modelview_matrix;
+uniform mat3 normal_matrix;
+
+in vec3 vary_position;
+
+void mirrorClip(vec3 pos);
+
 #if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_BLEND)
 
 out vec4 frag_color;
@@ -66,12 +73,12 @@ uniform vec4 morphFactor;
 uniform vec3 camPosLocal;
 uniform mat3 env_mat;
 
+uniform float is_mirror;
+
 uniform vec3 sun_dir;
 uniform vec3 moon_dir;
 in vec2 vary_fragcoord;
 
-in vec3 vary_position;
-
 uniform mat4 proj_mat;
 uniform mat4 inv_proj;
 uniform vec2 screen_res;
@@ -285,12 +292,12 @@ float getShadow(vec3 pos, vec3 norm)
 
 void main()
 {
+    mirrorClip(vary_position);
     waterClip();
 
     // diffcol == diffuse map combined with vertex color
     vec4 diffcol = texture(diffuseMap, vary_texcoord0.xy);
 	diffcol.rgb *= vertex_color.rgb;
-
     alphaMask(diffcol.a);
 
     // spec == specular map combined with specular color
@@ -407,9 +414,12 @@ void main()
 
 #else // mode is not DIFFUSE_ALPHA_MODE_BLEND, encode to gbuffer 
     // deferred path               // See: C++: addDeferredAttachment(), shader: softenLightF.glsl
+
+    float flag = GBUFFER_FLAG_HAS_ATMOS;
+
     frag_data[0] = vec4(diffcol.rgb, emissive);        // gbuffer is sRGB for legacy materials
     frag_data[1] = vec4(spec.rgb, glossiness);           // XYZ = Specular color. W = Specular exponent.
-    frag_data[2] = vec4(encode_normal(norm), env, GBUFFER_FLAG_HAS_ATMOS);;   // XY = Normal.  Z = Env. intensity. W = 1 skip atmos (mask off fog)
+    frag_data[2] = vec4(encode_normal(norm), env, flag);;   // XY = Normal.  Z = Env. intensity. W = 1 skip atmos (mask off fog)
     frag_data[3] = vec4(0);
 #endif
 }
diff --git a/indra/newview/app_settings/shaders/class3/deferred/reflectionProbeF.glsl b/indra/newview/app_settings/shaders/class3/deferred/reflectionProbeF.glsl
index 906e66ecc8..4f6e01764a 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/reflectionProbeF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/reflectionProbeF.glsl
@@ -31,6 +31,7 @@ float tapScreenSpaceReflection(int totalSamples, vec2 tc, vec3 viewPos, vec3 n,
 
 uniform samplerCubeArray   reflectionProbes;
 uniform samplerCubeArray   irradianceProbes;
+
 uniform sampler2D sceneMap;
 uniform int cube_snapshot;
 uniform float max_probe_lod;
@@ -681,6 +682,35 @@ vec3 sampleProbeAmbient(vec3 pos, vec3 dir, vec3 amblit)
     return col[1]+col[0];
 }
 
+
+#if defined(HERO_PROBES)
+
+uniform vec4 clipPlane;
+uniform samplerCubeArray heroProbes;
+
+void tapHeroProbe(inout vec3 glossenv, vec3 pos, vec3 norm, float glossiness)
+{
+    float clipDist = dot(pos.xyz, clipPlane.xyz) + clipPlane.w;
+    if (clipDist > 0.0 && clipDist < 0.1 && glossiness > 0.8)
+    {
+        vec3 refnormpersp = reflect(pos.xyz, norm.xyz);
+        if (dot(refnormpersp.xyz, clipPlane.xyz) > 0.0)
+        {
+            glossenv = textureLod(heroProbes, vec4(env_mat * refnormpersp, 0), (1.0-glossiness)*10).xyz;
+        }
+    }
+}
+
+#else
+
+void tapHeroProbe(inout vec3 glossenv, vec3 pos, vec3 norm, float glossiness)
+{
+}
+
+#endif
+
+
+
 void doProbeSample(inout vec3 ambenv, inout vec3 glossenv,
         vec2 tc, vec3 pos, vec3 norm, float glossiness, bool transparent, vec3 amblit)
 {
@@ -712,6 +742,8 @@ void doProbeSample(inout vec3 ambenv, inout vec3 glossenv,
         glossenv = mix(glossenv, ssr.rgb, ssr.a);
     }
 #endif
+
+    tapHeroProbe(glossenv, pos, norm, glossiness);
 }
 
 void sampleReflectionProbes(inout vec3 ambenv, inout vec3 glossenv,
@@ -799,6 +831,7 @@ void sampleReflectionProbesLegacy(inout vec3 ambenv, inout vec3 glossenv, inout
     {
         float lod = (1.0-glossiness)*reflection_lods;
         glossenv = sampleProbes(pos, normalize(refnormpersp), lod);
+        
     }
     
     if (envIntensity > 0.0)
@@ -826,6 +859,9 @@ void sampleReflectionProbesLegacy(inout vec3 ambenv, inout vec3 glossenv, inout
     }
 #endif
 
+    tapHeroProbe(glossenv, pos, norm, glossiness);
+    tapHeroProbe(legacyenv, pos, norm, 1.0);
+
     glossenv = clamp(glossenv, vec3(0), vec3(10));
 }
 
diff --git a/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl b/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
index 5e8fe9301a..cc6e16c64f 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
@@ -32,6 +32,16 @@ uniform sampler2D specularRect;
 uniform sampler2D normalMap;
 uniform sampler2D emissiveRect; // PBR linear packed Occlusion, Roughness, Metal. See: pbropaqueF.glsl
 
+uniform samplerCubeArray   heroProbes;
+
+#if defined(HERO_PROBES)
+layout (std140) uniform HeroProbeData
+{
+    vec4 heroPosition[1];
+    int heroProbeCount;
+};
+#endif
+
 const float M_PI = 3.14159265;
 
 #if defined(HAS_SUN_SHADOW) || defined(HAS_SSAO)
@@ -50,6 +60,7 @@ uniform float ssao_irradiance_max;
 #endif
 
 // Inputs
+uniform vec4 clipPlane;
 uniform mat3 env_mat;
 uniform mat3  ssao_effect_mat;
 uniform vec3 sun_dir;
@@ -178,7 +189,7 @@ void main()
         float gloss      = 1.0 - perceptualRoughness;
         
         sampleReflectionProbes(irradiance, radiance, tc, pos.xyz, norm.xyz, gloss, false, amblit_linear);
-        
+
         adjustIrradiance(irradiance, ambocc);
 
         vec3 diffuseColor;
@@ -209,7 +220,7 @@ void main()
         vec3 legacyenv = vec3(0);
 
         sampleReflectionProbesLegacy(irradiance, glossenv, legacyenv, tc, pos.xyz, norm.xyz, spec.a, envIntensity, false, amblit_linear);
-        
+
         adjustIrradiance(irradiance, ambocc);
 
         // apply lambertian IBL only (see pbrIbl)
@@ -244,6 +255,7 @@ void main()
 
             // add radiance map
             applyGlossEnv(color, glossenv, spec, pos.xyz, norm.xyz);
+
         }
 
         color.rgb = mix(color.rgb, baseColor.rgb, baseColor.a);
diff --git a/indra/newview/app_settings/shaders/class3/environment/underWaterF.glsl b/indra/newview/app_settings/shaders/class3/environment/underWaterF.glsl
index 223e55eb69..ef086fc3be 100644
--- a/indra/newview/app_settings/shaders/class3/environment/underWaterF.glsl
+++ b/indra/newview/app_settings/shaders/class3/environment/underWaterF.glsl
@@ -55,9 +55,11 @@ in vec4 view;
 in vec3 vary_position;
 
 vec4 applyWaterFogViewLinearNoClip(vec3 pos, vec4 color);
+void mirrorClip(vec3 position);
 
 void main() 
 {
+	mirrorClip(vary_position);
 	vec4 color;
 
     //get detail normals
diff --git a/indra/newview/app_settings/shaders/class3/environment/waterF.glsl b/indra/newview/app_settings/shaders/class3/environment/waterF.glsl
index b364e454e8..b2a81aa025 100644
--- a/indra/newview/app_settings/shaders/class3/environment/waterF.glsl
+++ b/indra/newview/app_settings/shaders/class3/environment/waterF.glsl
@@ -35,6 +35,8 @@ vec3 scaleSoftClipFragLinear(vec3 l);
 void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 norm, vec3 light_dir, out vec3 sunlit, out vec3 amblit, out vec3 atten, out vec3 additive);
 vec4 applyWaterFogViewLinear(vec3 pos, vec4 color);
 
+void mirrorClip(vec3 pos);
+
 // PBR interface
 vec2 BRDF(float NoV, float roughness);
 
@@ -129,6 +131,7 @@ vec3 getPositionWithNDC(vec3 ndc);
 
 void main() 
 {
+    mirrorClip(vary_position);
     vN = vary_normal;
     vT = vary_tangent;
     vB = cross(vN, vT);
diff --git a/indra/newview/featuretable.txt b/indra/newview/featuretable.txt
index f92d9a2a0e..965391b5cf 100644
--- a/indra/newview/featuretable.txt
+++ b/indra/newview/featuretable.txt
@@ -1,4 +1,4 @@
-version 59
+version 60
 // The version number above should be incremented IF AND ONLY IF some
 // change has been made that is sufficiently important to justify
 // resetting the graphics preferences of all users to the recommended
@@ -48,6 +48,8 @@ RenderReflectionsEnabled    1   1
 RenderReflectionProbeDetail	1	2
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   3
 RenderTreeLODFactor			1	1.0
 RenderVBOEnable				1	1
 RenderVBOMappingDisable		1	1
@@ -94,6 +96,8 @@ RenderReflectionsEnabled    1   1
 RenderReflectionProbeDetail	1	0
 RenderTerrainDetail			1	0
 RenderTerrainLODFactor		1	1
+RenderTerrainPBRDetail      1   -4
+RenderTerrainPBRPlanarSampleCount 1   1
 RenderTreeLODFactor			1	0
 RenderVolumeLODFactor		1	1.125
 RenderDeferredSSAO			1	0
@@ -123,6 +127,8 @@ RenderReflectionsEnabled    1   1
 RenderReflectionProbeDetail	1	0
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	1.0
+RenderTerrainPBRDetail      1   -1
+RenderTerrainPBRPlanarSampleCount 1   1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.125
 RenderDeferredSSAO			1	0
@@ -150,6 +156,8 @@ RenderLocalLightCount		1	512
 RenderTransparentWater      1   0
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.25
 RenderDeferredSSAO			1	0
@@ -179,6 +187,8 @@ RenderLocalLightCount		1	1024
 RenderTransparentWater      1   1
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.375
 RenderDeferredSSAO			1	0
@@ -208,6 +218,8 @@ RenderLocalLightCount		1	2048
 RenderTransparentWater      1   1
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   3
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.5
 RenderDeferredSSAO			1	1
@@ -236,6 +248,8 @@ RenderMaxPartCount			1	4096
 RenderLocalLightCount		1	4096
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   3
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.75
@@ -264,6 +278,8 @@ RenderLocalLightCount		1	8192
 RenderMaxPartCount			1	8192
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   3
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	1.0
 RenderVolumeLODFactor		1	2.0
@@ -321,3 +337,5 @@ RenderFSAASamples           0   0
 RenderReflectionsEnabled    0   0
 RenderReflectionProbeDetail	0	0
 
+list TexUnit16orLess
+RenderTerrainPBRDetail      1   -1
diff --git a/indra/newview/featuretable_mac.txt b/indra/newview/featuretable_mac.txt
index 40aaccc8cb..61cde82512 100644
--- a/indra/newview/featuretable_mac.txt
+++ b/indra/newview/featuretable_mac.txt
@@ -1,4 +1,4 @@
-version 56
+version 57
 // The version number above should be incremented IF AND ONLY IF some
 // change has been made that is sufficiently important to justify
 // resetting the graphics preferences of all users to the recommended
@@ -45,6 +45,8 @@ RenderObjectBump			1	1
 RenderLocalLightCount		1	4096
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   3
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	1.0
 RenderVBOEnable				1	1
@@ -89,6 +91,8 @@ RenderLocalLightCount		1	8
 RenderMaxPartCount			1	0
 RenderTerrainDetail			1	0
 RenderTerrainLODFactor		1	1
+RenderTerrainPBRDetail      1   -4
+RenderTerrainPBRPlanarSampleCount 1   1
 RenderTransparentWater		1	0
 RenderTreeLODFactor			1	0
 RenderVolumeLODFactor		1	1.125
@@ -118,6 +122,8 @@ RenderMaxPartCount			1	2048
 RenderLocalLightCount		1	256
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	1.0
+RenderTerrainPBRDetail      1   -1
+RenderTerrainPBRPlanarSampleCount 1   1
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.125
@@ -147,6 +153,8 @@ RenderMaxPartCount			1	4096
 RenderLocalLightCount		1	512
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   1
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.25
@@ -176,6 +184,8 @@ RenderMaxPartCount			1	4096
 RenderLocalLightCount		1	1024
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   1
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.375
@@ -205,6 +215,8 @@ RenderMaxPartCount			1	4096
 RenderLocalLightCount		1	2048
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   3
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.5
@@ -234,6 +246,8 @@ RenderMaxPartCount			1	4096
 RenderLocalLightCount		1	4096
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   3
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	0.5
 RenderVolumeLODFactor		1	1.75
@@ -262,6 +276,8 @@ RenderLocalLightCount		1	8192
 RenderMaxPartCount			1	8192
 RenderTerrainDetail			1	1
 RenderTerrainLODFactor		1	2.0
+RenderTerrainPBRDetail      1   0
+RenderTerrainPBRPlanarSampleCount 1   3
 RenderTransparentWater		1	1
 RenderTreeLODFactor			1	1.0
 RenderVolumeLODFactor		1	2.0
@@ -308,6 +324,9 @@ RenderShadowDetail			0	0
 list TexUnit8orLess
 RenderDeferredSSAO			0	0
 
+list TexUnit16orLess
+RenderTerrainPBRDetail      1   -1
+
 list AMD
 RenderDeferredSSAO			1	0
 
diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index e6a47f1c64..28dd2a3c9a 100644
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -229,6 +229,7 @@
 #include "pipeline.h"
 #include "llgesturemgr.h"
 #include "llsky.h"
+#include "llvlcomposition.h"
 #include "llvlmanager.h"
 #include "llviewercamera.h"
 #include "lldrawpoolbump.h"
diff --git a/indra/newview/lldrawable.h b/indra/newview/lldrawable.h
index 970e8c8b2a..fc182fc2e2 100644
--- a/indra/newview/lldrawable.h
+++ b/indra/newview/lldrawable.h
@@ -286,6 +286,7 @@ public:
 		ANIMATED_CHILD  = 0x01000000,
 		ACTIVE_CHILD	= 0x02000000,
 		FOR_UNLOAD		= 0x04000000, //should be unload from memory
+        MIRROR          = 0x08000000, // Used as a mirror, needs a hero probe position to be calculated.
 	} EDrawableFlags;
 
 public:
diff --git a/indra/newview/lldrawpool.cpp b/indra/newview/lldrawpool.cpp
index 50210b06c4..556760632a 100644
--- a/indra/newview/lldrawpool.cpp
+++ b/indra/newview/lldrawpool.cpp
@@ -567,14 +567,19 @@ void LLRenderPass::pushRiggedMaskBatches(U32 type, bool texture, bool batch_text
 
 void LLRenderPass::applyModelMatrix(const LLDrawInfo& params)
 {
-	if (params.mModelMatrix != gGLLastMatrix)
+	applyModelMatrix(params.mModelMatrix);
+}
+
+void LLRenderPass::applyModelMatrix(const LLMatrix4* model_matrix)
+{
+	if (model_matrix != gGLLastMatrix)
 	{
-		gGLLastMatrix = params.mModelMatrix;
+		gGLLastMatrix = model_matrix;
 		gGL.matrixMode(LLRender::MM_MODELVIEW);
 		gGL.loadMatrix(gGLModelView);
-		if (params.mModelMatrix)
+		if (model_matrix)
 		{
-			gGL.multMatrix((GLfloat*) params.mModelMatrix->mMatrix);
+			gGL.multMatrix((GLfloat*) model_matrix->mMatrix);
 		}
 		gPipeline.mMatrixOpCount++;
 	}
@@ -746,6 +751,7 @@ void LLRenderPass::pushUntexturedGLTFBatches(U32 type)
     }
 }
 
+// static
 void LLRenderPass::pushGLTFBatch(LLDrawInfo& params)
 {
     auto& mat = params.mGLTFMaterial;
@@ -764,6 +770,7 @@ void LLRenderPass::pushGLTFBatch(LLDrawInfo& params)
     teardown_texture_matrix(params);
 }
 
+// static
 void LLRenderPass::pushUntexturedGLTFBatch(LLDrawInfo& params)
 {
     auto& mat = params.mGLTFMaterial;
@@ -825,6 +832,7 @@ void LLRenderPass::pushUntexturedRiggedGLTFBatches(U32 type)
 }
 
 
+// static
 void LLRenderPass::pushRiggedGLTFBatch(LLDrawInfo& params, LLVOAvatar*& lastAvatar, U64& lastMeshId)
 {
     if (params.mAvatar.notNull() && (lastAvatar != params.mAvatar || lastMeshId != params.mSkinInfo->mHash))
@@ -837,6 +845,7 @@ void LLRenderPass::pushRiggedGLTFBatch(LLDrawInfo& params, LLVOAvatar*& lastAvat
     pushGLTFBatch(params);
 }
 
+// static
 void LLRenderPass::pushUntexturedRiggedGLTFBatch(LLDrawInfo& params, LLVOAvatar*& lastAvatar, U64& lastMeshId)
 {
     if (params.mAvatar.notNull() && (lastAvatar != params.mAvatar || lastMeshId != params.mSkinInfo->mHash))
diff --git a/indra/newview/lldrawpool.h b/indra/newview/lldrawpool.h
index 0925a01439..c69f386c6d 100644
--- a/indra/newview/lldrawpool.h
+++ b/indra/newview/lldrawpool.h
@@ -58,9 +58,9 @@ public:
 		POOL_SIMPLE,
 		POOL_FULLBRIGHT,
 		POOL_BUMP,
-		POOL_TERRAIN,
         POOL_MATERIALS,
         POOL_GLTF_PBR,
+		POOL_TERRAIN,
         POOL_GRASS,
         POOL_GLTF_PBR_ALPHA_MASK,
 		POOL_TREE,
@@ -349,8 +349,8 @@ public:
 	void resetDrawOrders() { }
 
 	static void applyModelMatrix(const LLDrawInfo& params);
-    // Use before a non-GLTF batch if it is interleaved with GLTF batches that share the same shader
-    static void resetGLTFTextureTransform();
+    // For rendering that doesn't use LLDrawInfo for some reason
+	static void applyModelMatrix(const LLMatrix4* model_matrix);
 	void pushBatches(U32 type, bool texture = true, bool batch_textures = false);
     void pushUntexturedBatches(U32 type);
 
@@ -374,10 +374,10 @@ public:
     void pushUntexturedRiggedGLTFBatches(U32 type);
 
     // push a single GLTF draw call
-    void pushGLTFBatch(LLDrawInfo& params);
-    void pushRiggedGLTFBatch(LLDrawInfo& params, LLVOAvatar*& lastAvatar, U64& lastMeshId);
-    void pushUntexturedGLTFBatch(LLDrawInfo& params);
-    void pushUntexturedRiggedGLTFBatch(LLDrawInfo& params, LLVOAvatar*& lastAvatar, U64& lastMeshId);
+    static void pushGLTFBatch(LLDrawInfo& params);
+    static void pushRiggedGLTFBatch(LLDrawInfo& params, LLVOAvatar*& lastAvatar, U64& lastMeshId);
+    static void pushUntexturedGLTFBatch(LLDrawInfo& params);
+    static void pushUntexturedRiggedGLTFBatch(LLDrawInfo& params, LLVOAvatar*& lastAvatar, U64& lastMeshId);
 
 	void pushMaskBatches(U32 type, bool texture = true, bool batch_textures = false);
     void pushRiggedMaskBatches(U32 type, bool texture = true, bool batch_textures = false);
diff --git a/indra/newview/lldrawpoolterrain.cpp b/indra/newview/lldrawpoolterrain.cpp
index 77189dceae..2d198c5b4b 100644
--- a/indra/newview/lldrawpoolterrain.cpp
+++ b/indra/newview/lldrawpoolterrain.cpp
@@ -54,8 +54,9 @@
 const F32 DETAIL_SCALE = 1.f/16.f;
 int DebugDetailMap = 0;
 
-S32 LLDrawPoolTerrain::sDetailMode = 1;
+S32 LLDrawPoolTerrain::sPBRDetailMode = 0;
 F32 LLDrawPoolTerrain::sDetailScale = DETAIL_SCALE;
+F32 LLDrawPoolTerrain::sPBRDetailScale = DETAIL_SCALE;
 static LLGLSLShader* sShader = NULL;
 static LLTrace::BlockTimerStatHandle FTM_SHADOW_TERRAIN("Terrain Shadow");
 
@@ -66,7 +67,8 @@ LLDrawPoolTerrain::LLDrawPoolTerrain(LLViewerTexture *texturep) :
 {
 	// Hack!
 	sDetailScale = 1.f/gSavedSettings.getF32("RenderTerrainScale");
-	sDetailMode = gSavedSettings.getS32("RenderTerrainDetail");
+	sPBRDetailScale = 1.f/gSavedSettings.getF32("RenderTerrainPBRScale");
+	sPBRDetailMode = gSavedSettings.getS32("RenderTerrainPBRDetail");
 	mAlphaRampImagep = LLViewerTextureManager::getFetchedTexture(IMG_ALPHA_GRAD);
 
 	//gGL.getTexUnit(0)->bind(mAlphaRampImagep.get());
@@ -105,13 +107,7 @@ U32 LLDrawPoolTerrain::getVertexDataMask()
 
 void LLDrawPoolTerrain::prerender()
 {
-	sDetailMode = gSavedSettings.getS32("RenderTerrainDetail");
-}
-
-//static
-S32 LLDrawPoolTerrain::getDetailMode()
-{
-	return sDetailMode;
+    sPBRDetailMode = gSavedSettings.getS32("RenderTerrainPBRDetail");
 }
 
 void LLDrawPoolTerrain::boostTerrainDetailTextures()
@@ -121,8 +117,38 @@ void LLDrawPoolTerrain::boostTerrainDetailTextures()
 	LLVLComposition *compp = regionp->getComposition();
 	for (S32 i = 0; i < 4; i++)
 	{
-		compp->mDetailTextures[i]->setBoostLevel(LLGLTexture::BOOST_TERRAIN);
-        compp->mDetailTextures[i]->addTextureStats(1024.f * 1024.f);
+        constexpr LLGLTexture::EBoostLevel level = LLGLTexture::BOOST_TERRAIN;
+        constexpr float stats = 1024.f * 1024.f;
+
+        LLPointer<LLViewerFetchedTexture>& tex = compp->mDetailTextures[i];
+        llassert(tex.notNull());
+		tex->setBoostLevel(level);
+        tex->addTextureStats(stats);
+
+        LLPointer<LLFetchedGLTFMaterial>& fetched_material = compp->mDetailMaterials[i];
+        if (fetched_material)
+        {
+            if (fetched_material->mBaseColorTexture)
+            {
+                fetched_material->mBaseColorTexture->setBoostLevel(level);
+                fetched_material->mBaseColorTexture->addTextureStats(stats);
+            }
+            if (fetched_material->mNormalTexture)
+            {
+                fetched_material->mNormalTexture->setBoostLevel(level);
+                fetched_material->mNormalTexture->addTextureStats(stats);
+            }
+            if (fetched_material->mMetallicRoughnessTexture)
+            {
+                fetched_material->mMetallicRoughnessTexture->setBoostLevel(level);
+                fetched_material->mMetallicRoughnessTexture->addTextureStats(stats);
+            }
+            if (fetched_material->mEmissiveTexture)
+            {
+                fetched_material->mEmissiveTexture->setBoostLevel(level);
+                fetched_material->mEmissiveTexture->addTextureStats(stats);
+            }
+        }
 	}
 }
 
@@ -130,10 +156,6 @@ void LLDrawPoolTerrain::beginDeferredPass(S32 pass)
 {
 	LL_PROFILE_ZONE_SCOPED_CATEGORY_DRAWPOOL; //LL_RECORD_BLOCK_TIME(FTM_RENDER_TERRAIN);
 	LLFacePool::beginRenderPass(pass);
-
-	sShader = &gDeferredTerrainProgram;
-
-	sShader->bind();
 }
 
 void LLDrawPoolTerrain::endDeferredPass(S32 pass)
@@ -204,19 +226,8 @@ void LLDrawPoolTerrain::drawLoop()
 		{
 			LLFace *facep = *iter;
 
-			LLMatrix4* model_matrix = &(facep->getDrawable()->getRegion()->mRenderMatrix);
-
-			if (model_matrix != gGLLastMatrix)
-			{
-				llassert(gGL.getMatrixMode() == LLRender::MM_MODELVIEW);
-				gGLLastMatrix = model_matrix;
-				gGL.loadMatrix(gGLModelView);
-				if (model_matrix)
-				{
-					gGL.multMatrix((GLfloat*) model_matrix->mMatrix);
-				}
-				gPipeline.mMatrixOpCount++;
-			}
+            llassert(gGL.getMatrixMode() == LLRender::MM_MODELVIEW);
+            LLRenderPass::applyModelMatrix(&facep->getDrawable()->getRegion()->mRenderMatrix);
 
 			facep->renderIndexed();
 		}
@@ -225,9 +236,34 @@ void LLDrawPoolTerrain::drawLoop()
 
 void LLDrawPoolTerrain::renderFullShader()
 {
+    const BOOL use_local_materials = gLocalTerrainMaterials.materialsReady(true, false);
+	// Hack! Get the region that this draw pool is rendering from!
+	LLViewerRegion *regionp = mDrawFace[0]->getDrawable()->getVObj()->getRegion();
+	LLVLComposition *compp = regionp->getComposition();
+    const BOOL use_textures = !use_local_materials && (compp->getMaterialType() == LLTerrainMaterials::Type::TEXTURE);
+    
+    if (use_textures)
+    {
+        // Use textures
+        sShader = &gDeferredTerrainProgram;
+        sShader->bind();
+        renderFullShaderTextures();
+    }
+    else
+    {
+        // Use materials
+        sShader = &gDeferredPBRTerrainProgram;
+        sShader->bind();
+        renderFullShaderPBR(use_local_materials);
+    }
+}
+
+void LLDrawPoolTerrain::renderFullShaderTextures()
+{
 	// Hack! Get the region that this draw pool is rendering from!
 	LLViewerRegion *regionp = mDrawFace[0]->getDrawable()->getVObj()->getRegion();
 	LLVLComposition *compp = regionp->getComposition();
+
 	LLViewerTexture *detail_texture0p = compp->mDetailTextures[0];
 	LLViewerTexture *detail_texture1p = compp->mDetailTextures[1];
 	LLViewerTexture *detail_texture2p = compp->mDetailTextures[2];
@@ -322,6 +358,236 @@ void LLDrawPoolTerrain::renderFullShader()
 	gGL.getTexUnit(detail0)->activate();
 }
 
+// *TODO: Investigate use of bindFast for PBR terrain textures
+void LLDrawPoolTerrain::renderFullShaderPBR(BOOL local_materials)
+{
+	// Hack! Get the region that this draw pool is rendering from!
+	LLViewerRegion *regionp = mDrawFace[0]->getDrawable()->getVObj()->getRegion();
+	LLVLComposition *compp = regionp->getComposition();
+	LLPointer<LLFetchedGLTFMaterial> (*fetched_materials)[LLVLComposition::ASSET_COUNT] = &compp->mDetailMaterials;
+
+	constexpr U32 terrain_material_count = LLVLComposition::ASSET_COUNT;
+#ifdef SHOW_ASSERT
+	constexpr U32 shader_material_count = 1 + LLViewerShaderMgr::TERRAIN_DETAIL3_BASE_COLOR - LLViewerShaderMgr::TERRAIN_DETAIL0_BASE_COLOR;
+	llassert(shader_material_count == terrain_material_count);
+#endif
+
+    if (local_materials)
+    {
+        // Override region terrain with the global local override terrain
+		fetched_materials = &gLocalTerrainMaterials.mDetailMaterials;
+    }
+	const LLGLTFMaterial* materials[terrain_material_count];
+	for (U32 i = 0; i < terrain_material_count; ++i)
+	{
+		materials[i] = (*fetched_materials)[i].get();
+		if (!materials[i]) { materials[i] = &LLGLTFMaterial::sDefault; }
+	}
+
+    S32 detail_basecolor[terrain_material_count];
+    S32 detail_normal[terrain_material_count];
+    S32 detail_metalrough[terrain_material_count];
+    S32 detail_emissive[terrain_material_count];
+
+    for (U32 i = 0; i < terrain_material_count; ++i)
+    {
+		LLViewerTexture* detail_basecolor_texturep = nullptr;
+		LLViewerTexture* detail_normal_texturep = nullptr;
+		LLViewerTexture* detail_metalrough_texturep = nullptr;
+		LLViewerTexture* detail_emissive_texturep = nullptr;
+
+		const LLFetchedGLTFMaterial* fetched_material = (*fetched_materials)[i].get();
+		if (fetched_material)
+		{
+			detail_basecolor_texturep = fetched_material->mBaseColorTexture;
+			detail_normal_texturep = fetched_material->mNormalTexture;
+			detail_metalrough_texturep = fetched_material->mMetallicRoughnessTexture;
+			detail_emissive_texturep = fetched_material->mEmissiveTexture;
+		}
+
+        detail_basecolor[i] = sShader->enableTexture(LLViewerShaderMgr::TERRAIN_DETAIL0_BASE_COLOR + i);
+        if (detail_basecolor_texturep)
+        {
+            gGL.getTexUnit(detail_basecolor[i])->bind(detail_basecolor_texturep);
+        }
+        else
+        {
+            gGL.getTexUnit(detail_basecolor[i])->bind(LLViewerFetchedTexture::sWhiteImagep);
+        }
+        gGL.getTexUnit(detail_basecolor[i])->setTextureAddressMode(LLTexUnit::TAM_WRAP);
+        gGL.getTexUnit(detail_basecolor[i])->activate();
+
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_NORMAL)
+        {
+            detail_normal[i] = sShader->enableTexture(LLViewerShaderMgr::TERRAIN_DETAIL0_NORMAL + i);
+            if (detail_normal_texturep)
+            {
+                gGL.getTexUnit(detail_normal[i])->bind(detail_normal_texturep);
+            }
+            else
+            {
+                gGL.getTexUnit(detail_normal[i])->bind(LLViewerFetchedTexture::sFlatNormalImagep);
+            }
+            gGL.getTexUnit(detail_normal[i])->setTextureAddressMode(LLTexUnit::TAM_WRAP);
+            gGL.getTexUnit(detail_normal[i])->activate();
+        }
+
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+        {
+            detail_metalrough[i] = sShader->enableTexture(LLViewerShaderMgr::TERRAIN_DETAIL0_METALLIC_ROUGHNESS + i);
+            if (detail_metalrough_texturep)
+            {
+                gGL.getTexUnit(detail_metalrough[i])->bind(detail_metalrough_texturep);
+            }
+            else
+            {
+                gGL.getTexUnit(detail_metalrough[i])->bind(LLViewerFetchedTexture::sWhiteImagep);
+            }
+            gGL.getTexUnit(detail_metalrough[i])->setTextureAddressMode(LLTexUnit::TAM_WRAP);
+            gGL.getTexUnit(detail_metalrough[i])->activate();
+        }
+
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_EMISSIVE)
+        {
+            detail_emissive[i] = sShader->enableTexture(LLViewerShaderMgr::TERRAIN_DETAIL0_EMISSIVE + i);
+            if (detail_emissive_texturep)
+            {
+                gGL.getTexUnit(detail_emissive[i])->bind(detail_emissive_texturep);
+            }
+            else
+            {
+                gGL.getTexUnit(detail_emissive[i])->bind(LLViewerFetchedTexture::sWhiteImagep);
+            }
+            gGL.getTexUnit(detail_emissive[i])->setTextureAddressMode(LLTexUnit::TAM_WRAP);
+            gGL.getTexUnit(detail_emissive[i])->activate();
+        }
+    }
+
+	LLGLSLShader* shader = LLGLSLShader::sCurBoundShaderPtr;
+	llassert(shader);
+		
+
+    // *TODO: Figure out why this offset is *sometimes* producing seams at the
+    // region edge, and repeat jumps when crossing regions, when
+    // RenderTerrainPBRScale is not a factor of the region scale.
+	LLVector3d region_origin_global = gAgent.getRegion()->getOriginGlobal();
+	F32 offset_x = (F32)fmod(region_origin_global.mdV[VX], 1.0/(F64)sPBRDetailScale)*sPBRDetailScale;
+	F32 offset_y = (F32)fmod(region_origin_global.mdV[VY], 1.0/(F64)sPBRDetailScale)*sPBRDetailScale;
+
+    LLGLTFMaterial::TextureTransform base_color_transform;
+    base_color_transform.mScale = LLVector2(sPBRDetailScale, sPBRDetailScale);
+    base_color_transform.mOffset = LLVector2(offset_x, offset_y);
+    F32 base_color_packed[8];
+    base_color_transform.getPacked(base_color_packed);
+    // *HACK: Use the same texture repeats for all PBR terrain textures for now
+    // (not compliant with KHR texture transform spec)
+    shader->uniform4fv(LLShaderMgr::TEXTURE_BASE_COLOR_TRANSFORM, 2, (F32*)base_color_packed);
+
+    LLSettingsWater::ptr_t pwater = LLEnvironment::instance().getCurrentWater();
+
+	//
+	// Alpha Ramp 
+	//
+	S32 alpha_ramp = sShader->enableTexture(LLViewerShaderMgr::TERRAIN_ALPHARAMP);
+	gGL.getTexUnit(alpha_ramp)->bind(m2DAlphaRampImagep);
+    gGL.getTexUnit(alpha_ramp)->setTextureAddressMode(LLTexUnit::TAM_CLAMP);
+
+    //
+    // GLTF uniforms
+    //
+
+    LLColor4 base_color_factors[terrain_material_count];
+    F32 metallic_factors[terrain_material_count];
+    F32 roughness_factors[terrain_material_count];
+    LLColor3 emissive_colors[terrain_material_count];
+    F32 minimum_alphas[terrain_material_count];
+    for (U32 i = 0; i < terrain_material_count; ++i)
+    {
+        const LLGLTFMaterial* material = materials[i];
+
+        base_color_factors[i] = material->mBaseColor;
+        metallic_factors[i] = material->mMetallicFactor;
+        roughness_factors[i] = material->mRoughnessFactor;
+        emissive_colors[i] = material->mEmissiveColor;
+        // glTF 2.0 Specification 3.9.4. Alpha Coverage
+        // mAlphaCutoff is only valid for LLGLTFMaterial::ALPHA_MODE_MASK
+        // Use 0 here due to GLTF terrain blending (LLGLTFMaterial::bind uses
+        // -1 for easier debugging)
+        F32 min_alpha = -0.0f;
+        if (material->mAlphaMode == LLGLTFMaterial::ALPHA_MODE_MASK)
+        {
+            // dividing the alpha cutoff by transparency here allows the shader to compare against
+            // the alpha value of the texture without needing the transparency value
+            min_alpha = material->mAlphaCutoff/material->mBaseColor.mV[3];
+        }
+        minimum_alphas[i] = min_alpha;
+    }
+    shader->uniform4fv(LLShaderMgr::TERRAIN_BASE_COLOR_FACTORS, terrain_material_count, (F32*)base_color_factors);
+    if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+    {
+        shader->uniform4f(LLShaderMgr::TERRAIN_METALLIC_FACTORS, metallic_factors[0], metallic_factors[1], metallic_factors[2], metallic_factors[3]);
+        shader->uniform4f(LLShaderMgr::TERRAIN_ROUGHNESS_FACTORS, roughness_factors[0], roughness_factors[1], roughness_factors[2], roughness_factors[3]);
+    }
+    if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_EMISSIVE)
+    {
+        shader->uniform3fv(LLShaderMgr::TERRAIN_EMISSIVE_COLORS, terrain_material_count, (F32*)emissive_colors);
+    }
+    shader->uniform4f(LLShaderMgr::TERRAIN_MINIMUM_ALPHAS, minimum_alphas[0], minimum_alphas[1], minimum_alphas[2], minimum_alphas[3]);
+
+	// GL_BLEND disabled by default
+	drawLoop();
+
+	// Disable multitexture
+
+	sShader->disableTexture(LLViewerShaderMgr::TERRAIN_ALPHARAMP);
+
+	gGL.getTexUnit(alpha_ramp)->unbind(LLTexUnit::TT_TEXTURE);
+	gGL.getTexUnit(alpha_ramp)->disable();
+	gGL.getTexUnit(alpha_ramp)->activate();
+
+    for (U32 i = 0; i < terrain_material_count; ++i)
+    {
+        sShader->disableTexture(LLViewerShaderMgr::TERRAIN_DETAIL0_BASE_COLOR + i);
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_NORMAL)
+        {
+            sShader->disableTexture(LLViewerShaderMgr::TERRAIN_DETAIL0_NORMAL + i);
+        }
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+        {
+            sShader->disableTexture(LLViewerShaderMgr::TERRAIN_DETAIL0_METALLIC_ROUGHNESS + i);
+        }
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_EMISSIVE)
+        {
+            sShader->disableTexture(LLViewerShaderMgr::TERRAIN_DETAIL0_EMISSIVE + i);
+        }
+
+        gGL.getTexUnit(detail_basecolor[i])->unbind(LLTexUnit::TT_TEXTURE);
+        gGL.getTexUnit(detail_basecolor[i])->disable();
+        gGL.getTexUnit(detail_basecolor[i])->activate();
+
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_NORMAL)
+        {
+            gGL.getTexUnit(detail_normal[i])->unbind(LLTexUnit::TT_TEXTURE);
+            gGL.getTexUnit(detail_normal[i])->disable();
+            gGL.getTexUnit(detail_normal[i])->activate();
+        }
+
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+        {
+            gGL.getTexUnit(detail_metalrough[i])->unbind(LLTexUnit::TT_TEXTURE);
+            gGL.getTexUnit(detail_metalrough[i])->disable();
+            gGL.getTexUnit(detail_metalrough[i])->activate();
+        }
+
+        if (sPBRDetailMode >= TERRAIN_PBR_DETAIL_EMISSIVE)
+        {
+            gGL.getTexUnit(detail_emissive[i])->unbind(LLTexUnit::TT_TEXTURE);
+            gGL.getTexUnit(detail_emissive[i])->disable();
+            gGL.getTexUnit(detail_emissive[i])->activate();
+        }
+    }
+}
+
 void LLDrawPoolTerrain::hilightParcelOwners()
 {
 	{ //use fullbright shader for highlighting
diff --git a/indra/newview/lldrawpoolterrain.h b/indra/newview/lldrawpoolterrain.h
index 03bef31541..13f031c8e7 100644
--- a/indra/newview/lldrawpoolterrain.h
+++ b/indra/newview/lldrawpoolterrain.h
@@ -37,13 +37,12 @@ public:
     {
         VERTEX_DATA_MASK = LLVertexBuffer::MAP_VERTEX |
                     LLVertexBuffer::MAP_NORMAL |
+                    LLVertexBuffer::MAP_TANGENT | // Only PBR terrain uses this currently
                     LLVertexBuffer::MAP_TEXCOORD0 |
                     LLVertexBuffer::MAP_TEXCOORD1
 	};
 
 	virtual U32 getVertexDataMask();
-	static S32 getDetailMode();
-
 	LLDrawPoolTerrain(LLViewerTexture *texturep);
 	virtual ~LLDrawPoolTerrain();
 
@@ -67,8 +66,9 @@ public:
 	LLPointer<LLViewerTexture> m2DAlphaRampImagep;
 	LLPointer<LLViewerTexture> mAlphaNoiseImagep;
 
-	static S32 sDetailMode;
-	static F32 sDetailScale; // meters per texture
+	static S32 sPBRDetailMode;
+	static F32 sDetailScale; // textures per meter
+	static F32 sPBRDetailScale; // textures per meter
 
 protected:
     void boostTerrainDetailTextures();
@@ -79,6 +79,8 @@ protected:
 	void renderFull2TU();
 	void renderFull4TU();
 	void renderFullShader();
+	void renderFullShaderTextures();
+	void renderFullShaderPBR(BOOL local_materials = false);
 	void drawLoop();
 
 private:
diff --git a/indra/newview/lldrawpooltree.cpp b/indra/newview/lldrawpooltree.cpp
index 9dcbc48697..50c4a2c1b3 100644
--- a/indra/newview/lldrawpooltree.cpp
+++ b/indra/newview/lldrawpooltree.cpp
@@ -85,17 +85,8 @@ void LLDrawPoolTree::renderDeferred(S32 pass)
         {
             LLMatrix4* model_matrix = &(face->getDrawable()->getRegion()->mRenderMatrix);
 
-            if (model_matrix != gGLLastMatrix)
-            {
-                gGLLastMatrix = model_matrix;
-                gGL.loadMatrix(gGLModelView);
-                if (model_matrix)
-                {
-                    llassert(gGL.getMatrixMode() == LLRender::MM_MODELVIEW);
-                    gGL.multMatrix((GLfloat*)model_matrix->mMatrix);
-                }
-                gPipeline.mMatrixOpCount++;
-            }
+            llassert(gGL.getMatrixMode() == LLRender::MM_MODELVIEW);
+            LLRenderPass::applyModelMatrix(model_matrix);
 
             buff->setBuffer();
             buff->drawRange(LLRender::TRIANGLES, 0, buff->getNumVerts() - 1, buff->getNumIndices(), 0);
diff --git a/indra/newview/lldynamictexture.cpp b/indra/newview/lldynamictexture.cpp
index 425acd3392..a66c3876fc 100644
--- a/indra/newview/lldynamictexture.cpp
+++ b/indra/newview/lldynamictexture.cpp
@@ -181,19 +181,26 @@ void LLViewerDynamicTexture::postRender(BOOL success)
 //-----------------------------------------------------------------------------
 BOOL LLViewerDynamicTexture::updateAllInstances()
 {
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_UI;
+
 	sNumRenders = 0;
 	if (gGLManager.mIsDisabled)
 	{
 		return TRUE;
 	}
 
-	bool use_fbo = gPipeline.mBake.isComplete() && !gGLManager.mIsAMD;
+    LLRenderTarget& bake_target = gPipeline.mAuxillaryRT.deferredScreen;
 
-	if (use_fbo)
-	{
-		gPipeline.mBake.bindTarget();
-        gPipeline.mBake.clear();
-	}
+	if (!bake_target.isComplete())
+    {
+        llassert(false);
+		return FALSE;
+    }
+    llassert(bake_target.getWidth() >= LLPipeline::MAX_BAKE_WIDTH);
+    llassert(bake_target.getHeight() >= LLPipeline::MAX_BAKE_WIDTH);
+
+    bake_target.bindTarget();
+    bake_target.clear();
 
 	LLGLSLShader::unbind();
 	LLVertexBuffer::unbind();
@@ -208,11 +215,14 @@ BOOL LLViewerDynamicTexture::updateAllInstances()
 			LLViewerDynamicTexture *dynamicTexture = *iter;
 			if (dynamicTexture->needsRender())
 			{				
+                llassert(dynamicTexture->getFullWidth() <= LLPipeline::MAX_BAKE_WIDTH);
+                llassert(dynamicTexture->getFullHeight() <= LLPipeline::MAX_BAKE_WIDTH);
+
 				glClear(GL_DEPTH_BUFFER_BIT);
 				gDepthDirty = TRUE;
 								
 				gGL.color4f(1,1,1,1);
-                dynamicTexture->setBoundTarget(use_fbo ? &gPipeline.mBake : nullptr);
+                dynamicTexture->setBoundTarget(&bake_target);
 				dynamicTexture->preRender();	// Must be called outside of startRender()
 				result = FALSE;
 				if (dynamicTexture->render())
@@ -229,10 +239,7 @@ BOOL LLViewerDynamicTexture::updateAllInstances()
 		}
 	}
 
-	if (use_fbo)
-	{
-		gPipeline.mBake.flush();
-	}
+	bake_target.flush();
 
     gGL.flush();
 
diff --git a/indra/newview/llenvironment.cpp b/indra/newview/llenvironment.cpp
index 60c2682078..affea3f69c 100644
--- a/indra/newview/llenvironment.cpp
+++ b/indra/newview/llenvironment.cpp
@@ -1675,8 +1675,6 @@ void LLEnvironment::update(const LLViewerCamera * cam)
 
     updateSettingsUniforms();
 
-    // *TODO: potential optimization - this block may only need to be
-    // executed some of the time.  For example for water shaders only.
     {
         LLViewerShaderMgr::shader_iter shaders_iter, end_shaders;
         end_shaders = LLViewerShaderMgr::instance()->endShaders();
@@ -1687,6 +1685,10 @@ void LLEnvironment::update(const LLViewerCamera * cam)
                 || shaders_iter->mShaderGroup == LLGLSLShader::SG_WATER))
             {
                 shaders_iter->mUniformsDirty = TRUE;
+                if (shaders_iter->mRiggedVariant)
+                {
+                    shaders_iter->mRiggedVariant->mUniformsDirty = TRUE;
+                }
             }
         }
     }
diff --git a/indra/newview/llface.cpp b/indra/newview/llface.cpp
index c1776705f9..69e43bb458 100644
--- a/indra/newview/llface.cpp
+++ b/indra/newview/llface.cpp
@@ -1889,7 +1889,7 @@ BOOL LLFace::getGeometryVolume(const LLVolume& volume,
 			F32* normals = (F32*) norm.get();
 			LLVector4a* src = vf.mNormals;
 			LLVector4a* end = src+num_vertices;
-			
+
 			while (src < end)
 			{	
 				LLVector4a normal;
diff --git a/indra/newview/llfeaturemanager.cpp b/indra/newview/llfeaturemanager.cpp
index f482d5a37d..9fff505c2a 100644
--- a/indra/newview/llfeaturemanager.cpp
+++ b/indra/newview/llfeaturemanager.cpp
@@ -664,6 +664,10 @@ void LLFeatureManager::applyBaseMasks()
 	{
 		maskFeatures("TexUnit8orLess");
 	}
+	if (gGLManager.mNumTextureImageUnits <= 16)
+	{
+		maskFeatures("TexUnit16orLess");
+	}
 	if (gGLManager.mVRAM > 512)
 	{
 		maskFeatures("VRAMGT512");
diff --git a/indra/newview/llfetchedgltfmaterial.cpp b/indra/newview/llfetchedgltfmaterial.cpp
index 46b9dffae9..97b959e5cb 100644
--- a/indra/newview/llfetchedgltfmaterial.cpp
+++ b/indra/newview/llfetchedgltfmaterial.cpp
@@ -37,8 +37,6 @@
 LLFetchedGLTFMaterial::LLFetchedGLTFMaterial()
     : LLGLTFMaterial()
     , mExpectedFlusTime(0.f)
-    , mActive(true)
-    , mFetching(false)
 {
 
 }
@@ -242,10 +240,11 @@ void LLFetchedGLTFMaterial::onMaterialComplete(std::function<void()> material_co
     materialCompleteCallbacks.push_back(material_complete);
 }
 
-void LLFetchedGLTFMaterial::materialComplete()
+void LLFetchedGLTFMaterial::materialComplete(bool success)
 {
     llassert(mFetching);
     mFetching = false;
+    mFetchSuccess = success;
 
     for (std::function<void()> material_complete : materialCompleteCallbacks)
     {
@@ -254,55 +253,3 @@ void LLFetchedGLTFMaterial::materialComplete()
     materialCompleteCallbacks.clear();
     materialCompleteCallbacks.shrink_to_fit();
 }
-
-LLPointer<LLViewerFetchedTexture> LLFetchedGLTFMaterial::getUITexture()
-{
-    if (mFetching)
-    {
-        return nullptr;
-    }
-
-    auto fetch_texture_for_ui = [](LLPointer<LLViewerFetchedTexture>& img, const LLUUID& id)
-    {
-        if (id.notNull())
-        {
-            if (LLAvatarAppearanceDefines::LLAvatarAppearanceDictionary::isBakedImageId(id))
-            {
-                LLViewerObject* obj = LLSelectMgr::getInstance()->getSelection()->getFirstObject();
-                if (obj)
-                {
-                    LLViewerTexture* viewerTexture = obj->getBakedTextureForMagicId(id);
-                    img = viewerTexture ? dynamic_cast<LLViewerFetchedTexture*>(viewerTexture) : NULL;
-                }
-
-            }
-            else
-            {
-                img = LLViewerTextureManager::getFetchedTexture(id, FTT_DEFAULT, TRUE, LLGLTexture::BOOST_NONE, LLViewerTexture::LOD_TEXTURE);
-            }
-        }
-        if (img)
-        {
-            img->setBoostLevel(LLGLTexture::BOOST_PREVIEW);
-            img->forceToSaveRawImage(0);
-        }
-    };
-
-    fetch_texture_for_ui(mBaseColorTexture, mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_BASE_COLOR]);
-    fetch_texture_for_ui(mNormalTexture, mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_NORMAL]);
-    fetch_texture_for_ui(mMetallicRoughnessTexture, mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_METALLIC_ROUGHNESS]);
-    fetch_texture_for_ui(mEmissiveTexture, mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_EMISSIVE]);
-
-    if ((mBaseColorTexture && (mBaseColorTexture->getRawImageLevel() != 0)) ||
-        (mNormalTexture && (mNormalTexture->getRawImageLevel() != 0)) ||
-        (mMetallicRoughnessTexture && (mMetallicRoughnessTexture->getRawImageLevel() != 0)) ||
-        (mEmissiveTexture && (mEmissiveTexture->getRawImageLevel() != 0)))
-    {
-        return nullptr;
-    }
-
-    // *HACK: Use one of the PBR texture components as the preview texture for now
-    mPreviewTexture = mBaseColorTexture;
-
-    return mPreviewTexture;
-}
diff --git a/indra/newview/llfetchedgltfmaterial.h b/indra/newview/llfetchedgltfmaterial.h
index a9e539633d..42c835a416 100644
--- a/indra/newview/llfetchedgltfmaterial.h
+++ b/indra/newview/llfetchedgltfmaterial.h
@@ -40,6 +40,8 @@ public:
     virtual ~LLFetchedGLTFMaterial();
 
     LLFetchedGLTFMaterial& operator=(const LLFetchedGLTFMaterial& rhs);
+    // LLGLTFMaterial::operator== is defined, but LLFetchedGLTFMaterial::operator== is not.
+    bool operator==(const LLGLTFMaterial& rhs) const = delete;
 
     // If this material is loaded, fire the given function
     void onMaterialComplete(std::function<void()> material_complete);
@@ -49,8 +51,7 @@ public:
     void bind(LLViewerTexture* media_tex = nullptr);
 
     bool isFetching() const { return mFetching; }
-
-    LLPointer<LLViewerFetchedTexture> getUITexture();
+    bool isLoaded() const { return !mFetching && mFetchSuccess; }
 
     void addTextureEntry(LLTextureEntry* te) override;
     void removeTextureEntry(LLTextureEntry* te) override;
@@ -65,18 +66,16 @@ public:
 
     std::set<LLTextureEntry*> mTextureEntires;
 
-    // Texture used for previewing the material in the UI
-    LLPointer<LLViewerFetchedTexture> mPreviewTexture;
-
 protected:
     // Lifetime management
     
     void materialBegin();
-    void materialComplete();
+    void materialComplete(bool success);
 
     F64 mExpectedFlusTime; // since epoch in seconds
-    bool mActive;
-    bool mFetching;
+    bool mActive = true;
+    bool mFetching = false;
+    bool mFetchSuccess = false;
     std::vector<std::function<void()>> materialCompleteCallbacks;
 };
 
diff --git a/indra/newview/llfloaterregioninfo.cpp b/indra/newview/llfloaterregioninfo.cpp
index d4eb40ff92..2c743d596e 100644
--- a/indra/newview/llfloaterregioninfo.cpp
+++ b/indra/newview/llfloaterregioninfo.cpp
@@ -605,6 +605,26 @@ LLPanelRegionEnvironment* LLFloaterRegionInfo::getPanelEnvironment()
 	return panel;
 }
 
+enum class TerrainMaterialType
+{
+    TEXTURE,
+    PBR_MATERIAL,
+    COUNT
+};
+
+TerrainMaterialType material_type_from_index(S32 index)
+{
+    if (index == 0)
+    {
+        return TerrainMaterialType::TEXTURE;
+    }
+    if (index == 1)
+    {
+        return TerrainMaterialType::PBR_MATERIAL;
+    }
+    return TerrainMaterialType::COUNT;
+}
+
 // static
 LLPanelRegionTerrainInfo* LLFloaterRegionInfo::getPanelRegionTerrain()
 {
@@ -1307,6 +1327,17 @@ void LLPanelRegionDebugInfo::onClickDebugConsole(void* data)
 
 BOOL LLPanelRegionTerrainInfo::validateTextureSizes()
 {
+    // *TODO: Don't early-exit in PBR material terrain editing mode, and
+    // instead do some reasonable checks that the PBR material is compatible
+    // with the terrain rendering pipeline. Err on the side of permissive.
+    LLComboBox* material_type_ctrl = getChild<LLComboBox>("terrain_material_type");
+    if (material_type_ctrl)
+    {
+        const TerrainMaterialType material_type = material_type_from_index(material_type_ctrl->getCurrentIndex());
+        const bool is_material_selected = material_type == TerrainMaterialType::PBR_MATERIAL;
+        if (is_material_selected) { return TRUE; }
+    }
+
     static const S32 MAX_TERRAIN_TEXTURE_SIZE = 1024;
 	for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
 	{
@@ -1324,7 +1355,7 @@ BOOL LLPanelRegionTerrainInfo::validateTextureSizes()
 
 		//LL_INFOS() << "texture detail " << i << " is " << width << "x" << height << "x" << components << LL_ENDL;
 
-		if (components != 3)
+		if (components != 3 && components != 4)
 		{
 			LLSD args;
 			args["TEXTURE_NUM"] = i+1;
@@ -1380,12 +1411,20 @@ BOOL LLPanelRegionTerrainInfo::postBuild()
 	initCtrl("terrain_raise_spin");
 	initCtrl("terrain_lower_spin");
 
+    getChild<LLUICtrl>("terrain_material_type")->setCommitCallback(boost::bind(&LLPanelRegionTerrainInfo::onSelectMaterialType, this));
+
 	std::string buffer;
+
 	for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
 	{
 		buffer = llformat("texture_detail_%d", i);
 		initCtrl(buffer);
 	}
+	for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
+	{
+		buffer = llformat("material_detail_%d", i);
+		initCtrl(buffer);
+	}
 
 	for(S32 i = 0; i < CORNER_COUNT; ++i)
 	{
@@ -1402,10 +1441,78 @@ BOOL LLPanelRegionTerrainInfo::postBuild()
 	mAskedTextureHeights = false;
 	mConfirmedTextureHeights = false;
 
+    refresh();
+
 	return LLPanelRegionInfo::postBuild();
 }
 
 // virtual
+void LLPanelRegionTerrainInfo::refresh()
+{
+    // For simplicity, require restart
+    static BOOL feature_pbr_terrain_enabled = gSavedSettings.getBOOL("RenderTerrainPBREnabled");
+
+    LLTextBox* texture_text = getChild<LLTextBox>("detail_texture_text");
+    if (texture_text) { texture_text->setVisible(!feature_pbr_terrain_enabled); }
+
+    LLComboBox* material_type_ctrl = getChild<LLComboBox>("terrain_material_type");
+    if (material_type_ctrl)
+    {
+        material_type_ctrl->setVisible(feature_pbr_terrain_enabled);
+
+        bool has_material_assets = false;
+
+        std::string buffer;
+        for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
+        {
+            buffer = llformat("material_detail_%d", i);
+            LLTextureCtrl* material_ctrl = getChild<LLTextureCtrl>(buffer);
+            if (material_ctrl && material_ctrl->getImageAssetID().notNull())
+            {
+                has_material_assets = true;
+                break;
+            }
+        }
+
+        TerrainMaterialType material_type = material_type_from_index(material_type_ctrl->getCurrentIndex());
+
+        if (!feature_pbr_terrain_enabled) { material_type = TerrainMaterialType::TEXTURE; }
+
+        const bool is_material_selected = material_type == TerrainMaterialType::PBR_MATERIAL;
+        material_type_ctrl->setEnabled(feature_pbr_terrain_enabled && !(is_material_selected && has_material_assets));
+    }
+}
+
+void LLPanelRegionTerrainInfo::onSelectMaterialType()
+{
+    LLComboBox* material_type_ctrl = getChild<LLComboBox>("terrain_material_type");
+    if (!material_type_ctrl) { return; }
+    const TerrainMaterialType material_type = material_type_from_index(material_type_ctrl->getCurrentIndex());
+    const bool show_texture_controls = material_type == TerrainMaterialType::TEXTURE;
+    const bool show_material_controls = material_type == TerrainMaterialType::PBR_MATERIAL;
+    std::string buffer;
+    LLTextureCtrl* texture_ctrl;
+    for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
+    {
+        buffer = llformat("texture_detail_%d", i);
+        texture_ctrl = getChild<LLTextureCtrl>(buffer);
+        if (texture_ctrl)
+        {
+            texture_ctrl->setVisible(show_texture_controls);
+        }
+    }
+    for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
+    {
+        buffer = llformat("material_detail_%d", i);
+        texture_ctrl = getChild<LLTextureCtrl>(buffer);
+        if (texture_ctrl)
+        {
+            texture_ctrl->setVisible(show_material_controls);
+        }
+    }
+}
+
+// virtual
 bool LLPanelRegionTerrainInfo::refreshFromRegion(LLViewerRegion* region)
 {
 	BOOL owner_or_god = gAgent.isGodlike() 
@@ -1421,18 +1528,30 @@ bool LLPanelRegionTerrainInfo::refreshFromRegion(LLViewerRegion* region)
 		getChild<LLUICtrl>("region_text")->setValue(LLSD(region->getName()));
 
 		LLVLComposition* compp = region->getComposition();
-		LLTextureCtrl* texture_ctrl;
+
+        // Are these 4 texture IDs or 4 material IDs? Who knows! Let's set the IDs on both pickers for now.
+		LLTextureCtrl* asset_ctrl;
 		std::string buffer;
 		for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
 		{
 			buffer = llformat("texture_detail_%d", i);
-			texture_ctrl = getChild<LLTextureCtrl>(buffer);
-			if(texture_ctrl)
+			asset_ctrl = getChild<LLTextureCtrl>(buffer);
+			if(asset_ctrl)
 			{
 				LL_DEBUGS() << "Detail Texture " << i << ": "
-						 << compp->getDetailTextureID(i) << LL_ENDL;
-				LLUUID tmp_id(compp->getDetailTextureID(i));
-				texture_ctrl->setImageAssetID(tmp_id);
+						 << compp->getDetailAssetID(i) << LL_ENDL;
+				LLUUID tmp_id(compp->getDetailAssetID(i));
+				asset_ctrl->setImageAssetID(tmp_id);
+			}
+		}
+		for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
+		{
+			buffer = llformat("material_detail_%d", i);
+			asset_ctrl = getChild<LLTextureCtrl>(buffer);
+			if(asset_ctrl)
+			{
+				LLUUID tmp_id(compp->getDetailAssetID(i));
+				asset_ctrl->setImageAssetID(tmp_id);
 			}
 		}
 
@@ -1499,17 +1618,45 @@ BOOL LLPanelRegionTerrainInfo::sendUpdate()
 		}
 	}
 
-	LLTextureCtrl* texture_ctrl;
+	LLTextureCtrl* asset_ctrl;
 	std::string id_str;
 	LLMessageSystem* msg = gMessageSystem;
 
+    // Use material IDs instead of texture IDs if all material IDs are set, AND the mode is set to PBR materials.
+    S32 materials_used = 0;
+    LLComboBox* material_type_ctrl = getChild<LLComboBox>("terrain_material_type");
+    if (material_type_ctrl)
+    {
+        const TerrainMaterialType material_type = material_type_from_index(material_type_ctrl->getCurrentIndex());
+        const bool is_material_selected = material_type == TerrainMaterialType::PBR_MATERIAL;
+        if (is_material_selected)
+        {
+            for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
+            {
+                buffer = llformat("material_detail_%d", i);
+                asset_ctrl = getChild<LLTextureCtrl>(buffer);
+                if(asset_ctrl && asset_ctrl->getImageAssetID().notNull())
+                {
+                    ++materials_used;
+                }
+            }
+        }
+    }
 	for(S32 i = 0; i < TERRAIN_TEXTURE_COUNT; ++i)
 	{
-		buffer = llformat("texture_detail_%d", i);
-		texture_ctrl = getChild<LLTextureCtrl>(buffer);
-		if(texture_ctrl)
+        if (materials_used == TERRAIN_TEXTURE_COUNT)
+        {
+            buffer = llformat("material_detail_%d", i);
+            asset_ctrl = getChild<LLTextureCtrl>(buffer);
+        }
+        else
+        {
+            buffer = llformat("texture_detail_%d", i);
+            asset_ctrl = getChild<LLTextureCtrl>(buffer);
+        }
+		if(asset_ctrl)
 		{
-			LLUUID tmp_id(texture_ctrl->getImageAssetID());
+			LLUUID tmp_id(asset_ctrl->getImageAssetID());
 			tmp_id.toString(id_str);
 			buffer = llformat("%d %s", i, id_str.c_str());
 			strings.push_back(buffer);
diff --git a/indra/newview/llfloaterregioninfo.h b/indra/newview/llfloaterregioninfo.h
index 3eb39b250f..91fd54fcf9 100644
--- a/indra/newview/llfloaterregioninfo.h
+++ b/indra/newview/llfloaterregioninfo.h
@@ -75,9 +75,9 @@ class LLFloaterRegionInfo : public LLFloater
 public:
 
 
-	/*virtual*/ void onOpen(const LLSD& key);
-	/*virtual*/ void onClose(bool app_quitting);
-	/*virtual*/ BOOL postBuild();
+	void onOpen(const LLSD& key) override;
+	void onClose(bool app_quitting) override;
+	BOOL postBuild() override;
 
 	static void processEstateOwnerRequest(LLMessageSystem* msg, void**);
 
@@ -98,7 +98,7 @@ public:
 	static LLPanelRegionEnvironment* getPanelEnvironment();
 
 	// from LLPanel
-	virtual void refresh();
+	void refresh() override;
 	
 	void onRegionChanged();
 	void requestRegionInfo();
@@ -144,7 +144,7 @@ public:
 	virtual bool refreshFromRegion(LLViewerRegion* region);
 	virtual bool estateUpdate(LLMessageSystem* msg) { return true; }
 	
-	virtual BOOL postBuild();
+	BOOL postBuild() override;
 	virtual void updateChild(LLUICtrl* child_ctrl);
 	
 	void enableButton(const std::string& btn_name, BOOL enable = TRUE);
@@ -184,16 +184,15 @@ public:
 		:	LLPanelRegionInfo()	{}
 	~LLPanelRegionGeneralInfo() {}
 	
-	virtual bool refreshFromRegion(LLViewerRegion* region);
+	bool refreshFromRegion(LLViewerRegion* region) override;
 	
-	// LLPanel
-	virtual BOOL postBuild();
+	BOOL postBuild() override;
 	
 	void onBtnSet();
 	void setObjBonusFactor(F32 object_bonus_factor) {mObjBonusFactor = object_bonus_factor;}
 
 protected:
-	virtual BOOL sendUpdate();
+	BOOL sendUpdate() override;
 	void onClickKick();
 	void onKickCommit(const uuid_vec_t& ids);
 	static void onClickKickAll(void* userdata);
@@ -214,13 +213,13 @@ public:
 	LLPanelRegionDebugInfo()
 		:	LLPanelRegionInfo(), mTargetAvatar() {}
 	~LLPanelRegionDebugInfo() {}
-	// LLPanel
-	virtual BOOL postBuild();
+
+	BOOL postBuild() override;
 	
-	virtual bool refreshFromRegion(LLViewerRegion* region);
+	bool refreshFromRegion(LLViewerRegion* region) override;
 	
 protected:
-	virtual BOOL sendUpdate();
+	BOOL sendUpdate() override;
 
 	void onClickChooseAvatar();
 	void callbackAvatarID(const uuid_vec_t& ids, const std::vector<LLAvatarName> names);
@@ -247,9 +246,9 @@ public:
 	LLPanelRegionTerrainInfo() : LLPanelRegionInfo() {}
 	~LLPanelRegionTerrainInfo() {}
 	
-	virtual BOOL postBuild();												// LLPanel
+	BOOL postBuild() override;
 	
-	virtual bool refreshFromRegion(LLViewerRegion* region);					// refresh local settings from region update from simulator
+    bool refreshFromRegion(LLViewerRegion* region) override;                // refresh local settings from region update from simulator
 	void setEnvControls(bool available);									// Whether environment settings are available for this region
 
 	BOOL validateTextureSizes();
@@ -257,7 +256,8 @@ public:
 
 	//static void onChangeAnything(LLUICtrl* ctrl, void* userData);			// callback for any change, to enable commit button
 	
-	virtual BOOL sendUpdate();
+    void refresh() override;
+    void onSelectMaterialType();
 
 	static void onClickDownloadRaw(void*);
 	static void onClickUploadRaw(void*);
@@ -265,6 +265,9 @@ public:
 	bool callbackBakeTerrain(const LLSD& notification, const LLSD& response);
 	bool callbackTextureHeights(const LLSD& notification, const LLSD& response);
 
+protected:
+	BOOL sendUpdate() override;
+
 private:
 	bool mConfirmedTextureHeights;
 	bool mAskedTextureHeights;
@@ -303,13 +306,12 @@ public:
 	static void updateEstateName(const std::string& name);
 	static void updateEstateOwnerName(const std::string& name);
 
-	virtual bool refreshFromRegion(LLViewerRegion* region);
-	virtual bool estateUpdate(LLMessageSystem* msg);
+	bool refreshFromRegion(LLViewerRegion* region) override;
+	bool estateUpdate(LLMessageSystem* msg) override;
 	
-	// LLPanel
-	virtual BOOL postBuild();
-	virtual void updateChild(LLUICtrl* child_ctrl);
-	virtual void refresh();
+	BOOL postBuild() override;
+	void updateChild(LLUICtrl* child_ctrl) override;
+	void refresh() override;
 
 	void refreshFromEstate();
 	
@@ -319,7 +321,7 @@ public:
 	void setOwnerName(const std::string& name);
 
 protected:
-	virtual BOOL sendUpdate();
+	BOOL sendUpdate() override;
 	// confirmation dialog callback
 	bool callbackChangeLindenEstate(const LLSD& notification, const LLSD& response);
 
@@ -339,17 +341,16 @@ public:
 	LLPanelEstateCovenant();
 	~LLPanelEstateCovenant() {}
 	
-	// LLPanel
-	virtual BOOL postBuild();
-	virtual void updateChild(LLUICtrl* child_ctrl);
-	virtual bool refreshFromRegion(LLViewerRegion* region);
-	virtual bool estateUpdate(LLMessageSystem* msg);
+	BOOL postBuild() override;
+	void updateChild(LLUICtrl* child_ctrl) override;
+	bool refreshFromRegion(LLViewerRegion* region) override;
+	bool estateUpdate(LLMessageSystem* msg) override;
 
 	// LLView overrides
 	BOOL handleDragAndDrop(S32 x, S32 y, MASK mask,
 						   BOOL drop, EDragAndDropType cargo_type,
 						   void *cargo_data, EAcceptance *accept,
-						   std::string& tooltip_msg);
+						   std::string& tooltip_msg) override;
 	static bool confirmChangeCovenantCallback(const LLSD& notification, const LLSD& response);
 	static void resetCovenantID(void* userdata);
 	static bool confirmResetCovenantCallback(const LLSD& notification, const LLSD& response);
@@ -382,7 +383,7 @@ public:
 	} EAssetStatus;
 
 protected:
-	virtual BOOL sendUpdate();
+	BOOL sendUpdate() override;
 	LLTextBox*				mEstateNameText;
 	LLTextBox*				mEstateOwnerText;
 	LLTextBox*				mLastModifiedText;
@@ -401,16 +402,19 @@ class LLPanelRegionExperiences : public LLPanelRegionInfo
 
 public:
 	LLPanelRegionExperiences(){}
-	/*virtual*/ BOOL postBuild();
-	virtual BOOL sendUpdate();
+	BOOL postBuild() override;
 	
 	static bool experienceCoreConfirm(const LLSD& notification, const LLSD& response);
 	static void sendEstateExperienceDelta(U32 flags, const LLUUID& agent_id);
 
 	static void infoCallback(LLHandle<LLPanelRegionExperiences> handle, const LLSD& content);
-	bool refreshFromRegion(LLViewerRegion* region);
+	bool refreshFromRegion(LLViewerRegion* region) override;
 	void sendPurchaseRequest()const;
 	void processResponse( const LLSD& content );
+
+protected:
+	BOOL sendUpdate() override;
+
 private:
 	void refreshRegionExperiences();
 
@@ -435,8 +439,8 @@ class LLPanelEstateAccess : public LLPanelRegionInfo
 public:
 	LLPanelEstateAccess();
 
-	virtual BOOL postBuild();
-	virtual void updateChild(LLUICtrl* child_ctrl);
+	BOOL postBuild() override;
+	void updateChild(LLUICtrl* child_ctrl) override;
 
 	void updateControls(LLViewerRegion* region);
 	void updateLists();
@@ -444,7 +448,7 @@ public:
 	void setPendingUpdate(bool pending) { mPendingUpdate = pending; }
 	bool getPendingUpdate() { return mPendingUpdate; }
 
-	virtual bool refreshFromRegion(LLViewerRegion* region);
+	bool refreshFromRegion(LLViewerRegion* region) override;
 
 private:
 	void onClickAddAllowedAgent();
diff --git a/indra/newview/llgltfmateriallist.cpp b/indra/newview/llgltfmateriallist.cpp
index 92c58a2dbc..a9216ae656 100644
--- a/indra/newview/llgltfmateriallist.cpp
+++ b/indra/newview/llgltfmateriallist.cpp
@@ -471,7 +471,7 @@ void LLGLTFMaterialList::onAssetLoadComplete(const LLUUID& id, LLAssetType::ETyp
     if (status != LL_ERR_NOERR)
     {
         LL_WARNS("GLTF") << "Error getting material asset data: " << LLAssetStorage::getErrorString(status) << " (" << status << ")" << LL_ENDL;
-        asset_data->mMaterial->materialComplete();
+        asset_data->mMaterial->materialComplete(false);
         delete asset_data;
     }
     else
@@ -556,7 +556,7 @@ void LLGLTFMaterialList::onAssetLoadComplete(const LLUUID& id, LLAssetType::ETyp
                 LL_DEBUGS("GLTF") << "Failed to get material " << id << LL_ENDL;
             }
 
-            asset_data->mMaterial->materialComplete();
+            asset_data->mMaterial->materialComplete(true);
 
             delete asset_data;
         });
diff --git a/indra/newview/llgltfmaterialpreviewmgr.cpp b/indra/newview/llgltfmaterialpreviewmgr.cpp
new file mode 100644
index 0000000000..901db87eed
--- /dev/null
+++ b/indra/newview/llgltfmaterialpreviewmgr.cpp
@@ -0,0 +1,566 @@
+/**
+ * @file llgltfmaterialpreviewmgr.cpp
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "llviewerprecompiledheaders.h"
+
+#include "llgltfmaterialpreviewmgr.h"
+
+#include <memory>
+#include <vector>
+
+#include "llavatarappearancedefines.h"
+#include "llenvironment.h"
+#include "llselectmgr.h"
+#include "llviewercamera.h"
+#include "llviewercontrol.h"
+#include "llviewerobject.h"
+#include "llviewershadermgr.h"
+#include "llviewertexturelist.h"
+#include "llviewerwindow.h"
+#include "llvolumemgr.h"
+#include "pipeline.h"
+
+LLGLTFMaterialPreviewMgr gGLTFMaterialPreviewMgr;
+
+namespace
+{
+    constexpr S32 FULLY_LOADED = 0;
+    constexpr S32 NOT_LOADED = 99;
+};
+
+LLGLTFPreviewTexture::MaterialLoadLevels::MaterialLoadLevels()
+{
+    for (U32 i = 0; i < LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT; ++i)
+    {
+        levels[i] = NOT_LOADED;
+    }
+}
+
+S32& LLGLTFPreviewTexture::MaterialLoadLevels::operator[](size_t i)
+{
+    llassert(i >= 0 && i < LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT);
+    return levels[i];
+}
+
+const S32& LLGLTFPreviewTexture::MaterialLoadLevels::operator[](size_t i) const
+{
+    llassert(i >= 0 && i < LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT);
+    return levels[i];
+}
+
+bool LLGLTFPreviewTexture::MaterialLoadLevels::operator<(const MaterialLoadLevels& other) const
+{
+    bool less = false;
+    for (U32 i = 0; i < LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT; ++i)
+    {
+        if (((*this)[i] > other[i])) { return false; }
+        less = less || ((*this)[i] < other[i]);
+    }
+    return less;
+}
+
+bool LLGLTFPreviewTexture::MaterialLoadLevels::operator>(const MaterialLoadLevels& other) const
+{
+    bool great = false;
+    for (U32 i = 0; i < LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT; ++i)
+    {
+        if (((*this)[i] < other[i])) { return false; }
+        great = great || ((*this)[i] > other[i]);
+    }
+    return great;
+}
+
+namespace
+{
+    void fetch_texture_for_ui(LLPointer<LLViewerFetchedTexture>& img, const LLUUID& id)
+    {
+        if (!img && id.notNull())
+        {
+            if (LLAvatarAppearanceDefines::LLAvatarAppearanceDictionary::isBakedImageId(id))
+            {
+                LLViewerObject* obj = LLSelectMgr::getInstance()->getSelection()->getFirstObject();
+                if (obj)
+                {
+                    LLViewerTexture* viewerTexture = obj->getBakedTextureForMagicId(id);
+                    img = viewerTexture ? dynamic_cast<LLViewerFetchedTexture*>(viewerTexture) : NULL;
+                }
+            }
+            else
+            {
+                img = LLViewerTextureManager::getFetchedTexture(id, FTT_DEFAULT, TRUE, LLGLTexture::BOOST_NONE, LLViewerTexture::LOD_TEXTURE);
+            }
+        }
+        if (img)
+        {
+            img->setBoostLevel(LLGLTexture::BOOST_PREVIEW);
+            img->forceToSaveRawImage(0);
+        }
+    };
+
+    // *NOTE: Does not use the same conventions as texture discard level. Lower is better.
+    S32 get_texture_load_level(const LLPointer<LLViewerFetchedTexture>& texture)
+    {
+        if (!texture) { return FULLY_LOADED; }
+        const S32 raw_level = texture->getDiscardLevel();
+        if (raw_level < 0) { return NOT_LOADED; }
+        return raw_level;
+    }
+
+    LLGLTFPreviewTexture::MaterialLoadLevels get_material_load_levels(LLFetchedGLTFMaterial& material)
+    {
+        llassert(!material.isFetching());
+
+        using MaterialTextures = LLPointer<LLViewerFetchedTexture>*[LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT];
+
+        MaterialTextures textures;
+
+        textures[LLGLTFMaterial::GLTF_TEXTURE_INFO_BASE_COLOR] = &material.mBaseColorTexture;
+        textures[LLGLTFMaterial::GLTF_TEXTURE_INFO_NORMAL] = &material.mNormalTexture;
+        textures[LLGLTFMaterial::GLTF_TEXTURE_INFO_METALLIC_ROUGHNESS] = &material.mMetallicRoughnessTexture;
+        textures[LLGLTFMaterial::GLTF_TEXTURE_INFO_EMISSIVE] = &material.mEmissiveTexture;
+
+        LLGLTFPreviewTexture::MaterialLoadLevels levels;
+
+        for (U32 i = 0; i < LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT; ++i)
+        {
+            fetch_texture_for_ui(*textures[i], material.mTextureId[i]);
+            levels[i] = get_texture_load_level(*textures[i]);
+        }
+
+        return levels;
+    }
+
+    // Is the material loaded enough to start rendering a preview?
+    bool is_material_loaded_enough_for_ui(LLFetchedGLTFMaterial& material)
+    {
+        if (material.isFetching())
+        {
+            return false;
+        }
+
+        LLGLTFPreviewTexture::MaterialLoadLevels levels = get_material_load_levels(material);
+
+        for (U32 i = 0; i < LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT; ++i)
+        {
+            if (levels[i] == NOT_LOADED)
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+};  // namespace
+
+LLGLTFPreviewTexture::LLGLTFPreviewTexture(LLPointer<LLFetchedGLTFMaterial> material, S32 width)
+    : LLViewerDynamicTexture(width, width, 4, EOrder::ORDER_MIDDLE, FALSE)
+    , mGLTFMaterial(material)
+{
+}
+
+// static
+LLPointer<LLGLTFPreviewTexture> LLGLTFPreviewTexture::create(LLPointer<LLFetchedGLTFMaterial> material)
+{
+    return new LLGLTFPreviewTexture(material, LLPipeline::MAX_BAKE_WIDTH);
+}
+
+void LLGLTFPreviewTexture::preRender(BOOL clear_depth)
+{
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_UI;
+
+    MaterialLoadLevels current_load = get_material_load_levels(*mGLTFMaterial.get());
+    if (current_load < mBestLoad)
+    {
+        mShouldRender = true;
+        mBestLoad = current_load;
+    }
+
+    if (!mShouldRender) { return; }
+
+    LLViewerDynamicTexture::preRender(clear_depth);
+}
+
+
+namespace {
+
+struct GLTFPreviewModel
+{
+    GLTFPreviewModel(LLPointer<LLDrawInfo>& info, const LLMatrix4& mat)
+    : mDrawInfo(info)
+    , mModelMatrix(mat)
+    {
+        mDrawInfo->mModelMatrix = &mModelMatrix;
+    }
+    GLTFPreviewModel(GLTFPreviewModel&) = delete;
+    ~GLTFPreviewModel()
+    {
+        // No model matrix necromancy
+        llassert(gGLLastMatrix != &mModelMatrix);
+        gGLLastMatrix = nullptr;
+    }
+    LLPointer<LLDrawInfo> mDrawInfo;
+    LLMatrix4 mModelMatrix; // Referenced by mDrawInfo
+};
+
+using PreviewSpherePart = std::unique_ptr<GLTFPreviewModel>;
+using PreviewSphere = std::vector<PreviewSpherePart>;
+
+// Like LLVolumeGeometryManager::registerFace but without batching or too-many-indices/vertices checking.
+PreviewSphere create_preview_sphere(LLPointer<LLFetchedGLTFMaterial>& material, const LLMatrix4& model_matrix)
+{
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_UI;
+
+    const LLColor4U vertex_color(material->mBaseColor);
+
+    LLPrimitive prim;
+    prim.init_primitive(LL_PCODE_VOLUME);
+    LLVolumeParams params;
+    params.setType(LL_PCODE_PROFILE_CIRCLE_HALF, LL_PCODE_PATH_CIRCLE);
+    params.setBeginAndEndS(0.f, 1.f);
+    params.setBeginAndEndT(0.f, 1.f);
+    params.setRatio(1, 1);
+    params.setShear(0, 0);
+    constexpr auto MAX_LOD = LLVolumeLODGroup::NUM_LODS - 1;
+    prim.setVolume(params, MAX_LOD);
+
+    LLVolume* volume = prim.getVolume();
+    llassert(volume);
+    for (LLVolumeFace& face : volume->getVolumeFaces())
+    {
+        face.createTangents();
+    }
+
+    PreviewSphere preview_sphere;
+    preview_sphere.reserve(volume->getNumFaces());
+
+    LLPointer<LLVertexBuffer> buf = new LLVertexBuffer(
+        LLVertexBuffer::MAP_VERTEX |
+        LLVertexBuffer::MAP_NORMAL |
+        LLVertexBuffer::MAP_TEXCOORD0 |
+        LLVertexBuffer::MAP_COLOR |
+        LLVertexBuffer::MAP_TANGENT
+    );
+    U32 nv = 0;
+    U32 ni = 0;
+    for (LLVolumeFace& face : volume->getVolumeFaces())
+    {
+        nv += face.mNumVertices;
+        ni += face.mNumIndices;
+    }
+    buf->allocateBuffer(nv, ni);
+
+    // UV hacks
+    // Higher factor helps to see more details on the preview sphere
+    const LLVector2 uv_factor(2.0f, 2.0f);
+    // Offset places center of material in center of view
+    const LLVector2 uv_offset(-0.5f, -0.5f);
+
+    LLStrider<U16> indices;
+    LLStrider<LLVector4a> positions;
+    LLStrider<LLVector4a> normals;
+    LLStrider<LLVector2> texcoords;
+    LLStrider<LLColor4U> colors;
+    LLStrider<LLVector4a> tangents;
+	buf->getIndexStrider(indices);
+	buf->getVertexStrider(positions);
+	buf->getNormalStrider(normals);
+	buf->getTexCoord0Strider(texcoords);
+	buf->getColorStrider(colors);
+	buf->getTangentStrider(tangents);
+    U32 index_offset = 0;
+    U32 vertex_offset = 0;
+    for (const LLVolumeFace& face : volume->getVolumeFaces())
+    {
+        for (S32 i = 0; i < face.mNumIndices; ++i)
+        {
+            *indices++ = face.mIndices[i] + vertex_offset;
+        }
+        for (S32 v = 0; v < face.mNumVertices; ++v)
+        {
+            *positions++ = face.mPositions[v];
+            *normals++ = face.mNormals[v];
+            LLVector2 uv(face.mTexCoords[v]);
+            uv.scaleVec(uv_factor);
+            uv += uv_offset;
+            *texcoords++ = uv;
+            *colors++ = vertex_color;
+            *tangents++ = face.mTangents[v];
+        }
+
+        constexpr LLViewerTexture* no_media = nullptr;
+        LLPointer<LLDrawInfo> info = new LLDrawInfo(U16(vertex_offset), U16(vertex_offset + face.mNumVertices - 1), face.mNumIndices, index_offset, no_media, buf.get());
+        info->mGLTFMaterial = material;
+        preview_sphere.emplace_back(std::make_unique<GLTFPreviewModel>(info, model_matrix));
+        index_offset += face.mNumIndices;
+        vertex_offset += face.mNumVertices;
+    }
+
+    buf->unmapBuffer();
+
+    return preview_sphere;
+}
+
+void set_preview_sphere_material(PreviewSphere& preview_sphere, LLPointer<LLFetchedGLTFMaterial>& material)
+{
+    llassert(!preview_sphere.empty());
+    if (preview_sphere.empty()) { return; }
+
+    const LLColor4U vertex_color(material->mBaseColor);
+
+    // See comments about unmapBuffer in llvertexbuffer.h
+    for (PreviewSpherePart& part : preview_sphere)
+    {
+        LLDrawInfo* info = part->mDrawInfo.get();
+        info->mGLTFMaterial = material;
+        LLVertexBuffer* buf = info->mVertexBuffer.get();
+        LLStrider<LLColor4U> colors;
+        const S32 count = info->mEnd - info->mStart + 1;
+        buf->getColorStrider(colors, info->mStart, count);
+        for (S32 i = 0; i < count; ++i)
+        {
+            *colors++ = vertex_color;
+        }
+        buf->unmapBuffer();
+    }
+}
+
+PreviewSphere& get_preview_sphere(LLPointer<LLFetchedGLTFMaterial>& material, const LLMatrix4& model_matrix)
+{
+    static PreviewSphere preview_sphere;
+    if (preview_sphere.empty())
+    {
+        preview_sphere = create_preview_sphere(material, model_matrix);
+    }
+    else
+    {
+        set_preview_sphere_material(preview_sphere, material);
+    }
+    return preview_sphere;
+}
+
+// Final, direct modifications to shader constants, just before render
+void fixup_shader_constants(LLGLSLShader& shader)
+{
+    // Sunlight intensity of 0 no matter what
+    shader.uniform1i(LLShaderMgr::SUN_UP_FACTOR, 1);
+    shader.uniform3fv(LLShaderMgr::SUNLIGHT_COLOR, 1, LLColor3::white.mV);
+    shader.uniform1f(LLShaderMgr::DENSITY_MULTIPLIER, 0.0f);
+
+    // Ignore sun shadow (if enabled)
+    for (U32 i = 0; i < 6; i++)
+    {
+        const S32 channel = shader.getTextureChannel(LLShaderMgr::DEFERRED_SHADOW0+i);
+        if (channel != -1)
+        {
+            gGL.getTexUnit(channel)->bind(LLViewerFetchedTexture::sWhiteImagep, TRUE);
+        }
+    }
+}
+
+// Set a variable to a value temporarily, and restor the variable's old value
+// when this object leaves scope.
+template<typename T>
+struct SetTemporarily
+{
+    T* mRef;
+    T mOldVal;
+    SetTemporarily(T* var, T temp_val)
+    {
+        mRef = var;
+        mOldVal = *mRef;
+        *mRef = temp_val;
+    }
+    ~SetTemporarily()
+    {
+        *mRef = mOldVal;
+    }
+};
+
+}; // namespace
+
+BOOL LLGLTFPreviewTexture::render()
+{
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_UI;
+
+    if (!mShouldRender) { return FALSE; }
+
+    glClearColor(0, 0, 0, 0);
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    
+    LLGLDepthTest(GL_FALSE);
+    LLGLDisable stencil(GL_STENCIL_TEST);
+    LLGLDisable scissor(GL_SCISSOR_TEST);
+    SetTemporarily<bool> no_dof(&LLPipeline::RenderDepthOfField, false);
+    SetTemporarily<bool> no_glow(&LLPipeline::sRenderGlow, false);
+    SetTemporarily<bool> no_ssr(&LLPipeline::RenderScreenSpaceReflections, false);
+    SetTemporarily<U32> no_fxaa(&LLPipeline::RenderFSAASamples, U32(0));
+    SetTemporarily<LLPipeline::RenderTargetPack*> use_auxiliary_render_target(&gPipeline.mRT, &gPipeline.mAuxillaryRT);
+
+    LLVector3 light_dir3(1.0f, 1.0f, 1.0f);
+    light_dir3.normalize();
+    const LLVector4 light_dir = LLVector4(light_dir3, 0);
+    const S32 old_local_light_count = gSavedSettings.get<S32>("RenderLocalLightCount");
+    gSavedSettings.set<S32>("RenderLocalLightCount", 0);
+
+    gPipeline.mReflectionMapManager.forceDefaultProbeAndUpdateUniforms();
+
+    LLViewerCamera camera;
+
+    // Calculate the object distance at which the object of a given radius will
+    // span the partial width of the screen given by fill_ratio.
+    // Assume the primitive has a scale of 1 (this is the default).
+    constexpr F32 fill_ratio = 0.8f;
+    constexpr F32 object_radius = 0.5f;
+    const F32 object_distance = (object_radius / fill_ratio) * tan(camera.getDefaultFOV());
+    // Negative coordinate shows the textures on the sphere right-side up, when
+    // combined with the UV hacks in create_preview_sphere
+    const LLVector3 object_position(0.0, -object_distance, 0.0);
+    LLMatrix4 object_transform;
+    object_transform.translate(object_position);
+
+    // Set up camera and viewport
+    const LLVector3 origin(0.0, 0.0, 0.0);
+    camera.lookAt(origin, object_position);
+    camera.setAspect(mFullHeight / mFullWidth);
+    const LLRect texture_rect(0, mFullHeight, mFullWidth, 0);
+    camera.setPerspective(NOT_FOR_SELECTION, texture_rect.mLeft, texture_rect.mBottom, texture_rect.getWidth(), texture_rect.getHeight(), FALSE, camera.getNear(), MAX_FAR_CLIP*2.f);
+
+    // Generate sphere object on-the-fly. Discard afterwards. (Vertex buffer is
+    // discarded, but the sphere should be cached in LLVolumeMgr.)
+    PreviewSphere& preview_sphere = get_preview_sphere(mGLTFMaterial, object_transform);
+
+    gPipeline.setupHWLights();
+    glh::matrix4f mat = copy_matrix(gGLModelView);
+    glh::vec4f transformed_light_dir(light_dir.mV);
+    mat.mult_matrix_vec(transformed_light_dir);
+    SetTemporarily<LLVector4> force_sun_direction_high_graphics(&gPipeline.mTransformedSunDir, LLVector4(transformed_light_dir.v));
+    // Override lights to ensure the sun is always shining from a certain direction (low graphics)
+    // See also force_sun_direction_high_graphics and fixup_shader_constants
+    {
+        LLLightState* light = gGL.getLight(0);
+        light->setPosition(light_dir);
+        constexpr bool sun_up = true;
+        light->setSunPrimary(sun_up);
+    }
+
+    LLRenderTarget& screen = gPipeline.mAuxillaryRT.screen;
+
+    // *HACK: Force reset of the model matrix
+    gGLLastMatrix = nullptr;
+
+#if 0
+    if (mGLTFMaterial->mAlphaMode == LLGLTFMaterial::ALPHA_MODE_OPAQUE || mGLTFMaterial->mAlphaMode == LLGLTFMaterial::ALPHA_MODE_MASK)
+    {
+        // *TODO: Opaque/alpha mask rendering
+    }
+    else
+#endif
+    {
+        // Alpha blend rendering
+
+        screen.bindTarget();
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+        LLGLSLShader& shader = gDeferredPBRAlphaProgram;
+
+        gPipeline.bindDeferredShader(shader);
+        fixup_shader_constants(shader);
+
+        for (PreviewSpherePart& part : preview_sphere)
+        {
+            LLRenderPass::pushGLTFBatch(*part->mDrawInfo);
+        }
+
+        gPipeline.unbindDeferredShader(shader);
+
+        screen.flush();
+    }
+
+    gPipeline.copyScreenSpaceReflections(&screen, &gPipeline.mSceneMap);
+    gPipeline.generateLuminance(&screen, &gPipeline.mLuminanceMap);
+    gPipeline.generateExposure(&gPipeline.mLuminanceMap, &gPipeline.mExposureMap);
+    gPipeline.gammaCorrect(&screen, &gPipeline.mPostMap);
+    LLVertexBuffer::unbind();
+    gPipeline.generateGlow(&gPipeline.mPostMap);
+    gPipeline.combineGlow(&gPipeline.mPostMap, &screen);
+	gPipeline.renderDoF(&screen, &gPipeline.mPostMap);
+	gPipeline.applyFXAA(&gPipeline.mPostMap, &screen);
+
+    // Final render
+
+	gDeferredPostNoDoFProgram.bind();
+
+	// From LLPipeline::renderFinalize: "Whatever is last in the above post processing chain should _always_ be rendered directly here.  If not, expect problems."
+	gDeferredPostNoDoFProgram.bindTexture(LLShaderMgr::DEFERRED_DIFFUSE, &screen);
+	gDeferredPostNoDoFProgram.bindTexture(LLShaderMgr::DEFERRED_DEPTH, mBoundTarget, true);
+
+	{
+		LLGLDepthTest depth_test(GL_TRUE, GL_TRUE, GL_ALWAYS);
+		gPipeline.mScreenTriangleVB->setBuffer();
+		gPipeline.mScreenTriangleVB->drawArrays(LLRender::TRIANGLES, 0, 3);
+	}
+
+	gDeferredPostNoDoFProgram.unbind();
+
+    // Clean up
+    gPipeline.setupHWLights();
+    gPipeline.mReflectionMapManager.forceDefaultProbeAndUpdateUniforms(false);
+    gSavedSettings.set<S32>("RenderLocalLightCount", old_local_light_count);
+
+    return TRUE;
+}
+
+void LLGLTFPreviewTexture::postRender(BOOL success)
+{
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_UI;
+
+    if (!mShouldRender) { return; }
+    mShouldRender = false;
+
+    LLViewerDynamicTexture::postRender(success);
+}
+
+LLPointer<LLViewerTexture> LLGLTFMaterialPreviewMgr::getPreview(LLPointer<LLFetchedGLTFMaterial> &material)
+{
+    if (!material)
+    {
+        return nullptr;
+    }
+
+    static LLCachedControl<bool> sUIPreviewMaterial(gSavedSettings, "UIPreviewMaterial", false);
+    if (!sUIPreviewMaterial)
+    {
+        fetch_texture_for_ui(material->mBaseColorTexture, material->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_BASE_COLOR]);
+        return material->mBaseColorTexture;
+    }
+
+    if (!is_material_loaded_enough_for_ui(*material))
+    {
+        return nullptr;
+    }
+
+    return LLGLTFPreviewTexture::create(material);
+}
diff --git a/indra/newview/llgltfmaterialpreviewmgr.h b/indra/newview/llgltfmaterialpreviewmgr.h
new file mode 100644
index 0000000000..cc40a6f2e2
--- /dev/null
+++ b/indra/newview/llgltfmaterialpreviewmgr.h
@@ -0,0 +1,82 @@
+/**
+ * @file llgltfmaterialpreviewmgr.h
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#pragma once
+
+#include "lldrawpool.h"
+#include "lldynamictexture.h"
+#include "llfetchedgltfmaterial.h"
+#include "llsingleton.h"
+#include "lltexture.h"
+
+class LLGLTFPreviewTexture : public LLViewerDynamicTexture
+{
+protected:
+    LLGLTFPreviewTexture(LLPointer<LLFetchedGLTFMaterial> material, S32 width);
+
+public:
+    // Width scales with size of material's textures
+    static LLPointer<LLGLTFPreviewTexture> create(LLPointer<LLFetchedGLTFMaterial> material);
+
+    BOOL needsRender() override { return mNeedsRender; }
+    void preRender(BOOL clear_depth = TRUE) override;
+    BOOL render() override;
+    void postRender(BOOL success) override;
+
+    struct MaterialLoadLevels
+    {
+        S32 levels[LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT];
+
+        MaterialLoadLevels();
+
+        S32& operator[](size_t i);
+
+        const S32& operator[](size_t i) const;
+
+        // Less is better
+        // Returns false if lhs is not strictly less or equal for all levels
+        bool operator<(const MaterialLoadLevels& other) const;
+
+        // Less is better
+        // Returns false if lhs is not strictly greater or equal for all levels
+        bool operator>(const MaterialLoadLevels& other) const;
+    };
+
+private:
+    LLPointer<LLFetchedGLTFMaterial> mGLTFMaterial;
+    bool mNeedsRender = true;
+    bool mShouldRender = true;
+    MaterialLoadLevels mBestLoad;
+};
+
+class LLGLTFMaterialPreviewMgr
+{
+  public:
+    // Returns null if the material is not loaded yet.
+    // *NOTE: User should cache the texture if the same material is being previewed
+    LLPointer<LLViewerTexture> getPreview(LLPointer<LLFetchedGLTFMaterial> &material);
+};
+
+extern LLGLTFMaterialPreviewMgr gGLTFMaterialPreviewMgr;
diff --git a/indra/newview/llheroprobemanager.cpp b/indra/newview/llheroprobemanager.cpp
new file mode 100644
index 0000000000..2a81919856
--- /dev/null
+++ b/indra/newview/llheroprobemanager.cpp
@@ -0,0 +1,559 @@
+/**
+ * @file LLHeroProbeManager.cpp
+ * @brief LLHeroProbeManager class implementation
+ *
+ * $LicenseInfo:firstyear=2022&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2022, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "llviewerprecompiledheaders.h"
+
+#include "llheroprobemanager.h"
+#include "llreflectionmapmanager.h"
+#include "llviewercamera.h"
+#include "llspatialpartition.h"
+#include "llviewerregion.h"
+#include "pipeline.h"
+#include "llviewershadermgr.h"
+#include "llviewercontrol.h"
+#include "llenvironment.h"
+#include "llstartup.h"
+#include "llagent.h"
+#include "llagentcamera.h"
+#include "llviewerwindow.h"
+#include "llviewerjoystick.h"
+#include "llviewermediafocus.h"
+
+extern BOOL gCubeSnapshot;
+extern BOOL gTeleportDisplay;
+
+// get the next highest power of two of v (or v if v is already a power of two)
+//defined in llvertexbuffer.cpp
+extern U32 nhpo2(U32 v);
+
+static void touch_default_probe(LLReflectionMap* probe)
+{
+    if (LLViewerCamera::getInstance())
+    {
+        LLVector3 origin = LLViewerCamera::getInstance()->getOrigin();
+        origin.mV[2] += 64.f;
+
+        probe->mOrigin.load3(origin.mV);
+    }
+}
+
+LLHeroProbeManager::LLHeroProbeManager()
+{
+}
+
+// helper class to seed octree with probes
+void LLHeroProbeManager::update()
+{
+    if (!LLPipeline::RenderMirrors || gTeleportDisplay || LLStartUp::getStartupState() < STATE_PRECACHE)
+    {
+        return;
+    }
+
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
+    llassert(!gCubeSnapshot); // assert a snapshot is not in progress
+    if (LLAppViewer::instance()->logoutRequestSent())
+    {
+        return;
+    }
+
+    initReflectionMaps();
+
+    if (!mRenderTarget.isComplete())
+    {
+        U32 color_fmt = GL_RGBA16F;
+        U32 targetRes = mProbeResolution; // super sample
+        mRenderTarget.allocate(targetRes, targetRes, color_fmt, true);
+    }
+
+    if (mMipChain.empty())
+    {
+        U32 res = mProbeResolution;
+        U32 count = log2((F32)res) + 0.5f;
+
+        mMipChain.resize(count);
+        for (int i = 0; i < count; ++i)
+        {
+            mMipChain[i].allocate(res, res, GL_RGBA16F);
+            res /= 2;
+        }
+    }
+
+    llassert(mProbes[0] == mDefaultProbe);
+
+    LLVector4a probe_pos;
+    LLVector3 camera_pos = LLViewerCamera::instance().mOrigin;
+    F32        near_clip  = 0.1f;
+    if (mHeroVOList.size() > 0)
+    {
+        // Find our nearest hero candidate.
+
+        float last_distance = 99999.f;
+
+        for (auto vo : mHeroVOList)
+        {
+            if (vo && !vo->isDead())
+            {
+                if (vo->mDrawable.notNull())
+                {
+                    if (vo->mDrawable->mDistanceWRTCamera < last_distance)
+                    {
+                        mNearestHero = vo;
+                        last_distance = vo->mDrawable->mDistanceWRTCamera;
+                    }
+                }
+                else
+                {
+                    // Valid drawables only please.  Unregister this one.
+                    unregisterViewerObject(vo);
+                }
+            }
+            else
+            {
+                unregisterViewerObject(vo);
+            }
+        }
+
+        if (mNearestHero != nullptr && !mNearestHero->isDead() && mNearestHero->mDrawable.notNull())
+        {
+            LLVector3 hero_pos = mNearestHero->getPositionAgent();
+            LLVector3 face_normal = LLVector3(0, 0, 1);
+
+            face_normal *= mNearestHero->mDrawable->getXform()->getWorldRotation();
+            face_normal.normalize();
+
+            LLVector3 offset = camera_pos - hero_pos;
+            LLVector3 project = face_normal * (offset * face_normal);
+            LLVector3 reject  = offset - project;
+            LLVector3 point   = (reject - project) + hero_pos;
+
+            mCurrentClipPlane.setVec(hero_pos, face_normal);
+            mMirrorPosition = hero_pos;
+            mMirrorNormal   = face_normal;
+        
+
+            probe_pos.load3(point.mV);
+        }
+        else
+        { 
+            mNearestHero = nullptr;
+        }
+            
+        mHeroProbeStrength = 1;
+    }
+    else
+    {
+        probe_pos.load3(camera_pos.mV);
+    }
+    
+    
+    static LLCachedControl<S32> sDetail(gSavedSettings, "RenderHeroReflectionProbeDetail", -1);
+    static LLCachedControl<S32> sLevel(gSavedSettings, "RenderHeroReflectionProbeLevel", 3);
+
+    {
+        LL_PROFILE_ZONE_NAMED_CATEGORY_DISPLAY("hpmu - realtime");
+        // Probe 0 is always our mirror probe.
+        mProbes[0]->mOrigin = probe_pos;
+        
+        bool radiance_pass = gPipeline.mReflectionMapManager.isRadiancePass();
+        
+        gPipeline.mReflectionMapManager.mRadiancePass = true;
+        mRenderingMirror = true;
+        for (U32 j = 0; j < mProbes.size(); j++)
+        {
+            for (U32 i = 0; i < 6; ++i)
+            {
+                updateProbeFace(mProbes[j], i, near_clip);
+            }
+        }
+        mRenderingMirror = false;
+        
+        gPipeline.mReflectionMapManager.mRadiancePass = radiance_pass;
+    }
+}
+
+// Do the reflection map update render passes.
+// For every 12 calls of this function, one complete reflection probe radiance map and irradiance map is generated
+// First six passes render the scene with direct lighting only into a scratch space cube map at the end of the cube map array and generate 
+// a simple mip chain (not convolution filter).
+// At the end of these passes, an irradiance map is generated for this probe and placed into the irradiance cube map array at the index for this probe
+// The next six passes render the scene with both radiance and irradiance into the same scratch space cube map and generate a simple mip chain.
+// At the end of these passes, a radiance map is generated for this probe and placed into the radiance cube map array at the index for this probe.
+// In effect this simulates single-bounce lighting.
+void LLHeroProbeManager::updateProbeFace(LLReflectionMap* probe, U32 face, F32 near_clip)
+{
+    // hacky hot-swap of camera specific render targets
+    gPipeline.mRT = &gPipeline.mHeroProbeRT;
+
+    probe->update(mRenderTarget.getWidth(), face, true, near_clip);
+    
+    gPipeline.mRT = &gPipeline.mMainRT;
+
+    S32 sourceIdx = mReflectionProbeCount;
+    
+    
+    // Unlike the reflectionmap manager, all probes are considered "realtime" for hero probes.
+    sourceIdx += 1;
+
+    gGL.setColorMask(true, true);
+    LLGLDepthTest depth(GL_FALSE, GL_FALSE);
+    LLGLDisable cull(GL_CULL_FACE);
+    LLGLDisable blend(GL_BLEND);
+    
+    // downsample to placeholder map
+    {
+        gGL.matrixMode(gGL.MM_MODELVIEW);
+        gGL.pushMatrix();
+        gGL.loadIdentity();
+
+        gGL.matrixMode(gGL.MM_PROJECTION);
+        gGL.pushMatrix();
+        gGL.loadIdentity();
+
+        gGL.flush();
+        U32 res = mProbeResolution * 2;
+
+        static LLStaticHashedString resScale("resScale");
+        static LLStaticHashedString direction("direction");
+        static LLStaticHashedString znear("znear");
+        static LLStaticHashedString zfar("zfar");
+
+        LLRenderTarget *screen_rt = &gPipeline.mHeroProbeRT.screen;
+        LLRenderTarget *depth_rt  = &gPipeline.mHeroProbeRT.deferredScreen;
+        
+        // perform a gaussian blur on the super sampled render before downsampling
+        {
+            gGaussianProgram.bind();
+            gGaussianProgram.uniform1f(resScale, 1.f / (mProbeResolution * 2));
+            S32 diffuseChannel = gGaussianProgram.enableTexture(LLShaderMgr::DEFERRED_DIFFUSE, LLTexUnit::TT_TEXTURE);
+
+            // horizontal
+            gGaussianProgram.uniform2f(direction, 1.f, 0.f);
+            gGL.getTexUnit(diffuseChannel)->bind(screen_rt);
+            mRenderTarget.bindTarget();
+            gPipeline.mScreenTriangleVB->setBuffer();
+            gPipeline.mScreenTriangleVB->drawArrays(LLRender::TRIANGLES, 0, 3);
+            mRenderTarget.flush();
+
+            // vertical
+            gGaussianProgram.uniform2f(direction, 0.f, 1.f);
+            gGL.getTexUnit(diffuseChannel)->bind(&mRenderTarget);
+            screen_rt->bindTarget();
+            gPipeline.mScreenTriangleVB->setBuffer();
+            gPipeline.mScreenTriangleVB->drawArrays(LLRender::TRIANGLES, 0, 3);
+            screen_rt->flush();
+            gGaussianProgram.unbind();
+        }
+
+        S32 mips = log2((F32)mProbeResolution) + 0.5f;
+
+        gReflectionMipProgram.bind();
+        S32 diffuseChannel = gReflectionMipProgram.enableTexture(LLShaderMgr::DEFERRED_DIFFUSE, LLTexUnit::TT_TEXTURE);
+        S32 depthChannel   = gReflectionMipProgram.enableTexture(LLShaderMgr::DEFERRED_DEPTH, LLTexUnit::TT_TEXTURE);
+
+        for (int i = 0; i < mMipChain.size(); ++i)
+        {
+            LL_PROFILE_GPU_ZONE("probe mip");
+            mMipChain[i].bindTarget();
+            if (i == 0)
+            {
+                gGL.getTexUnit(diffuseChannel)->bind(screen_rt);
+            }
+            else
+            {
+                gGL.getTexUnit(diffuseChannel)->bind(&(mMipChain[i - 1]));
+            }
+
+            gGL.getTexUnit(depthChannel)->bind(depth_rt, true);
+            
+            gReflectionMipProgram.uniform1f(resScale, 1.f / (mProbeResolution * 2));
+            gReflectionMipProgram.uniform1f(znear, probe->getNearClip());
+            gReflectionMipProgram.uniform1f(zfar, MAX_FAR_CLIP);
+            
+            gPipeline.mScreenTriangleVB->setBuffer();
+            gPipeline.mScreenTriangleVB->drawArrays(LLRender::TRIANGLES, 0, 3);
+            
+            res /= 2;
+
+            S32 mip = i - (mMipChain.size() - mips);
+
+            if (mip >= 0)
+            {
+                LL_PROFILE_GPU_ZONE("probe mip copy");
+                mTexture->bind(0);
+
+                glCopyTexSubImage3D(GL_TEXTURE_CUBE_MAP_ARRAY, mip, 0, 0, sourceIdx * 6 + face, 0, 0, res, res);
+
+                mTexture->unbind();
+            }
+            mMipChain[i].flush();
+        }
+
+        gGL.popMatrix();
+        gGL.matrixMode(gGL.MM_MODELVIEW);
+        gGL.popMatrix();
+
+        gGL.getTexUnit(diffuseChannel)->unbind(LLTexUnit::TT_TEXTURE);
+        gReflectionMipProgram.unbind();
+    }
+
+    if (face == 5)
+    {
+        mMipChain[0].bindTarget();
+        static LLStaticHashedString sSourceIdx("sourceIdx");
+
+        {
+            //generate radiance map (even if this is not the irradiance map, we need the mip chain for the irradiance map)
+            gHeroRadianceGenProgram.bind();
+            mVertexBuffer->setBuffer();
+
+            S32 channel = gHeroRadianceGenProgram.enableTexture(LLShaderMgr::REFLECTION_PROBES, LLTexUnit::TT_CUBE_MAP_ARRAY);
+            mTexture->bind(channel);
+            gHeroRadianceGenProgram.uniform1i(sSourceIdx, sourceIdx);
+            gHeroRadianceGenProgram.uniform1f(LLShaderMgr::REFLECTION_PROBE_MAX_LOD, mMaxProbeLOD);
+            gHeroRadianceGenProgram.uniform1f(LLShaderMgr::REFLECTION_PROBE_STRENGTH, mHeroProbeStrength);
+            
+            U32 res = mMipChain[0].getWidth();
+
+            for (int i = 0; i < mMipChain.size(); ++i)
+            {
+                LL_PROFILE_GPU_ZONE("probe radiance gen");
+                static LLStaticHashedString sMipLevel("mipLevel");
+                static LLStaticHashedString sRoughness("roughness");
+                static LLStaticHashedString sWidth("u_width");
+                static LLStaticHashedString sStrength("probe_strength");
+
+                gHeroRadianceGenProgram.uniform1f(sRoughness, (F32) i / (F32) (mMipChain.size() - 1));
+                gHeroRadianceGenProgram.uniform1f(sMipLevel, i);
+                gHeroRadianceGenProgram.uniform1i(sWidth, mProbeResolution);
+                gHeroRadianceGenProgram.uniform1f(sStrength, 1);
+
+                for (int cf = 0; cf < 6; ++cf)
+                { // for each cube face
+                    LLCoordFrame frame;
+                    frame.lookAt(LLVector3(0, 0, 0), LLCubeMapArray::sClipToCubeLookVecs[cf], LLCubeMapArray::sClipToCubeUpVecs[cf]);
+
+                    F32 mat[16];
+                    frame.getOpenGLRotation(mat);
+                    gGL.loadMatrix(mat);
+
+                    mVertexBuffer->drawArrays(gGL.TRIANGLE_STRIP, 0, 4);
+
+                    glCopyTexSubImage3D(GL_TEXTURE_CUBE_MAP_ARRAY, i, 0, 0, probe->mCubeIndex * 6 + cf, 0, 0, res, res);
+                }
+
+                if (i != mMipChain.size() - 1)
+                {
+                    res /= 2;
+                    glViewport(0, 0, res, res);
+                }
+            }
+
+            gHeroRadianceGenProgram.unbind();
+        }
+
+        mMipChain[0].flush();
+    }
+}
+
+void LLHeroProbeManager::updateUniforms()
+{
+    if (!LLPipeline::sReflectionProbesEnabled)
+    {
+        return;
+    }
+
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
+    
+    struct HeroProbeData
+    {
+        LLVector4 heroPosition[1];
+        GLint heroProbeCount = 1;
+    };
+    
+    HeroProbeData hpd;
+    
+    LLMatrix4a modelview;
+    modelview.loadu(gGLModelView);
+    LLVector4a oa; // scratch space for transformed origin
+    oa.set(0, 0, 0, 0);
+    hpd.heroProbeCount = 1;
+    modelview.affineTransform(mProbes[0]->mOrigin, oa);
+    hpd.heroPosition[0].set(oa.getF32ptr());
+
+    //copy rpd into uniform buffer object
+    if (mUBO == 0)
+    {
+        glGenBuffers(1, &mUBO);
+    }
+
+    {
+        LL_PROFILE_ZONE_NAMED_CATEGORY_DISPLAY("rmmsu - update buffer");
+        glBindBuffer(GL_UNIFORM_BUFFER, mUBO);
+        glBufferData(GL_UNIFORM_BUFFER, sizeof(HeroProbeData), &hpd, GL_STREAM_DRAW);
+        glBindBuffer(GL_UNIFORM_BUFFER, 0);
+    }
+}
+
+void LLHeroProbeManager::setUniforms()
+{
+    if (!LLPipeline::sReflectionProbesEnabled)
+    {
+        return;
+    }
+
+    if (mUBO == 0)
+    { 
+        updateUniforms();
+    }
+    glBindBufferBase(GL_UNIFORM_BUFFER, 1, mUBO);
+}
+
+void LLHeroProbeManager::renderDebug()
+{
+    gDebugProgram.bind();
+
+    for (auto& probe : mProbes)
+    {
+        renderReflectionProbe(probe);
+    }
+
+    gDebugProgram.unbind();
+}
+
+void LLHeroProbeManager::initReflectionMaps()
+{
+    U32 count = LL_MAX_HERO_PROBE_COUNT;
+
+    if (mTexture.isNull() || mReflectionProbeCount != count || mReset)
+    {
+        mReset = false;
+        mReflectionProbeCount = count;
+        mProbeResolution      = gSavedSettings.getS32("RenderHeroProbeResolution");
+        mMaxProbeLOD = log2f(mProbeResolution) - 1.f; // number of mips - 1
+
+        mTexture = new LLCubeMapArray();
+
+        // store mReflectionProbeCount+2 cube maps, final two cube maps are used for render target and radiance map generation source)
+        mTexture->allocate(mProbeResolution, 3, mReflectionProbeCount + 2);
+
+        if (mDefaultProbe.isNull())
+        {
+            llassert(mProbes.empty()); // default probe MUST be the first probe created
+            mDefaultProbe = new LLReflectionMap();
+            mProbes.push_back(mDefaultProbe);
+        }
+
+        llassert(mProbes[0] == mDefaultProbe);
+
+        // For hero probes, we treat this as the main mirror probe.
+        
+        mDefaultProbe->mCubeIndex = 0;
+        mDefaultProbe->mCubeArray = mTexture;
+        mDefaultProbe->mDistance  = gSavedSettings.getF32("RenderHeroProbeDistance");
+        mDefaultProbe->mRadius = 4096.f;
+        mDefaultProbe->mProbeIndex = 0;
+        touch_default_probe(mDefaultProbe);
+        
+        mProbes.push_back(mDefaultProbe);
+    }
+
+    if (mVertexBuffer.isNull())
+    {
+        U32 mask = LLVertexBuffer::MAP_VERTEX;
+        LLPointer<LLVertexBuffer> buff = new LLVertexBuffer(mask);
+        buff->allocateBuffer(4, 0);
+
+        LLStrider<LLVector3> v;
+        
+        buff->getVertexStrider(v);
+        
+        v[0] = LLVector3(-1, -1, -1);
+        v[1] = LLVector3(1, -1, -1);
+        v[2] = LLVector3(-1, 1, -1);
+        v[3] = LLVector3(1, 1, -1);
+
+        buff->unmapBuffer();
+
+        mVertexBuffer = buff;
+    }
+}
+
+void LLHeroProbeManager::cleanup() 
+{ 
+    mVertexBuffer = nullptr;
+    mRenderTarget.release();
+    mHeroRenderTarget.release();
+
+    mMipChain.clear();
+
+    mTexture = nullptr;
+
+    mProbes.clear();
+
+    mReflectionMaps.clear();
+    
+    mDefaultProbe = nullptr;
+    mUpdatingProbe = nullptr;
+
+    glDeleteBuffers(1, &mUBO);
+    mUBO = 0;
+    
+    mHeroVOList.clear();
+    mNearestHero = nullptr;
+}
+
+void LLHeroProbeManager::doOcclusion()
+{
+    LLVector4a eye;
+    eye.load3(LLViewerCamera::instance().getOrigin().mV);
+
+    for (auto& probe : mProbes)
+    {
+        if (probe != nullptr && probe != mDefaultProbe)
+        {
+            probe->doOcclusion(eye);
+        }
+    }
+}
+
+void LLHeroProbeManager::registerViewerObject(LLVOVolume* drawablep)
+{
+    llassert(drawablep != nullptr);
+
+    if (mHeroVOList.find(drawablep) == mHeroVOList.end())
+    {
+        // Probe isn't in our list for consideration.  Add it.
+        mHeroVOList.insert(drawablep);
+    }
+}
+
+void LLHeroProbeManager::unregisterViewerObject(LLVOVolume* drawablep)
+{
+    if (mHeroVOList.find(drawablep) != mHeroVOList.end())
+    {
+        mHeroVOList.erase(drawablep);
+    }
+}
diff --git a/indra/newview/llheroprobemanager.h b/indra/newview/llheroprobemanager.h
new file mode 100644
index 0000000000..552c5dcaab
--- /dev/null
+++ b/indra/newview/llheroprobemanager.h
@@ -0,0 +1,141 @@
+/**
+ * @file llheroprobemanager.h
+ * @brief LLHeroProbeManager class declaration
+ *
+ * $LicenseInfo:firstyear=2022&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2022, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#pragma once
+
+#include "llreflectionmap.h"
+#include "llrendertarget.h"
+#include "llcubemaparray.h"
+#include "llcubemap.h"
+#include "lldrawable.h"
+
+class LLSpatialGroup;
+class LLViewerObject;
+
+// number of reflection probes to keep in vram
+#define LL_MAX_HERO_PROBE_COUNT 2
+
+class alignas(16) LLHeroProbeManager
+{
+    LL_ALIGN_NEW
+public:
+    enum class DetailLevel 
+    {
+        STATIC_ONLY = 0,
+        STATIC_AND_DYNAMIC,
+        REALTIME = 2
+    };
+
+    // allocate an environment map of the given resolution 
+    LLHeroProbeManager();
+
+    // release any GL state 
+    void cleanup();
+
+    // maintain reflection probes
+    void update();
+
+    // debug display, called from llspatialpartition if reflection
+    // probe debug display is active
+    void renderDebug();
+
+    // call once at startup to allocate cubemap arrays
+    void initReflectionMaps();
+
+    // perform occlusion culling on all active reflection probes
+    void doOcclusion();
+
+    void registerViewerObject(LLVOVolume *drawablep);
+    void unregisterViewerObject(LLVOVolume* drawablep);
+
+    bool isMirrorPass() const { return mRenderingMirror; }
+
+    LLVector3 mMirrorPosition;
+    LLVector3 mMirrorNormal;
+    
+private:
+    friend class LLPipeline;
+    
+    // update UBO used for rendering (call only once per render pipe flush)
+    void updateUniforms();
+
+    // bind UBO used for rendering
+    void setUniforms();
+
+    // render target for cube snapshots
+    // used to generate mipmaps without doing a copy-to-texture
+    LLRenderTarget mRenderTarget;
+    
+    LLRenderTarget mHeroRenderTarget;
+
+    std::vector<LLRenderTarget> mMipChain;
+
+    // storage for reflection probe radiance maps (plus two scratch space cubemaps)
+    LLPointer<LLCubeMapArray> mTexture;
+
+    // vertex buffer for pushing verts to filter shaders
+    LLPointer<LLVertexBuffer> mVertexBuffer;
+
+    LLPlane mCurrentClipPlane;
+
+
+    // update the specified face of the specified probe
+    void updateProbeFace(LLReflectionMap* probe, U32 face, F32 near_clip);
+    
+    // list of active reflection maps
+    std::vector<LLPointer<LLReflectionMap> > mProbes;
+
+    // handle to UBO
+    U32 mUBO = 0;
+
+    // list of maps being used for rendering
+    std::vector<LLReflectionMap*> mReflectionMaps;
+
+    LLReflectionMap* mUpdatingProbe = nullptr;
+
+    LLPointer<LLReflectionMap> mDefaultProbe;  // default reflection probe to fall back to for pixels with no probe influences (should always be at cube index 0)
+
+    // number of reflection probes to use for rendering
+    U32 mReflectionProbeCount;
+
+    // resolution of reflection probes
+    U32 mProbeResolution = 1024;
+    
+    // maximum LoD of reflection probes (mip levels - 1)
+    F32 mMaxProbeLOD = 6.f;
+    
+    F32 mHeroProbeStrength = 1.f;
+    bool mIsInTransition = false;
+
+    // if true, reset all probe render state on the next update (for teleports and sky changes)
+    bool mReset = false;
+
+    bool mRenderingMirror = false;
+    
+    std::set<LLPointer<LLVOVolume>>               mHeroVOList;
+    LLPointer<LLVOVolume>                         mNearestHero;
+};
+
diff --git a/indra/newview/llmaterialeditor.cpp b/indra/newview/llmaterialeditor.cpp
index b7828db3a9..f939418893 100644
--- a/indra/newview/llmaterialeditor.cpp
+++ b/indra/newview/llmaterialeditor.cpp
@@ -1870,7 +1870,7 @@ static void pack_textures(
     if (normal_img)
     {
         // create a losslessly compressed version of the normal map
-        normal_j2c = LLViewerTextureList::convertToUploadFile(normal_img, 1024, false, true);
+        normal_j2c = LLViewerTextureList::convertToUploadFile(normal_img, 2048, false, true);
         LL_DEBUGS("MaterialEditor") << "Normal: " << normal_j2c->getDataSize() << LL_ENDL;
     }
 
diff --git a/indra/newview/llpanelface.cpp b/indra/newview/llpanelface.cpp
index a527ebe47f..4f3b233218 100644
--- a/indra/newview/llpanelface.cpp
+++ b/indra/newview/llpanelface.cpp
@@ -1793,6 +1793,7 @@ void LLPanelFace::updateUI(bool force_set_values /*false*/)
 					getChild<LLUICtrl>("shinyOffsetV")->setValue(offset_y);
 					getChild<LLUICtrl>("glossiness")->setValue(material->getSpecularLightExponent());
 					getChild<LLUICtrl>("environment")->setValue(material->getEnvironmentIntensity());
+                    getChild<LLUICtrl>("mirror")->setValue(material->getEnvironmentIntensity());
 
 					updateShinyControls(!material->getSpecularID().isNull(), true);
 				}
diff --git a/indra/newview/llpanelface.h b/indra/newview/llpanelface.h
index a64b85815f..05860b995f 100644
--- a/indra/newview/llpanelface.h
+++ b/indra/newview/llpanelface.h
@@ -145,6 +145,7 @@ protected:
 	void			sendTexGen();				// applies and sends bump map
 	void			sendShiny(U32 shininess);			// applies and sends shininess
 	void			sendFullbright();		// applies and sends full bright
+
 	void			sendGlow();
     void            alignTestureLayer();
 
@@ -234,7 +235,7 @@ protected:
 	static void		onCommitShiny(				LLUICtrl* ctrl, void* userdata);
 	static void		onCommitAlphaMode(		LLUICtrl* ctrl, void* userdata);
 	static void		onCommitFullbright(		LLUICtrl* ctrl, void* userdata);
-	static void    onCommitGlow(				LLUICtrl* ctrl, void *userdata);
+	static void     onCommitGlow(				LLUICtrl* ctrl, void *userdata);
 	static void		onCommitPlanarAlign(		LLUICtrl* ctrl, void* userdata);
 	static void		onCommitRepeatsPerMeter(	LLUICtrl* ctrl, void* userinfo);
 
diff --git a/indra/newview/llpanelvolume.cpp b/indra/newview/llpanelvolume.cpp
index 595609b4de..8d8263448d 100644
--- a/indra/newview/llpanelvolume.cpp
+++ b/indra/newview/llpanelvolume.cpp
@@ -150,7 +150,7 @@ BOOL	LLPanelVolume::postBuild()
     // REFLECTION PROBE Parameters
     {
         childSetCommitCallback("Reflection Probe", onCommitIsReflectionProbe, this);
-        childSetCommitCallback("Probe Dynamic", onCommitProbe, this);
+        childSetCommitCallback("Probe Update Type", onCommitProbe, this);
         childSetCommitCallback("Probe Volume Type", onCommitProbe, this);
         childSetCommitCallback("Probe Ambiance", onCommitProbe, this);
         childSetCommitCallback("Probe Near Clip", onCommitProbe, this);
@@ -304,7 +304,7 @@ void LLPanelVolume::getState( )
 		getChildView("select_single")->setVisible(true);
 		getChildView("select_single")->setEnabled(true);
 	}
-	
+    
 	// Light properties
 	BOOL is_light = volobjp && volobjp->getIsLight();
 	getChild<LLUICtrl>("Light Checkbox Ctrl")->setValue(is_light);
@@ -392,17 +392,25 @@ void LLPanelVolume::getState( )
 
     bool probe_enabled = is_probe && editable && single_volume;
 
+    bool mirrors_enabled = LLPipeline::RenderMirrors;
+
+	getChildView("Probe Update Type")->setVisible(mirrors_enabled);
+    getChildView("Probe Update Label")->setVisible(mirrors_enabled);
+    getChildView("Probe Dynamic")->setVisible(!mirrors_enabled);
+
     getChildView("Probe Dynamic")->setEnabled(probe_enabled);
+    getChildView("Probe Update Type")->setEnabled(probe_enabled);
     getChildView("Probe Volume Type")->setEnabled(probe_enabled);
     getChildView("Probe Ambiance")->setEnabled(probe_enabled);
     getChildView("Probe Near Clip")->setEnabled(probe_enabled);
+    getChildView("Probe Update Label")->setEnabled(probe_enabled);
 
     if (!probe_enabled)
     {
         getChild<LLComboBox>("Probe Volume Type", true)->clear();
         getChild<LLSpinCtrl>("Probe Ambiance", true)->clear();
         getChild<LLSpinCtrl>("Probe Near Clip", true)->clear();
-        getChild<LLCheckBoxCtrl>("Probe Dynamic", true)->clear();
+        getChild<LLComboBox>("Probe Update Type", true)->clear();
     }
     else
     {
@@ -416,10 +424,28 @@ void LLPanelVolume::getState( )
             volume_type = "Sphere";
         }
 
+		std::string update_type;
+        if (volobjp->getReflectionProbeIsDynamic())
+        {
+            update_type = "Dynamic";
+        }
+        else if (volobjp->getReflectionProbeIsMirror())
+        {
+            update_type = "Mirror";
+
+        }
+        else
+        {
+            update_type = "Static";
+		}
+
+        getChildView("Probe Ambiance")->setEnabled(update_type != "Mirror");
+        getChildView("Probe Near Clip")->setEnabled(update_type != "Mirror");
+
         getChild<LLComboBox>("Probe Volume Type", true)->setValue(volume_type);
         getChild<LLSpinCtrl>("Probe Ambiance", true)->setValue(volobjp->getReflectionProbeAmbiance());
         getChild<LLSpinCtrl>("Probe Near Clip", true)->setValue(volobjp->getReflectionProbeNearClip());
-        getChild<LLCheckBoxCtrl>("Probe Dynamic", true)->setValue(volobjp->getReflectionProbeIsDynamic());
+        getChild<LLComboBox>("Probe Update Type", true)->setValue(update_type);
     }
 
     // Animated Mesh
@@ -706,7 +732,7 @@ void LLPanelVolume::clearCtrls()
 
     getChildView("Reflection Probe")->setEnabled(false);;
     getChildView("Probe Volume Type")->setEnabled(false);
-    getChildView("Probe Dynamic")->setEnabled(false);
+    getChildView("Probe Update Type")->setEnabled(false);
     getChildView("Probe Ambiance")->setEnabled(false);
     getChildView("Probe Near Clip")->setEnabled(false);
     getChildView("Animated Mesh Checkbox Ctrl")->setEnabled(false);
@@ -1399,7 +1425,14 @@ void LLPanelVolume::onCommitProbe(LLUICtrl* ctrl, void* userdata)
 
     volobjp->setReflectionProbeAmbiance((F32)self->getChild<LLUICtrl>("Probe Ambiance")->getValue().asReal());
     volobjp->setReflectionProbeNearClip((F32)self->getChild<LLUICtrl>("Probe Near Clip")->getValue().asReal());
-    volobjp->setReflectionProbeIsDynamic(self->getChild<LLUICtrl>("Probe Dynamic")->getValue().asBoolean());
+
+    std::string update_type = self->getChild<LLUICtrl>("Probe Update Type")->getValue().asString();
+
+	volobjp->setReflectionProbeIsDynamic(update_type == "Dynamic");
+    volobjp->setReflectionProbeIsMirror(update_type == "Mirror");
+
+    self->getChildView("Probe Ambiance")->setEnabled(update_type != "Mirror");
+    self->getChildView("Probe Near Clip")->setEnabled(update_type != "Mirror");
 
     std::string shape_type = self->getChild<LLUICtrl>("Probe Volume Type")->getValue().asString();
 
diff --git a/indra/newview/llpanelvolume.h b/indra/newview/llpanelvolume.h
index 01b7ebb75c..aafefa918f 100644
--- a/indra/newview/llpanelvolume.h
+++ b/indra/newview/llpanelvolume.h
@@ -57,7 +57,7 @@ public:
 	void			refresh();
 
 	void			sendIsLight();
-    
+
     // when an object is becoming a refleciton probe, present a dialog asking for confirmation
     // otherwise, send the reflection probe update immediately
     void            sendIsReflectionProbe();
diff --git a/indra/newview/llreflectionmap.cpp b/indra/newview/llreflectionmap.cpp
index a26445b4bc..6d5797395c 100644
--- a/indra/newview/llreflectionmap.cpp
+++ b/indra/newview/llreflectionmap.cpp
@@ -49,7 +49,7 @@ LLReflectionMap::~LLReflectionMap()
     }
 }
 
-void LLReflectionMap::update(U32 resolution, U32 face)
+void LLReflectionMap::update(U32 resolution, U32 face, bool force_dynamic, F32 near_clip, bool useClipPlane, LLPlane clipPlane)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
     mLastUpdateTime = gFrameTimeSeconds;
@@ -63,7 +63,10 @@ void LLReflectionMap::update(U32 resolution, U32 face)
     {
         resolution /= 2;
     }
-    gViewerWindow->cubeSnapshot(LLVector3(mOrigin), mCubeArray, mCubeIndex, face, getNearClip(), getIsDynamic());
+
+    F32 clip = (near_clip > 0) ? near_clip : getNearClip();
+    
+    gViewerWindow->cubeSnapshot(LLVector3(mOrigin), mCubeArray, mCubeIndex, face, clip, getIsDynamic() || force_dynamic, useClipPlane, clipPlane);
 }
 
 void LLReflectionMap::autoAdjustOrigin()
diff --git a/indra/newview/llreflectionmap.h b/indra/newview/llreflectionmap.h
index 7ea0fe6187..9e888f20d0 100644
--- a/indra/newview/llreflectionmap.h
+++ b/indra/newview/llreflectionmap.h
@@ -36,6 +36,15 @@ class alignas(16) LLReflectionMap : public LLRefCount
 {
     LL_ALIGN_NEW
 public:
+    
+    enum class ProbeType
+    {
+        ALL = 0,
+        RADIANCE,
+        IRRADIANCE,
+        REFLECTION
+    };
+    
     // allocate an environment map of the given resolution 
     LLReflectionMap();
 
@@ -43,7 +52,7 @@ public:
 
     // update this environment map
     // resolution - size of cube map to generate
-    void update(U32 resolution, U32 face);
+    void update(U32 resolution, U32 face, bool force_dynamic = false, F32 near_clip = -1.f, bool useClipPlane = false, LLPlane clipPlane = LLPlane(LLVector3(0, 0, 0), LLVector3(0, 0, 1)));
 
     // for volume partition probes, try to place this probe in the best spot
     void autoAdjustOrigin();
@@ -127,5 +136,7 @@ public:
     GLuint mOcclusionQuery = 0;
     bool mOccluded = false;
     U32 mOcclusionPendingFrames = 0;
+    
+    ProbeType mType;
 };
 
diff --git a/indra/newview/llreflectionmapmanager.cpp b/indra/newview/llreflectionmapmanager.cpp
index 69674417c1..8506886409 100644
--- a/indra/newview/llreflectionmapmanager.cpp
+++ b/indra/newview/llreflectionmapmanager.cpp
@@ -27,6 +27,9 @@
 #include "llviewerprecompiledheaders.h"
 
 #include "llreflectionmapmanager.h"
+
+#include <vector>
+
 #include "llviewercamera.h"
 #include "llspatialpartition.h"
 #include "llviewerregion.h"
@@ -306,8 +309,8 @@ void LLReflectionMapManager::update()
             }
         }
 
-        if (realtime && 
-            closestDynamic == nullptr && 
+        if (realtime &&
+            closestDynamic == nullptr &&
             probe->mCubeIndex != -1 &&
             probe->getIsDynamic())
         {
@@ -322,7 +325,7 @@ void LLReflectionMapManager::update()
         // should do a full irradiance pass on "odd" frames and a radiance pass on "even" frames
         closestDynamic->autoAdjustOrigin();
 
-        // store and override the value of "isRadiancePass" -- parts of the render pipe rely on "isRadiancePass" to set 
+        // store and override the value of "isRadiancePass" -- parts of the render pipe rely on "isRadiancePass" to set
         // lighting values etc
         bool radiance_pass = isRadiancePass();
         mRadiancePass = mRealtimeRadiancePass;
@@ -573,7 +576,7 @@ void LLReflectionMapManager::doProbeUpdate()
 
 // Do the reflection map update render passes.
 // For every 12 calls of this function, one complete reflection probe radiance map and irradiance map is generated
-// First six passes render the scene with direct lighting only into a scratch space cube map at the end of the cube map array and generate 
+// First six passes render the scene with direct lighting only into a scratch space cube map at the end of the cube map array and generate
 // a simple mip chain (not convolution filter).
 // At the end of these passes, an irradiance map is generated for this probe and placed into the irradiance cube map array at the index for this probe
 // The next six passes render the scene with both radiance and irradiance into the same scratch space cube map and generate a simple mip chain.
@@ -734,6 +737,7 @@ void LLReflectionMapManager::updateProbeFace(LLReflectionMap* probe, U32 face)
             mTexture->bind(channel);
             gRadianceGenProgram.uniform1i(sSourceIdx, sourceIdx);
             gRadianceGenProgram.uniform1f(LLShaderMgr::REFLECTION_PROBE_MAX_LOD, mMaxProbeLOD);
+            gRadianceGenProgram.uniform1f(LLShaderMgr::REFLECTION_PROBE_STRENGTH, 1.f);
 
             U32 res = mMipChain[0].getWidth();
 
@@ -898,14 +902,14 @@ void LLReflectionMapManager::updateUniforms()
     // see class3/deferred/reflectionProbeF.glsl
     struct ReflectionProbeData
     {
-        // for box probes, matrix that transforms from camera space to a [-1, 1] cube representing the bounding box of 
+        // for box probes, matrix that transforms from camera space to a [-1, 1] cube representing the bounding box of
         // the box probe
-        LLMatrix4 refBox[LL_MAX_REFLECTION_PROBE_COUNT]; 
+        LLMatrix4 refBox[LL_MAX_REFLECTION_PROBE_COUNT];
 
         // for sphere probes, origin (xyz) and radius (w) of refmaps in clip space
-        LLVector4 refSphere[LL_MAX_REFLECTION_PROBE_COUNT]; 
+        LLVector4 refSphere[LL_MAX_REFLECTION_PROBE_COUNT];
 
-        // extra parameters 
+        // extra parameters
         //  x - irradiance scale
         //  y - radiance scale
         //  z - fade in
@@ -917,14 +921,14 @@ void LLReflectionMapManager::updateUniforms()
         //  [i][1] - index into "refNeighbor" for probes that intersect this probe
         //  [i][2] - number of probes  that intersect this probe, or -1 for no neighbors
         //  [i][3] - priority (probe type stored in sign bit - positive for spheres, negative for boxes)
-        GLint refIndex[LL_MAX_REFLECTION_PROBE_COUNT][4]; 
+        GLint refIndex[LL_MAX_REFLECTION_PROBE_COUNT][4];
 
         // list of neighbor indices
-        GLint refNeighbor[4096]; 
+        GLint refNeighbor[4096];
 
         GLint refBucket[256][4]; //lookup table for which index to start with for the given Z depth
         // numbrer of active refmaps
-        GLint refmapCount;  
+        GLint refmapCount;
     };
 
     mReflectionMaps.resize(mReflectionProbeCount);
@@ -1152,7 +1156,7 @@ void LLReflectionMapManager::setUniforms()
     }
 
     if (mUBO == 0)
-    { 
+    {
         updateUniforms();
     }
     glBindBufferBase(GL_UNIFORM_BUFFER, 1, mUBO);
@@ -1343,8 +1347,8 @@ void LLReflectionMapManager::initReflectionMaps()
     }
 }
 
-void LLReflectionMapManager::cleanup() 
-{ 
+void LLReflectionMapManager::cleanup()
+{
     mVertexBuffer = nullptr;
     mRenderTarget.release();
 
@@ -1383,3 +1387,39 @@ void LLReflectionMapManager::doOcclusion()
         }
     }
 }
+
+void LLReflectionMapManager::forceDefaultProbeAndUpdateUniforms(bool force)
+{
+    static std::vector<bool> mProbeWasOccluded;
+
+    if (force)
+    {
+        llassert(mProbeWasOccluded.empty());
+
+        for (size_t i = 0; i < mProbes.size(); ++i)
+        {
+            auto& probe = mProbes[i];
+            mProbeWasOccluded.push_back(probe->mOccluded);
+            if (probe != nullptr && probe != mDefaultProbe)
+            {
+                probe->mOccluded = true;
+            }
+        }
+
+        updateUniforms();
+    }
+    else
+    {
+        llassert(mProbes.size() == mProbeWasOccluded.size());
+
+        const size_t n = llmin(mProbes.size(), mProbeWasOccluded.size());
+        for (size_t i = 0; i < n; ++i)
+        {
+            auto& probe = mProbes[i];
+            llassert(probe->mOccluded == (probe != mDefaultProbe));
+            probe->mOccluded = mProbeWasOccluded[i];
+        }
+        mProbeWasOccluded.clear();
+        mProbeWasOccluded.shrink_to_fit();
+    }
+}
diff --git a/indra/newview/llreflectionmapmanager.h b/indra/newview/llreflectionmapmanager.h
index b77a33da89..0fee99eefc 100644
--- a/indra/newview/llreflectionmapmanager.h
+++ b/indra/newview/llreflectionmapmanager.h
@@ -43,21 +43,23 @@ class LLViewerObject;
 // reflection probe mininum scale
 #define LL_REFLECTION_PROBE_MINIMUM_SCALE 1.f;
 
+void renderReflectionProbe(LLReflectionMap* probe);
+
 class alignas(16) LLReflectionMapManager
 {
     LL_ALIGN_NEW
 public:
-    enum class DetailLevel 
+    enum class DetailLevel
     {
         STATIC_ONLY = 0,
         STATIC_AND_DYNAMIC,
         REALTIME = 2
     };
 
-    // allocate an environment map of the given resolution 
+    // allocate an environment map of the given resolution
     LLReflectionMapManager();
 
-    // release any GL state 
+    // release any GL state
     void cleanup();
 
     // maintain reflection probes
@@ -106,8 +108,14 @@ public:
     // perform occlusion culling on all active reflection probes
     void doOcclusion();
 
+    // *HACK: "cull" all reflection probes except the default one. Only call
+    // this if you don't intend to call updateUniforms directly. Call again
+    // with false when done.
+    void forceDefaultProbeAndUpdateUniforms(bool force = true);
+
 private:
     friend class LLPipeline;
+    friend class LLHeroProbeManager;
 
     // initialize mCubeFree array to default values
     void initCubeFree();
@@ -119,7 +127,7 @@ private:
     // returns -1 if allocation failed
     S32 allocateCubeIndex();
 
-    // update the neighbors of the given probe 
+    // update the neighbors of the given probe
     void updateNeighbors(LLReflectionMap* probe);
 
     // update UBO used for rendering (call only once per render pipe flush)
diff --git a/indra/newview/llsettingsvo.cpp b/indra/newview/llsettingsvo.cpp
index c07c939862..afae5f140b 100644
--- a/indra/newview/llsettingsvo.cpp
+++ b/indra/newview/llsettingsvo.cpp
@@ -718,11 +718,11 @@ void LLSettingsVOSky::applySpecial(void *ptarget, bool force)
     LLSettingsSky::ptr_t psky = LLEnvironment::instance().getCurrentSky();
 
     // TODO -- make these getters return vec3s
-    LLVector3 sunDiffuse = LLVector3(psky->getSunlightColor().mV);
-    LLVector3 moonDiffuse = LLVector3(psky->getMoonlightColor().mV);
+    LLVector3 sun_light_color = LLVector3(psky->getSunlightColor().mV);
+    LLVector3 moon_light_color = LLVector3(psky->getMoonlightColor().mV);
 
-    shader->uniform3fv(LLShaderMgr::SUNLIGHT_COLOR, sunDiffuse);
-    shader->uniform3fv(LLShaderMgr::MOONLIGHT_COLOR, moonDiffuse);
+    shader->uniform3fv(LLShaderMgr::SUNLIGHT_COLOR, sun_light_color);
+    shader->uniform3fv(LLShaderMgr::MOONLIGHT_COLOR, moon_light_color);
 
     shader->uniform3fv(LLShaderMgr::CLOUD_COLOR, LLVector3(psky->getCloudColor().mV));
 
@@ -765,9 +765,9 @@ void LLSettingsVOSky::applySpecial(void *ptarget, bool force)
             shader->uniform1f(LLShaderMgr::SKY_HDR_SCALE, auto_adjust_hdr_scale);
             LLColor3 blue_horizon = getBlueHorizon() * auto_adjust_blue_horizon_scale;
             LLColor3 blue_density = getBlueDensity() * auto_adjust_blue_density_scale;
-            LLColor3 sun_diffuse = getSunDiffuse() * auto_adjust_sun_color_scale;
+            sun_light_color = sun_light_color * auto_adjust_sun_color_scale;
             
-            shader->uniform3fv(LLShaderMgr::SUNLIGHT_COLOR, sun_diffuse.mV);
+            shader->uniform3fv(LLShaderMgr::SUNLIGHT_COLOR, sun_light_color.mV);
             shader->uniform3fv(LLShaderMgr::BLUE_DENSITY, blue_density.mV);
             shader->uniform3fv(LLShaderMgr::BLUE_HORIZON, blue_horizon.mV);
 
@@ -1009,6 +1009,7 @@ void LLSettingsVOWater::applySpecial(void *ptarget, bool force)
 
         glh::matrix4f mat(modelView);
         glh::matrix4f invtrans = mat.inverse().transpose();
+        invtrans.m[3] = invtrans.m[7] = invtrans.m[11] = 0.f;
         glh::vec3f enorm;
         glh::vec3f ep;
         invtrans.mult_matrix_vec(norm, enorm);
@@ -1017,12 +1018,29 @@ void LLSettingsVOWater::applySpecial(void *ptarget, bool force)
 
         LLVector4 waterPlane(enorm.v[0], enorm.v[1], enorm.v[2], -ep.dot(enorm));
 
+        norm = glh::vec3f(gPipeline.mHeroProbeManager.mMirrorNormal.mV);
+        p    = glh::vec3f(gPipeline.mHeroProbeManager.mMirrorPosition.mV);
+        invtrans.mult_matrix_vec(norm, enorm);
+        enorm.normalize();
+        mat.mult_matrix_vec(p, ep);
+
+        LLVector4 mirrorPlane(enorm.v[0], enorm.v[1], enorm.v[2], -ep.dot(enorm));
+
         LLDrawPoolAlpha::sWaterPlane = waterPlane;
 
         shader->uniform4fv(LLShaderMgr::WATER_WATERPLANE, waterPlane.mV);
-
+        shader->uniform4fv(LLShaderMgr::CLIP_PLANE, mirrorPlane.mV);
         LLVector4 light_direction = env.getClampedLightNorm();
 
+        if (gPipeline.mHeroProbeManager.isMirrorPass())
+        {
+            shader->uniform1f(LLShaderMgr::MIRROR_FLAG, 1);
+        }
+        else
+        {
+            shader->uniform1f(LLShaderMgr::MIRROR_FLAG, 0);
+        }
+
         F32 waterFogKS = 1.f / llmax(light_direction.mV[2], WATER_FOG_LIGHT_CLAMP);
 
         shader->uniform1f(LLShaderMgr::WATER_FOGKS, waterFogKS);
diff --git a/indra/newview/llspatialpartition.cpp b/indra/newview/llspatialpartition.cpp
index 931880a475..40e8e526d1 100644
--- a/indra/newview/llspatialpartition.cpp
+++ b/indra/newview/llspatialpartition.cpp
@@ -47,6 +47,7 @@
 #include "pipeline.h"
 #include "llmeshrepository.h"
 #include "llrender.h"
+#include "lldrawpool.h"
 #include "lloctree.h"
 #include "llphysicsshapebuilderutil.h"
 #include "llvoavatar.h"
@@ -2000,7 +2001,11 @@ void renderBoundingBox(LLDrawable* drawable, BOOL set_color = TRUE)
 		drawBoxOutline(pos,size);
 	}
 }
-
+// *TODO: LLDrawables which are not part of LLVOVolumes fall into a different
+// code path which uses a shader - it was tested to be faster than mapping a
+// vertex buffer in the terrain case. Consider using it for LLVOVolumes as well
+// to simplify and speed up this debug code. Alternatively, a compute shader is
+// likely faster. -Cosmic,2023-09-28
 void renderNormals(LLDrawable *drawablep)
 {
     if (!drawablep->isVisible())
@@ -2008,11 +2013,13 @@ void renderNormals(LLDrawable *drawablep)
 
     LLVertexBuffer::unbind();
 
+	LLViewerObject* obj = drawablep->getVObj();
     LLVOVolume *vol = drawablep->getVOVolume();
 
-    if (vol)
+	if (obj)
     {
-        LLVolume *volume = vol->getVolume();
+		LLGLEnable blend(GL_BLEND);
+        LLGLDepthTest gl_depth(GL_TRUE, GL_FALSE);
 
         // Drawable's normals & tangents are stored in model space, i.e. before any scaling is applied.
         //
@@ -2021,68 +2028,136 @@ void renderNormals(LLDrawable *drawablep)
         // transform. We get that effect here by pre-applying the inverse scale (twice, because
         // one forward scale will be re-applied via the MVP in the vertex shader)
 
-        LLVector3  scale_v3 = vol->getScale();
-        float      scale_len = scale_v3.length();
-        LLVector4a obj_scale(scale_v3.mV[VX], scale_v3.mV[VY], scale_v3.mV[VZ]);
-        obj_scale.normalize3();
+        LLVector4a inv_scale;
+		float scale_len;
+        if (vol)
+        {
+            LLVector3  scale_v3 = vol->getScale();
+            LLVector4a obj_scale(scale_v3.mV[VX], scale_v3.mV[VY], scale_v3.mV[VZ]);
+            obj_scale.normalize3();
 
-        // Normals &tangent line segments get scaled along with the object. Divide by scale length
-        // to keep the as-viewed lengths (relatively) constant with the debug setting length
-        float draw_length = gSavedSettings.getF32("RenderDebugNormalScale") / scale_len;
+            // Create inverse-scale vector for normals
+            inv_scale.set(1.0 / scale_v3.mV[VX], 1.0 / scale_v3.mV[VY], 1.0 / scale_v3.mV[VZ], 0.0);
+            inv_scale.mul(inv_scale);  // Squared, to apply inverse scale twice
 
-        // Create inverse-scale vector for normals
-        LLVector4a inv_scale(1.0 / scale_v3.mV[VX], 1.0 / scale_v3.mV[VY], 1.0 / scale_v3.mV[VZ]);
-        inv_scale.mul(inv_scale);  // Squared, to apply inverse scale twice
-        inv_scale.normalize3fast();
+            inv_scale.normalize3fast();
+			scale_len = scale_v3.length();
+        }
+        else
+        {
+			inv_scale.set(1.0, 1.0, 1.0, 0.0);
+			scale_len = 1.0;
+        }
 
         gGL.pushMatrix();
-        gGL.multMatrix((F32 *) vol->getRelativeXform().mMatrix);
+        if (vol)
+        {
+            gGL.multMatrix((F32 *) vol->getRelativeXform().mMatrix);
+        }
 
         gGL.getTexUnit(0)->unbind(LLTexUnit::TT_TEXTURE);
 
-        for (S32 i = 0; i < volume->getNumVolumeFaces(); ++i)
+        // Normals &tangent line segments get scaled along with the object. Divide by scale length
+        // to keep the as-viewed lengths (relatively) constant with the debug setting length
+        float draw_length = gSavedSettings.getF32("RenderDebugNormalScale") / scale_len;
+
+        std::vector<LLVolumeFace>* faces = nullptr;
+		std::vector<LLFace*>* drawable_faces = nullptr;
+        if (vol)
+        {
+            LLVolume* volume = vol->getVolume();
+            faces = &volume->getVolumeFaces();
+        }
+        else
         {
-            const LLVolumeFace &face = volume->getVolumeFace(i);
+			drawable_faces = &drawablep->getFaces();
+        }
 
-            gGL.flush();
-            gGL.diffuseColor4f(1, 1, 0, 1);
-            gGL.begin(LLRender::LINES);
-            for (S32 j = 0; j < face.mNumVertices; ++j)
-            {
-                LLVector4a n, p;
+		if (faces)
+		{
+			for (auto it = faces->begin(); it != faces->end(); ++it)
+			{
+				const LLVolumeFace& face = *it;
+
+				gGL.flush();
+				gGL.diffuseColor4f(1, 1, 0, 1);
+				gGL.begin(LLRender::LINES);
+				for (S32 j = 0; j < face.mNumVertices; ++j)
+				{
+					LLVector4a n, p;
 
-                n.setMul(face.mNormals[j], 1.0);
-                n.mul(inv_scale);  // Pre-scale normal, so it's left with an inverse-transpose xform after MVP
-                n.normalize3fast();
-                n.mul(draw_length);
-                p.setAdd(face.mPositions[j], n);
+					n.setMul(face.mNormals[j], 1.0);
+					n.mul(inv_scale);  // Pre-scale normal, so it's left with an inverse-transpose xform after MVP
+					n.normalize3fast();
+					n.mul(draw_length);
+					p.setAdd(face.mPositions[j], n);
 
-                gGL.vertex3fv(face.mPositions[j].getF32ptr());
-                gGL.vertex3fv(p.getF32ptr());
-            }
-            gGL.end();
+					gGL.vertex3fv(face.mPositions[j].getF32ptr());
+					gGL.vertex3fv(p.getF32ptr());
+				}
+				gGL.end();
+
+				// Tangents are simple vectors and do not require reorientation via pre-scaling
+				if (face.mTangents)
+				{
+					gGL.flush();
+					gGL.diffuseColor4f(0, 1, 1, 1);
+					gGL.begin(LLRender::LINES);
+					for (S32 j = 0; j < face.mNumVertices; ++j)
+					{
+						LLVector4a t, p;
 
-            // Tangents are simple vectors and do not require reorientation via pre-scaling
-            if (face.mTangents)
+						t.setMul(face.mTangents[j], 1.0f);
+						t.normalize3fast();
+						t.mul(draw_length);
+						p.setAdd(face.mPositions[j], t);
+
+						gGL.vertex3fv(face.mPositions[j].getF32ptr());
+						gGL.vertex3fv(p.getF32ptr());
+					}
+					gGL.end();
+				}
+			}
+		}
+		else if (drawable_faces)
+		{
+			// *HACK: Prepare to restore previous shader as other debug code depends on a simpler shader being present
+			llassert(LLGLSLShader::sCurBoundShaderPtr == &gDebugProgram);
+			LLGLSLShader* prev_shader = LLGLSLShader::sCurBoundShaderPtr;
+            for (auto it = drawable_faces->begin(); it != drawable_faces->end(); ++it)
             {
-                gGL.flush();
-                gGL.diffuseColor4f(0, 1, 1, 1);
-                gGL.begin(LLRender::LINES);
-                for (S32 j = 0; j < face.mNumVertices; ++j)
+                LLFace* facep = *it;
+                LLFace& face = **it;
+                LLVertexBuffer* buf = face.getVertexBuffer();
+                if (!buf) { continue; }
+				U32 mask_vn = LLVertexBuffer::TYPE_VERTEX | LLVertexBuffer::TYPE_NORMAL;
+                if ((buf->getTypeMask() & mask_vn) != mask_vn) { continue; }
+
+                LLGLSLShader* shader;
+                if ((buf->getTypeMask() & LLVertexBuffer::TYPE_TANGENT) != LLVertexBuffer::TYPE_TANGENT)
                 {
-                    LLVector4a t, p;
+                    shader = &gNormalDebugProgram[NORMAL_DEBUG_SHADER_DEFAULT];
+                }
+                else
+                {
+                    shader = &gNormalDebugProgram[NORMAL_DEBUG_SHADER_WITH_TANGENTS];
+                }
+                shader->bind();
 
-                    t.setMul(face.mTangents[j], 1.0f);
-                    t.normalize3fast();
-                    t.mul(draw_length);
-                    p.setAdd(face.mPositions[j], t);
+                shader->uniform1f(LLShaderMgr::DEBUG_NORMAL_DRAW_LENGTH, draw_length);
 
-                    gGL.vertex3fv(face.mPositions[j].getF32ptr());
-                    gGL.vertex3fv(p.getF32ptr());
-                }
-                gGL.end();
+                LLRenderPass::applyModelMatrix(&facep->getDrawable()->getRegion()->mRenderMatrix);
+
+                buf->setBuffer();
+                // *NOTE: The render type in the vertex shader is TRIANGLES, but gets converted to LINES in the geometry shader
+                // *NOTE: For terrain normal debug, this seems to also include vertices for water, which is technically not part of the terrain. Should fix that at some point.
+                buf->drawRange(LLRender::TRIANGLES, face.getGeomIndex(), face.getGeomIndex() + face.getGeomCount()-1, face.getIndicesCount(), face.getIndicesStart());
             }
-        }
+			if (prev_shader)
+			{
+				prev_shader->bind();
+			}
+		}
 
         gGL.popMatrix();
     }
diff --git a/indra/newview/llsurface.cpp b/indra/newview/llsurface.cpp
index 1418499f8b..804afe6266 100644
--- a/indra/newview/llsurface.cpp
+++ b/indra/newview/llsurface.cpp
@@ -643,17 +643,18 @@ void LLSurface::updatePatchVisibilities(LLAgent &agent)
 	}
 }
 
-BOOL LLSurface::idleUpdate(F32 max_update_time)
+template<bool PBR>
+bool LLSurface::idleUpdate(F32 max_update_time)
 {
 	if (!gPipeline.hasRenderType(LLPipeline::RENDER_TYPE_TERRAIN))
 	{
-		return FALSE;
+		return false;
 	}
 	
 	// Perform idle time update of non-critical stuff.
 	// In this case, texture and normal updates.
 	LLTimer update_timer;
-	BOOL did_update = FALSE;
+	bool did_update = false;
 
 	// If the Z height data has changed, we need to rebuild our
 	// property line vertex arrays.
@@ -669,13 +670,13 @@ BOOL LLSurface::idleUpdate(F32 max_update_time)
 	{
 		std::set<LLSurfacePatch *>::iterator curiter = iter++;
 		LLSurfacePatch *patchp = *curiter;
-		patchp->updateNormals();
+		patchp->updateNormals<PBR>();
 		patchp->updateVerticalStats();
 		if (max_update_time == 0.f || update_timer.getElapsedTimeF32() < max_update_time)
 		{
 			if (patchp->updateTexture())
 			{
-				did_update = TRUE;
+				did_update = true;
 				patchp->clearDirty();
 				mDirtyPatchList.erase(curiter);
 			}
@@ -691,6 +692,9 @@ BOOL LLSurface::idleUpdate(F32 max_update_time)
 	return did_update;
 }
 
+template bool LLSurface::idleUpdate</*PBR=*/false>(F32 max_update_time);
+template bool LLSurface::idleUpdate</*PBR=*/true>(F32 max_update_time);
+
 void LLSurface::decompressDCTPatch(LLBitPack &bitpack, LLGroupHeader *gopp, BOOL b_large_patch) 
 {
 
diff --git a/indra/newview/llsurface.h b/indra/newview/llsurface.h
index 33a64ae7d5..b7b47d2a1c 100644
--- a/indra/newview/llsurface.h
+++ b/indra/newview/llsurface.h
@@ -112,7 +112,8 @@ public:
 	LLSurfacePatch *resolvePatchGlobal(const LLVector3d &position_global) const;
 
 	// Update methods (called during idle, normally)
-	BOOL idleUpdate(F32 max_update_time);
+    template<bool PBR>
+	bool idleUpdate(F32 max_update_time);
 
 	BOOL containsPosition(const LLVector3 &position);
 
@@ -224,6 +225,9 @@ private:
 	static S32	sTextureSize;				// Size of the surface texture
 };
 
+extern template bool LLSurface::idleUpdate</*PBR=*/false>(F32 max_update_time);
+extern template bool LLSurface::idleUpdate</*PBR=*/true>(F32 max_update_time);
+
 
 
 //        .   __.
diff --git a/indra/newview/llsurfacepatch.cpp b/indra/newview/llsurfacepatch.cpp
index 449d3d95c8..92b1273041 100644
--- a/indra/newview/llsurfacepatch.cpp
+++ b/indra/newview/llsurfacepatch.cpp
@@ -221,7 +221,9 @@ void LLSurfacePatch::eval(const U32 x, const U32 y, const U32 stride, LLVector3
 	*vertex     = pos_agent-mVObjp->getRegion()->getOriginAgent();
 
 	LLVector3 rel_pos = pos_agent - mSurfacep->getOriginAgent();
-	LLVector3 tex_pos = rel_pos * (1.f/surface_stride);
+	// *NOTE: Only PBR terrain uses the UVs right now. Texture terrain just ignores it.
+    // *NOTE: In the future, UVs and horizontal position will no longer have a 1:1 relationship for PBR terrain
+	LLVector3 tex_pos = rel_pos;
 	tex0->mV[0]  = tex_pos.mV[0];
 	tex0->mV[1]  = tex_pos.mV[1];
 	tex1->mV[0] = mSurfacep->getRegion()->getCompositionXY(llfloor(mOriginRegion.mV[0])+x, llfloor(mOriginRegion.mV[1])+y);
@@ -241,7 +243,8 @@ void LLSurfacePatch::eval(const U32 x, const U32 y, const U32 stride, LLVector3
 }
 
 
-void LLSurfacePatch::calcNormal(const U32 x, const U32 y, const U32 stride)
+template<>
+void LLSurfacePatch::calcNormal</*PBR=*/false>(const U32 x, const U32 y, const U32 stride)
 {
 	U32 patch_width = mSurfacep->mPVArray.mPatchWidth;
 	U32 surface_stride = mSurfacep->getGridsPerEdge();
@@ -354,6 +357,166 @@ void LLSurfacePatch::calcNormal(const U32 x, const U32 y, const U32 stride)
 	*(mDataNorm + surface_stride * y + x) = normal;
 }
 
+template<>
+void LLSurfacePatch::calcNormal</*PBR=*/true>(const U32 x, const U32 y, const U32 stride)
+{
+	llassert(mDataNorm);
+    constexpr U32 index = 0;
+
+	const U32 surface_stride = mSurfacep->getGridsPerEdge();
+	LLVector3& normal_out = *(mDataNorm + surface_stride * y + x);
+	calcNormalFlat(normal_out, x, y, index);
+}
+
+// Calculate the flat normal of a triangle whose least coordinate is specified by the given x,y values.
+// If index = 0, calculate the normal of the first triangle, otherwise calculate the normal of the second.
+void LLSurfacePatch::calcNormalFlat(LLVector3& normal_out, const U32 x, const U32 y, const U32 index)
+{
+    llassert(index == 0 || index == 1);
+
+	U32 patch_width = mSurfacep->mPVArray.mPatchWidth;
+	U32 surface_stride = mSurfacep->getGridsPerEdge();
+
+    // Vertex stride is always 1 because we want the flat surface of the current triangle face
+    constexpr U32 stride = 1;
+
+	const F32 mpg = mSurfacep->getMetersPerGrid() * stride;
+
+	S32 poffsets[2][2][2];
+	poffsets[0][0][0] = x;
+	poffsets[0][0][1] = y;
+
+	poffsets[0][1][0] = x;
+	poffsets[0][1][1] = y + stride;
+
+	poffsets[1][0][0] = x + stride;
+	poffsets[1][0][1] = y;
+
+	poffsets[1][1][0] = x + stride;
+	poffsets[1][1][1] = y + stride;
+
+	const LLSurfacePatch *ppatches[2][2];
+
+	// LLVector3 p1, p2, p3, p4;
+
+	ppatches[0][0] = this;
+	ppatches[0][1] = this;
+	ppatches[1][0] = this;
+	ppatches[1][1] = this;
+
+	U32 i, j;
+	for (i = 0; i < 2; i++)
+	{
+		for (j = 0; j < 2; j++)
+		{
+			if (poffsets[i][j][0] < 0)
+			{
+				if (!ppatches[i][j]->getNeighborPatch(WEST))
+				{
+					poffsets[i][j][0] = 0;
+				}
+				else
+				{
+					poffsets[i][j][0] += patch_width;
+					ppatches[i][j] = ppatches[i][j]->getNeighborPatch(WEST);
+				}
+			}
+			if (poffsets[i][j][1] < 0)
+			{
+				if (!ppatches[i][j]->getNeighborPatch(SOUTH))
+				{
+					poffsets[i][j][1] = 0;
+				}
+				else
+				{
+					poffsets[i][j][1] += patch_width;
+					ppatches[i][j] = ppatches[i][j]->getNeighborPatch(SOUTH);
+				}
+			}
+			if (poffsets[i][j][0] >= (S32)patch_width)
+			{
+				if (!ppatches[i][j]->getNeighborPatch(EAST))
+				{
+					poffsets[i][j][0] = patch_width - 1;
+				}
+				else
+				{
+					poffsets[i][j][0] -= patch_width;
+					ppatches[i][j] = ppatches[i][j]->getNeighborPatch(EAST);
+				}
+			}
+			if (poffsets[i][j][1] >= (S32)patch_width)
+			{
+				if (!ppatches[i][j]->getNeighborPatch(NORTH))
+				{
+					poffsets[i][j][1] = patch_width - 1;
+				}
+				else
+				{
+					poffsets[i][j][1] -= patch_width;
+					ppatches[i][j] = ppatches[i][j]->getNeighborPatch(NORTH);
+				}
+			}
+		}
+	}
+
+	LLVector3 p00(-mpg,-mpg,
+				  *(ppatches[0][0]->mDataZ
+				  + poffsets[0][0][0]
+				  + poffsets[0][0][1]*surface_stride));
+	LLVector3 p01(-mpg,+mpg,
+				  *(ppatches[0][1]->mDataZ
+				  + poffsets[0][1][0]
+				  + poffsets[0][1][1]*surface_stride));
+	LLVector3 p10(+mpg,-mpg,
+				  *(ppatches[1][0]->mDataZ
+				  + poffsets[1][0][0]
+				  + poffsets[1][0][1]*surface_stride));
+	LLVector3 p11(+mpg,+mpg,
+				  *(ppatches[1][1]->mDataZ
+				  + poffsets[1][1][0]
+				  + poffsets[1][1][1]*surface_stride));
+    
+    // Triangle index / coordinate convention
+    // for a single surface patch
+    //
+    // p01          p11
+    //
+    // ^   ._____. 
+    // |   |\    | 
+    // |   | \ 1 | 
+    // |   |  \  | 
+    //     | 0 \ | 
+    // y   |____\| 
+    //
+    // p00  x --->  p10
+    //
+    // (z up / out of the screen due to right-handed coordinate system)
+
+    LLVector3 normal;
+    if (index == 0)
+    {
+        LLVector3 c1 = p10 - p00;
+        LLVector3 c2 = p01 - p00;
+
+        normal = c1;
+        normal %= c2;
+        normal.normVec();
+    }
+    else // index == 1
+    {
+        LLVector3 c1 = p11 - p01;
+        LLVector3 c2 = p11 - p10;
+
+        normal = c1;
+        normal %= c2;
+        normal.normVec();
+    }
+
+	llassert(&normal_out);
+	normal_out = normal;
+}
+
 const LLVector3 &LLSurfacePatch::getNormal(const U32 x, const U32 y) const
 {
 	U32 surface_stride = mSurfacep->getGridsPerEdge();
@@ -451,6 +614,7 @@ void LLSurfacePatch::updateVerticalStats()
 }
 
 
+template<bool PBR>
 void LLSurfacePatch::updateNormals() 
 {
 	if (mSurfacep->mType == 'w')
@@ -468,9 +632,9 @@ void LLSurfacePatch::updateNormals()
 	{
 		for (j = 0; j <= grids_per_patch_edge; j++)
 		{
-			calcNormal(grids_per_patch_edge, j, 2);
-			calcNormal(grids_per_patch_edge - 1, j, 2);
-			calcNormal(grids_per_patch_edge - 2, j, 2);
+			calcNormal<PBR>(grids_per_patch_edge, j, 2);
+			calcNormal<PBR>(grids_per_patch_edge - 1, j, 2);
+			calcNormal<PBR>(grids_per_patch_edge - 2, j, 2);
 		}
 
 		dirty_patch = TRUE;
@@ -481,9 +645,9 @@ void LLSurfacePatch::updateNormals()
 	{
 		for (i = 0; i <= grids_per_patch_edge; i++)
 		{
-			calcNormal(i, grids_per_patch_edge, 2);
-			calcNormal(i, grids_per_patch_edge - 1, 2);
-			calcNormal(i, grids_per_patch_edge - 2, 2);
+			calcNormal<PBR>(i, grids_per_patch_edge, 2);
+			calcNormal<PBR>(i, grids_per_patch_edge - 1, 2);
+			calcNormal<PBR>(i, grids_per_patch_edge - 2, 2);
 		}
 
 		dirty_patch = TRUE;
@@ -494,8 +658,8 @@ void LLSurfacePatch::updateNormals()
 	{
 		for (j = 0; j < grids_per_patch_edge; j++)
 		{
-			calcNormal(0, j, 2);
-			calcNormal(1, j, 2);
+			calcNormal<PBR>(0, j, 2);
+			calcNormal<PBR>(1, j, 2);
 		}
 		dirty_patch = TRUE;
 	}
@@ -505,8 +669,8 @@ void LLSurfacePatch::updateNormals()
 	{
 		for (i = 0; i < grids_per_patch_edge; i++)
 		{
-			calcNormal(i, 0, 2);
-			calcNormal(i, 1, 2);
+			calcNormal<PBR>(i, 0, 2);
+			calcNormal<PBR>(i, 1, 2);
 		}
 		dirty_patch = TRUE;
 	}
@@ -582,10 +746,10 @@ void LLSurfacePatch::updateNormals()
 			// We've got a northeast patch in the same surface.
 			// The z and normals will be handled by that patch.
 		}
-		calcNormal(grids_per_patch_edge, grids_per_patch_edge, 2);
-		calcNormal(grids_per_patch_edge, grids_per_patch_edge - 1, 2);
-		calcNormal(grids_per_patch_edge - 1, grids_per_patch_edge, 2);
-		calcNormal(grids_per_patch_edge - 1, grids_per_patch_edge - 1, 2);
+		calcNormal<PBR>(grids_per_patch_edge, grids_per_patch_edge, 2);
+		calcNormal<PBR>(grids_per_patch_edge, grids_per_patch_edge - 1, 2);
+		calcNormal<PBR>(grids_per_patch_edge - 1, grids_per_patch_edge, 2);
+		calcNormal<PBR>(grids_per_patch_edge - 1, grids_per_patch_edge - 1, 2);
 		dirty_patch = TRUE;
 	}
 
@@ -596,7 +760,7 @@ void LLSurfacePatch::updateNormals()
 		{
 			for (i=2; i < grids_per_patch_edge - 2; i++)
 			{
-				calcNormal(i, j, 2);
+				calcNormal<PBR>(i, j, 2);
 			}
 		}
 		dirty_patch = TRUE;
@@ -613,6 +777,9 @@ void LLSurfacePatch::updateNormals()
 	}
 }
 
+template void LLSurfacePatch::updateNormals</*PBR=*/false>();
+template void LLSurfacePatch::updateNormals</*PBR=*/true>();
+
 void LLSurfacePatch::updateEastEdge()
 {
 	U32 grids_per_patch_edge = mSurfacep->getGridsPerPatchEdge();
@@ -739,7 +906,7 @@ void LLSurfacePatch::updateGL()
 	
 	updateCompositionStats();
 	F32 tex_patch_size = meters_per_grid*grids_per_patch_edge;
-	if (comp->generateTexture((F32)origin_region[VX], (F32)origin_region[VY],
+	if (comp->generateMinimapTileLand((F32)origin_region[VX], (F32)origin_region[VY],
 							  tex_patch_size, tex_patch_size))
 	{
 		mSTexUpdate = FALSE;
diff --git a/indra/newview/llsurfacepatch.h b/indra/newview/llsurfacepatch.h
index 8c8f501dce..ec3864ce44 100644
--- a/indra/newview/llsurfacepatch.h
+++ b/indra/newview/llsurfacepatch.h
@@ -77,6 +77,7 @@ public:
 
 	void updateVerticalStats();
 	void updateCompositionStats();
+    template<bool PBR>
 	void updateNormals();
 
 	void updateEastEdge();
@@ -102,9 +103,18 @@ public:
 	LLVector3 getPointAgent(const U32 x, const U32 y) const; // get the point at the offset.
 	LLVector2 getTexCoords(const U32 x, const U32 y) const;
 
+    // Per-vertex normals
+    // *TODO: PBR=true is a test implementation solely for proof-of-concept.
+    // Final implementation would likely be very different and may not even use
+    // this function. If we decide to keep calcNormalFlat, remove index as it
+    // is a debug parameter for testing.
+    template<bool PBR>
 	void calcNormal(const U32 x, const U32 y, const U32 stride);
 	const LLVector3 &getNormal(const U32 x, const U32 y) const;
 
+    // Per-triangle normals for flat edges
+	void calcNormalFlat(LLVector3& normal_out, const U32 x, const U32 y, const U32 index /* 0 or 1 */);
+
 	void eval(const U32 x, const U32 y, const U32 stride,
 				LLVector3 *vertex, LLVector3 *normal, LLVector2 *tex0, LLVector2 *tex1);
 	
@@ -181,5 +191,8 @@ protected:
 	LLSurface *mSurfacep; // Pointer to "parent" surface
 };
 
+extern template void LLSurfacePatch::updateNormals</*PBR=*/false>();
+extern template void LLSurfacePatch::updateNormals</*PBR=*/true>();
+
 
 #endif // LL_LLSURFACEPATCH_H
diff --git a/indra/newview/lltexturectrl.cpp b/indra/newview/lltexturectrl.cpp
index 62d3fa28bf..5415f9bd9a 100644
--- a/indra/newview/lltexturectrl.cpp
+++ b/indra/newview/lltexturectrl.cpp
@@ -72,6 +72,7 @@
 
 #include "llradiogroup.h"
 #include "llfloaterreg.h"
+#include "llgltfmaterialpreviewmgr.h"
 #include "lllocalbitmaps.h"
 #include "lllocalgltfmaterials.h"
 #include "llerror.h"
@@ -659,6 +660,7 @@ void LLFloaterTexturePicker::draw()
 	if( mOwner ) 
 	{
 		mTexturep = NULL;
+        LLPointer<LLFetchedGLTFMaterial> old_material = mGLTFMaterial;
         mGLTFMaterial = NULL;
         if (mImageAssetID.notNull())
         {
@@ -666,10 +668,27 @@ void LLFloaterTexturePicker::draw()
             {
                 mGLTFMaterial = (LLFetchedGLTFMaterial*) gGLTFMaterialList.getMaterial(mImageAssetID);
                 llassert(mGLTFMaterial == nullptr || dynamic_cast<LLFetchedGLTFMaterial*>(gGLTFMaterialList.getMaterial(mImageAssetID)) != nullptr);
+                if (mGLTFPreview.isNull() || mGLTFMaterial.isNull() || (old_material.notNull() && (old_material.get() != mGLTFMaterial.get())))
+                {
+                    // Only update the preview if needed, since gGLTFMaterialPreviewMgr does not cache the preview.
+                    if (mGLTFMaterial.isNull())
+                    {
+                        mGLTFPreview = nullptr;
+                    }
+                    else
+                    {
+                        mGLTFPreview = gGLTFMaterialPreviewMgr.getPreview(mGLTFMaterial);
+                    }
+                }
+                if (mGLTFPreview)
+                {
+                    mGLTFPreview->setBoostLevel(LLGLTexture::BOOST_PREVIEW);
+                }
             }
             else
             {
                 LLPointer<LLViewerFetchedTexture> texture = NULL;
+                mGLTFPreview = nullptr;
 
                 if (LLAvatarAppearanceDefines::LLAvatarAppearanceDictionary::isBakedImageId(mImageAssetID))
                 {
@@ -679,7 +698,7 @@ void LLFloaterTexturePicker::draw()
                     if (obj)
                     {
                         LLViewerTexture* viewerTexture = obj->getBakedTextureForMagicId(mImageAssetID);
-                        texture = viewerTexture ? dynamic_cast<LLViewerFetchedTexture*>(viewerTexture) : NULL;
+						texture = viewerTexture ? dynamic_cast<LLViewerFetchedTexture*>(viewerTexture) : NULL;
                     }
                 }
 
@@ -720,27 +739,25 @@ void LLFloaterTexturePicker::draw()
 
 		// If the floater is focused, don't apply its alpha to the texture (STORM-677).
 		const F32 alpha = getTransparencyType() == TT_ACTIVE ? 1.0f : getCurrentTransparency();
-        LLViewerTexture* texture = nullptr;
+        LLViewerTexture* preview;
         if (mGLTFMaterial)
         {
-            texture = mGLTFMaterial->getUITexture();
+            preview = mGLTFPreview.get();
         }
         else
         {
-            texture = mTexturep.get();
+            preview = mTexturep.get();
         }
 
-		if( texture )
+		if( preview )
 		{
-			if( texture->getComponents() == 4 )
+            preview->addTextureStats( (F32)(interior.getWidth() * interior.getHeight()) );
+			if( preview->getComponents() == 4 )
 			{
 				gl_rect_2d_checkerboard( interior, alpha );
 			}
 
-			gl_draw_scaled_image( interior.mLeft, interior.mBottom, interior.getWidth(), interior.getHeight(), texture, UI_VERTEX_COLOR % alpha );
-
-			// Pump the priority
-			texture->addTextureStats( (F32)(interior.getWidth() * interior.getHeight()) );
+			gl_draw_scaled_image( interior.mLeft, interior.mBottom, interior.getWidth(), interior.getHeight(), preview, UI_VERTEX_COLOR % alpha );
 		}
 		else if (!mFallbackImage.isNull())
 		{
@@ -1639,7 +1656,7 @@ LLTextureCtrl::LLTextureCtrl(const LLTextureCtrl::Params& p)
 	mShowLoadingPlaceholder( TRUE ),
 	mOpenTexPreview(false),
     mBakeTextureEnabled(true),
-    mInventoryPickType(PICK_TEXTURE),
+    mInventoryPickType(p.pick_type),
 	mImageAssetID(p.image_id),
 	mDefaultImageAssetID(p.default_image_id),
 	mDefaultImageName(p.default_image_name),
@@ -2157,48 +2174,73 @@ void LLTextureCtrl::draw()
 {
 	mBorder->setKeyboardFocusHighlight(hasFocus());
 
+    LLPointer<LLViewerTexture> preview = NULL;
+
 	if (!mValid)
 	{
 		mTexturep = NULL;
+        mGLTFMaterial = NULL;
+        mGLTFPreview = NULL;
 	}
 	else if (!mImageAssetID.isNull())
 	{
-		LLPointer<LLViewerFetchedTexture> texture = NULL;
-
 		if (LLAvatarAppearanceDefines::LLAvatarAppearanceDictionary::isBakedImageId(mImageAssetID))
 		{
 			LLViewerObject* obj = LLSelectMgr::getInstance()->getSelection()->getFirstObject();
 			if (obj)
 			{
 				LLViewerTexture* viewerTexture = obj->getBakedTextureForMagicId(mImageAssetID);
-				texture = viewerTexture ? dynamic_cast<LLViewerFetchedTexture*>(viewerTexture) : NULL;
+				mTexturep = viewerTexture ? dynamic_cast<LLViewerFetchedTexture*>(viewerTexture) : NULL;
+				mGLTFMaterial = NULL;
+				mGLTFPreview = NULL;
+
+                preview = mTexturep;
 			}
 			
 		}
 
-		if (texture.isNull())
+		if (preview.isNull())
 		{
+            LLPointer<LLFetchedGLTFMaterial> old_material = mGLTFMaterial;
+            mGLTFMaterial = NULL;
+            mTexturep = NULL;
             if (mInventoryPickType == PICK_MATERIAL)
             {
-                LLPointer<LLFetchedGLTFMaterial> material = gGLTFMaterialList.getMaterial(mImageAssetID);
-                if (material)
+                mGLTFMaterial = gGLTFMaterialList.getMaterial(mImageAssetID);
+                if (mGLTFPreview.isNull() || mGLTFMaterial.isNull() || (old_material.notNull() && (old_material.get() != mGLTFMaterial.get())))
+                {
+                    // Only update the preview if needed, since gGLTFMaterialPreviewMgr does not cache the preview.
+                    if (mGLTFMaterial.isNull())
+                    {
+                        mGLTFPreview = nullptr;
+                    }
+                    else
+                    {
+                        mGLTFPreview = gGLTFMaterialPreviewMgr.getPreview(mGLTFMaterial);
+                    }
+                }
+                if (mGLTFPreview)
                 {
-                    texture = material->getUITexture();
+                    mGLTFPreview->setBoostLevel(LLGLTexture::BOOST_PREVIEW);
                 }
+
+                preview = mGLTFPreview;
             }
             else
             {
-                texture = LLViewerTextureManager::getFetchedTexture(mImageAssetID, FTT_DEFAULT, TRUE, LLGLTexture::BOOST_NONE, LLViewerTexture::LOD_TEXTURE);
-                texture->setBoostLevel(LLGLTexture::BOOST_PREVIEW);
-                texture->forceToSaveRawImage(0);
+				mTexturep = LLViewerTextureManager::getFetchedTexture(mImageAssetID, FTT_DEFAULT, TRUE, LLGLTexture::BOOST_NONE, LLViewerTexture::LOD_TEXTURE);
+				mTexturep->setBoostLevel(LLGLTexture::BOOST_PREVIEW);
+				mTexturep->forceToSaveRawImage(0);
+
+				preview = mTexturep;
             }
 		}
-
-		mTexturep = texture;
 	}
 	else//mImageAssetID == LLUUID::null
 	{
 		mTexturep = NULL; 
+        mGLTFMaterial = NULL;
+        mGLTFPreview = NULL;
 	}
 	
 	// Border
@@ -2211,15 +2253,15 @@ void LLTextureCtrl::draw()
 
 	// If we're in a focused floater, don't apply the floater's alpha to the texture (STORM-677).
 	const F32 alpha = getTransparencyType() == TT_ACTIVE ? 1.0f : getCurrentTransparency();
-	if( mTexturep )
+	if( preview )
 	{
-		if( mTexturep->getComponents() == 4 )
+		if( preview->getComponents() == 4 )
 		{
 			gl_rect_2d_checkerboard( interior, alpha );
 		}
 		
-		gl_draw_scaled_image( interior.mLeft, interior.mBottom, interior.getWidth(), interior.getHeight(), mTexturep, UI_VERTEX_COLOR % alpha);
-		mTexturep->addTextureStats( (F32)(interior.getWidth() * interior.getHeight()) );
+		gl_draw_scaled_image( interior.mLeft, interior.mBottom, interior.getWidth(), interior.getHeight(), preview, UI_VERTEX_COLOR % alpha);
+        preview->addTextureStats( (F32)(interior.getWidth() * interior.getHeight()) );
 	}
 	else if (!mFallbackImage.isNull())
 	{
@@ -2366,6 +2408,16 @@ LLSD LLTextureCtrl::getValue() const
 	return LLSD(getImageAssetID());
 }
 
+namespace LLInitParam
+{
+    void TypeValues<EPickInventoryType>::declareValues()
+    {
+        declare("texture_material", PICK_TEXTURE_MATERIAL);
+        declare("texture", PICK_TEXTURE);
+        declare("material", PICK_MATERIAL);
+    }
+}
+
 
 
 
diff --git a/indra/newview/lltexturectrl.h b/indra/newview/lltexturectrl.h
index cb6ce636e0..05ea185b1b 100644
--- a/indra/newview/lltexturectrl.h
+++ b/indra/newview/lltexturectrl.h
@@ -64,13 +64,6 @@ bool get_is_predefined_texture(LLUUID asset_id);
 LLUUID get_copy_free_item_by_asset_id(LLUUID image_id, bool no_trans_perm = false);
 bool get_can_copy_texture(LLUUID image_id);
 
-enum LLPickerSource
-{
-    PICKER_INVENTORY,
-    PICKER_LOCAL,
-    PICKER_BAKE,
-    PICKER_UNKNOWN, // on cancel, default ids
-};
 
 typedef enum e_pick_inventory_type
 {
@@ -79,6 +72,23 @@ typedef enum e_pick_inventory_type
     PICK_MATERIAL = 2,
 } EPickInventoryType;
 
+namespace LLInitParam
+{
+    template<>
+	struct TypeValues<EPickInventoryType> : public TypeValuesHelper<EPickInventoryType>
+	{
+		static void declareValues();
+	};
+}
+
+enum LLPickerSource
+{
+    PICKER_INVENTORY,
+    PICKER_LOCAL,
+    PICKER_BAKE,
+    PICKER_UNKNOWN, // on cancel, default ids
+};
+
 //////////////////////////////////////////////////////////////////////////////////////////
 // LLTextureCtrl
 
@@ -100,6 +110,7 @@ public:
 		Optional<LLUUID>		image_id;
 		Optional<LLUUID>		default_image_id;
 		Optional<std::string>	default_image_name;
+        Optional<EPickInventoryType> pick_type;
 		Optional<bool>			allow_no_texture;
 		Optional<bool>			can_apply_immediately;
 		Optional<bool>			no_commit_on_selection; // alternative mode: commit occurs and the widget gets dirty
@@ -117,6 +128,7 @@ public:
 		:	image_id("image"),
 			default_image_id("default_image_id"),
 			default_image_name("default_image_name"),
+            pick_type("pick_type", PICK_TEXTURE),
 			allow_no_texture("allow_no_texture", false),
 			can_apply_immediately("can_apply_immediately"),
 			no_commit_on_selection("no_commit_on_selection", false),
@@ -250,6 +262,8 @@ private:
 	commit_callback_t		 	mOnCloseCallback;
 	texture_selected_callback	mOnTextureSelectedCallback;
 	LLPointer<LLViewerFetchedTexture> mTexturep;
+	LLPointer<LLFetchedGLTFMaterial> mGLTFMaterial;
+	LLPointer<LLViewerTexture> mGLTFPreview;
 	LLUIColor				 	mBorderColor;
 	LLUUID					 	mImageItemID;
 	LLUUID					 	mImageAssetID;
@@ -382,6 +396,7 @@ protected:
 
 	LLPointer<LLViewerTexture> mTexturep;
     LLPointer<LLFetchedGLTFMaterial> mGLTFMaterial;
+    LLPointer<LLViewerTexture> mGLTFPreview;
 	LLView*				mOwner;
 
 	LLUUID				mImageAssetID; // Currently selected texture
diff --git a/indra/newview/llviewercamera.cpp b/indra/newview/llviewercamera.cpp
index 4134e35f87..9ba42e4f47 100644
--- a/indra/newview/llviewercamera.cpp
+++ b/indra/newview/llviewercamera.cpp
@@ -764,6 +764,12 @@ BOOL LLViewerCamera::cameraUnderWater() const
 {
     LLViewerRegion* regionp = LLWorld::instance().getRegionFromPosAgent(getOrigin());
 
+    if (gPipeline.mHeroProbeManager.isMirrorPass())
+    {
+        // TODO: figure out how to handle this case
+        return FALSE;
+    }
+
     if (!regionp)
     {
         regionp = gAgent.getRegion();
diff --git a/indra/newview/llviewercontrol.cpp b/indra/newview/llviewercontrol.cpp
index 7738cb904e..ba1add9b92 100644
--- a/indra/newview/llviewercontrol.cpp
+++ b/indra/newview/llviewercontrol.cpp
@@ -54,6 +54,7 @@
 #include "llvotree.h"
 #include "llvovolume.h"
 #include "llworld.h"
+#include "llvlcomposition.h"
 #include "pipeline.h"
 #include "llviewerjoystick.h"
 #include "llviewerobjectlist.h"
@@ -117,12 +118,25 @@ static bool handleRenderFarClipChanged(const LLSD& newvalue)
     return false;
 }
 
-static bool handleTerrainDetailChanged(const LLSD& newvalue)
+static bool handleTerrainScaleChanged(const LLSD& newvalue)
 {
-	LLDrawPoolTerrain::sDetailMode = newvalue.asInteger();
+    F64 scale = newvalue.asReal();
+    if (scale != 0.0)
+    {
+        LLDrawPoolTerrain::sDetailScale = F32(1.0 / scale);
+    }
 	return true;
 }
 
+static bool handlePBRTerrainScaleChanged(const LLSD& newvalue)
+{
+    F64 scale = newvalue.asReal();
+    if (scale != 0.0)
+    {
+        LLDrawPoolTerrain::sPBRDetailScale = F32(1.0 / scale);
+    }
+	return true;
+}
 
 static bool handleDebugAvatarJointsChanged(const LLSD& newvalue)
 {
@@ -650,6 +664,16 @@ void handleFPSTuningStrategyChanged(const LLSD& newValue)
     const auto newval = gSavedSettings.getU32("TuningFPSStrategy");
     LLPerfStats::tunables.userFPSTuningStrategy = newval;
 }
+
+void handleLocalTerrainChanged(const LLSD& newValue)
+{
+    for (U32 i = 0; i < LLTerrainMaterials::ASSET_COUNT; ++i)
+    {
+        const auto setting = gSavedSettings.getString(std::string("LocalTerrainAsset") + std::to_string(i + 1));
+        const LLUUID materialID(setting);
+        gLocalTerrainMaterials.setDetailAssetID(i, materialID);
+    }
+}
 ////////////////////////////////////////////////////////////////////////////
 
 LLPointer<LLControlVariable> setting_get_control(LLControlGroup& group, const std::string& setting)
@@ -684,7 +708,11 @@ void settings_setup_listeners()
 {
     setting_setup_signal_listener(gSavedSettings, "FirstPersonAvatarVisible", handleRenderAvatarMouselookChanged);
     setting_setup_signal_listener(gSavedSettings, "RenderFarClip", handleRenderFarClipChanged);
-    setting_setup_signal_listener(gSavedSettings, "RenderTerrainDetail", handleTerrainDetailChanged);
+    setting_setup_signal_listener(gSavedSettings, "RenderTerrainScale", handleTerrainScaleChanged);
+    setting_setup_signal_listener(gSavedSettings, "RenderTerrainPBRScale", handlePBRTerrainScaleChanged);
+    setting_setup_signal_listener(gSavedSettings, "RenderTerrainPBRDetail", handleSetShaderChanged);
+    setting_setup_signal_listener(gSavedSettings, "RenderTerrainPBRPlanarSampleCount", handleSetShaderChanged);
+    setting_setup_signal_listener(gSavedSettings, "RenderTerrainPBRTriplanarBlendFactor", handleSetShaderChanged);
     setting_setup_signal_listener(gSavedSettings, "OctreeStaticObjectSizeFactor", handleRepartition);
     setting_setup_signal_listener(gSavedSettings, "OctreeDistanceFactor", handleRepartition);
     setting_setup_signal_listener(gSavedSettings, "OctreeMaxNodeCapacity", handleRepartition);
@@ -830,6 +858,10 @@ void settings_setup_listeners()
     setting_setup_signal_listener(gSavedSettings, "AutoTuneImpostorFarAwayDistance", handleUserImpostorDistanceChanged);
     setting_setup_signal_listener(gSavedSettings, "AutoTuneImpostorByDistEnabled", handleUserImpostorByDistEnabledChanged);
     setting_setup_signal_listener(gSavedSettings, "TuningFPSStrategy", handleFPSTuningStrategyChanged);
+    setting_setup_signal_listener(gSavedSettings, "LocalTerrainAsset1", handleLocalTerrainChanged);
+    setting_setup_signal_listener(gSavedSettings, "LocalTerrainAsset2", handleLocalTerrainChanged);
+    setting_setup_signal_listener(gSavedSettings, "LocalTerrainAsset3", handleLocalTerrainChanged);
+    setting_setup_signal_listener(gSavedSettings, "LocalTerrainAsset4", handleLocalTerrainChanged);
 
     setting_setup_signal_listener(gSavedPerAccountSettings, "AvatarHoverOffsetZ", handleAvatarHoverOffsetChanged);
 }
diff --git a/indra/newview/llviewerdisplay.cpp b/indra/newview/llviewerdisplay.cpp
index e1d6f71cce..e6d9aed1a3 100644
--- a/indra/newview/llviewerdisplay.cpp
+++ b/indra/newview/llviewerdisplay.cpp
@@ -656,6 +656,14 @@ void display(BOOL rebuild, F32 zoom_factor, int subfield, BOOL for_snapshot)
 	
 	if (!gDisconnected)
 	{
+		// Render mirrors and associated hero probes before we render the rest of the scene.
+		// This ensures the scene state in the hero probes are exactly the same as the rest of the scene before we render it.
+        if (gPipeline.RenderMirrors && !gSnapshot)
+        {
+            LL_PROFILE_ZONE_NAMED_CATEGORY_DISPLAY("Update hero probes");
+            gPipeline.mHeroProbeManager.update();
+        }
+
 		LL_PROFILE_ZONE_NAMED_CATEGORY_DISPLAY("display - 1");
 		LLAppViewer::instance()->pingMainloopTimeout("Display:Update");
 		if (gPipeline.hasRenderType(LLPipeline::RENDER_TYPE_HUD))
@@ -696,7 +704,7 @@ void display(BOOL rebuild, F32 zoom_factor, int subfield, BOOL for_snapshot)
 		}
 
 		gPipeline.updateGL();
-		
+
 		stop_glerror();
 
 		LLAppViewer::instance()->pingMainloopTimeout("Display:Cull");
@@ -1064,7 +1072,7 @@ void display_cube_face()
     LLSpatialGroup::sNoDelete = TRUE;
         
     S32 occlusion = LLPipeline::sUseOcclusion;
-    LLPipeline::sUseOcclusion = 0; // occlusion data is from main camera point of view, don't read or write it during cube snapshots
+    LLPipeline::sUseOcclusion = 1; // occlusion data is from main camera point of view, don't read or write it during cube snapshots
     //gDepthDirty = TRUE; //let "real" render pipe know it can't trust the depth buffer for occlusion data
 
     static LLCullResult result;
diff --git a/indra/newview/llviewermenu.cpp b/indra/newview/llviewermenu.cpp
index 9db9d97ddc..da7b1131a3 100644
--- a/indra/newview/llviewermenu.cpp
+++ b/indra/newview/llviewermenu.cpp
@@ -2122,6 +2122,20 @@ class LLAdvancedPurgeShaderCache : public view_listener_t
 	}
 };
 
+/////////////////////
+// REBUILD TERRAIN //
+/////////////////////
+
+
+class LLAdvancedRebuildTerrain : public view_listener_t
+{
+	bool handleEvent(const LLSD& userdata)
+	{
+        gPipeline.rebuildTerrain();
+		return true;
+	}
+};
+
 ////////////////////
 // EVENT Recorder //
 ///////////////////
@@ -9492,6 +9506,10 @@ void initialize_menus()
 	view_listener_t::addMenu(new LLAdvancedClickRenderProfile(), "Advanced.ClickRenderProfile");
 	view_listener_t::addMenu(new LLAdvancedClickRenderBenchmark(), "Advanced.ClickRenderBenchmark");
 	view_listener_t::addMenu(new LLAdvancedPurgeShaderCache(), "Advanced.ClearShaderCache");
+    if (gSavedSettings.get<bool>("RenderTerrainPBREnabled"))
+    {
+        view_listener_t::addMenu(new LLAdvancedRebuildTerrain(), "Advanced.RebuildTerrain");
+    }
 
 	#ifdef TOGGLE_HACKED_GODLIKE_VIEWER
 	view_listener_t::addMenu(new LLAdvancedHandleToggleHackedGodmode(), "Advanced.HandleToggleHackedGodmode");
diff --git a/indra/newview/llviewerobject.cpp b/indra/newview/llviewerobject.cpp
index a741f57753..d71814bd3f 100644
--- a/indra/newview/llviewerobject.cpp
+++ b/indra/newview/llviewerobject.cpp
@@ -1522,12 +1522,13 @@ U32 LLViewerObject::processUpdateMessage(LLMessageSystem *mesgsys,
 
 					std::string temp_string;
 					mesgsys->getStringFast(_PREHASH_ObjectData, _PREHASH_Text, temp_string, block_num );
-					
+                    
 					LLColor4U coloru;
 					mesgsys->getBinaryDataFast(_PREHASH_ObjectData, _PREHASH_TextColor, coloru.mV, 4, block_num);
-
+                        
 					// alpha was flipped so that it zero encoded better
 					coloru.mV[3] = 255 - coloru.mV[3];
+                    
 					mText->setColor(LLColor4(coloru));
 					mText->setString(temp_string);
 
@@ -1907,6 +1908,7 @@ U32 LLViewerObject::processUpdateMessage(LLMessageSystem *mesgsys,
 				{
 					std::string temp_string;
 					dp->unpackString(temp_string, "Text");
+                    
 					LLColor4U coloru;
 					dp->unpackBinaryDataFixed(coloru.mV, 4, "Color");
 					coloru.mV[3] = 255 - coloru.mV[3];
@@ -5349,7 +5351,6 @@ S32 LLViewerObject::setTEFullbright(const U8 te, const U8 fullbright)
 	return retval;
 }
 
-
 S32 LLViewerObject::setTEMediaFlags(const U8 te, const U8 media_flags)
 {
 	// this might need work for media type
diff --git a/indra/newview/llviewerregion.cpp b/indra/newview/llviewerregion.cpp
index 60862ae5bd..5b51267cbe 100755
--- a/indra/newview/llviewerregion.cpp
+++ b/indra/newview/llviewerregion.cpp
@@ -1105,6 +1105,11 @@ void LLViewerRegion::dirtyHeights()
 	}
 }
 
+void LLViewerRegion::dirtyAllPatches()
+{
+    getLand().dirtyAllPatches();
+}
+
 //physically delete the cache entry
 void LLViewerRegion::killCacheEntry(LLVOCacheEntry* entry, bool for_rendering)
 {	
@@ -1605,7 +1610,19 @@ void LLViewerRegion::idleUpdate(F32 max_update_time)
 
 	mLastUpdate = LLViewerOctreeEntryData::getCurrentFrame();
 
-	mImpl->mLandp->idleUpdate(max_update_time);
+    static bool pbr_terrain_enabled = gSavedSettings.get<bool>("RenderTerrainPBREnabled");
+    static LLCachedControl<bool> pbr_terrain_experimental_normals(gSavedSettings, "RenderTerrainPBRNormalsEnabled", FALSE);
+    bool pbr_material = mImpl->mCompositionp && (mImpl->mCompositionp->getMaterialType() == LLTerrainMaterials::Type::PBR);
+    bool pbr_land = pbr_material && pbr_terrain_enabled && pbr_terrain_experimental_normals;
+
+    if (!pbr_land)
+    {
+        mImpl->mLandp->idleUpdate</*PBR=*/false>(max_update_time);
+    }
+    else
+    {
+        mImpl->mLandp->idleUpdate</*PBR=*/true>(max_update_time);
+    }
 	
 	if (mParcelOverlay)
 	{
@@ -1906,7 +1923,21 @@ LLViewerObject* LLViewerRegion::updateCacheEntry(U32 local_id, LLViewerObject* o
 // As above, but forcibly do the update.
 void LLViewerRegion::forceUpdate()
 {
-	mImpl->mLandp->idleUpdate(0.f);
+	constexpr F32 max_update_time = 0.f;
+
+	static bool pbr_terrain_enabled = gSavedSettings.get<BOOL>("RenderTerrainPBREnabled");
+	static LLCachedControl<BOOL> pbr_terrain_experimental_normals(gSavedSettings, "RenderTerrainPBRNormalsEnabled", FALSE);
+	bool pbr_material = mImpl->mCompositionp && (mImpl->mCompositionp->getMaterialType() == LLTerrainMaterials::Type::PBR);
+	bool pbr_land = pbr_material && pbr_terrain_enabled && pbr_terrain_experimental_normals;
+
+	if (!pbr_land)
+	{
+		mImpl->mLandp->idleUpdate</*PBR=*/false>(max_update_time);
+	}
+	else
+	{
+		mImpl->mLandp->idleUpdate</*PBR=*/true>(max_update_time);
+	}
 
 	if (mParcelOverlay)
 	{
@@ -2407,7 +2438,37 @@ void LLViewerRegion::setSimulatorFeatures(const LLSD& sim_features)
 	mSimulatorFeatures = sim_features;
 
 	setSimulatorFeaturesReceived(true);
-	
+
+    // if region has MaxTextureResolution, set max_texture_dimension settings, otherwise use default
+    if (mSimulatorFeatures.has("MaxTextureResolution"))
+    {
+        S32 max_texture_resolution = mSimulatorFeatures["MaxTextureResolution"].asInteger();
+        gSavedSettings.setS32("max_texture_dimension_X", max_texture_resolution);
+        gSavedSettings.setS32("max_texture_dimension_Y", max_texture_resolution);
+    }
+    else
+    {
+        gSavedSettings.setS32("max_texture_dimension_X", 1024);
+        gSavedSettings.setS32("max_texture_dimension_Y", 1024);
+    }
+
+    bool mirrors_enabled = false;
+    if (mSimulatorFeatures.has("MirrorsEnabled"))
+    {
+        mirrors_enabled = mSimulatorFeatures["MirrorsEnabled"].asBoolean();
+    }
+
+    gSavedSettings.setBOOL("RenderMirrors", mirrors_enabled);
+
+    if (mSimulatorFeatures.has("PBRMaterialSwatchEnabled"))
+    {
+        bool enabled = mSimulatorFeatures["PBRMaterialSwatchEnabled"];
+        gSavedSettings.setBOOL("UIPreviewMaterial", enabled);
+    }
+    else
+    {
+        gSavedSettings.setBOOL("UIPreviewMaterial", false);
+    }
 }
 
 //this is called when the parent is not cacheable.
@@ -2963,20 +3024,20 @@ void LLViewerRegion::unpackRegionHandshake()
 
 		// Get the 4 textures for land
 		msg->getUUID("RegionInfo", "TerrainDetail0", tmp_id);
-		changed |= (tmp_id != compp->getDetailTextureID(0));		
-		compp->setDetailTextureID(0, tmp_id);
+		changed |= (tmp_id != compp->getDetailAssetID(0));		
+		compp->setDetailAssetID(0, tmp_id);
 
 		msg->getUUID("RegionInfo", "TerrainDetail1", tmp_id);
-		changed |= (tmp_id != compp->getDetailTextureID(1));		
-		compp->setDetailTextureID(1, tmp_id);
+		changed |= (tmp_id != compp->getDetailAssetID(1));		
+		compp->setDetailAssetID(1, tmp_id);
 
 		msg->getUUID("RegionInfo", "TerrainDetail2", tmp_id);
-		changed |= (tmp_id != compp->getDetailTextureID(2));		
-		compp->setDetailTextureID(2, tmp_id);
+		changed |= (tmp_id != compp->getDetailAssetID(2));		
+		compp->setDetailAssetID(2, tmp_id);
 
 		msg->getUUID("RegionInfo", "TerrainDetail3", tmp_id);
-		changed |= (tmp_id != compp->getDetailTextureID(3));		
-		compp->setDetailTextureID(3, tmp_id);
+		changed |= (tmp_id != compp->getDetailAssetID(3));		
+		compp->setDetailAssetID(3, tmp_id);
 
 		// Get the start altitude and range values for land textures
 		F32 tmp_f32;
diff --git a/indra/newview/llviewerregion.h b/indra/newview/llviewerregion.h
index 622490c881..1c2ff9bc97 100644
--- a/indra/newview/llviewerregion.h
+++ b/indra/newview/llviewerregion.h
@@ -163,6 +163,9 @@ public:
 	// Call this whenever you change the height data in the region.
 	// (Automatically called by LLSurfacePatch's update routine)
 	void dirtyHeights();
+    // Call this whenever you want to force all terrain to rebuild.
+    // (For example, if a global terrain config option has changed)
+    void dirtyAllPatches();
 
 	LLViewerParcelOverlay *getParcelOverlay() const
 			{ return mParcelOverlay; }
diff --git a/indra/newview/llviewershadermgr.cpp b/indra/newview/llviewershadermgr.cpp
index 3225299493..4eb934114d 100644
--- a/indra/newview/llviewershadermgr.cpp
+++ b/indra/newview/llviewershadermgr.cpp
@@ -69,6 +69,14 @@ bool				LLViewerShaderMgr::sSkipReload = false;
 
 LLVector4			gShinyOrigin;
 
+S32 clamp_terrain_mapping(S32 mapping)
+{
+    // 1 = "flat", 2 not implemented, 3 = triplanar mapping
+    mapping = llclamp(mapping, 1, 3);
+    if (mapping == 2) { mapping = 1; }
+    return mapping;
+}
+
 //utility shaders
 LLGLSLShader	gOcclusionProgram;
 LLGLSLShader    gSkinnedOcclusionProgram;
@@ -76,13 +84,16 @@ LLGLSLShader	gOcclusionCubeProgram;
 LLGLSLShader	gGlowCombineProgram;
 LLGLSLShader	gReflectionMipProgram;
 LLGLSLShader    gGaussianProgram;
-LLGLSLShader	gRadianceGenProgram;
+LLGLSLShader    gRadianceGenProgram;
+LLGLSLShader    gHeroRadianceGenProgram;
 LLGLSLShader	gIrradianceGenProgram;
 LLGLSLShader	gGlowCombineFXAAProgram;
 LLGLSLShader	gTwoTextureCompareProgram;
 LLGLSLShader	gOneTextureFilterProgram;
 LLGLSLShader	gDebugProgram;
 LLGLSLShader    gSkinnedDebugProgram;
+LLGLSLShader	gNormalDebugProgram[NORMAL_DEBUG_SHADER_COUNT];
+LLGLSLShader	gSkinnedNormalDebugProgram[NORMAL_DEBUG_SHADER_COUNT];
 LLGLSLShader	gClipProgram;
 LLGLSLShader	gAlphaMaskProgram;
 LLGLSLShader	gBenchmarkProgram;
@@ -95,7 +106,6 @@ LLGLSLShader		gObjectPreviewProgram;
 LLGLSLShader        gSkinnedObjectPreviewProgram;
 LLGLSLShader        gPhysicsPreviewProgram;
 LLGLSLShader		gObjectFullbrightAlphaMaskProgram;
-LLGLSLShader        gSkinnedObjectFullbrightAlphaMaskProgram;
 LLGLSLShader		gObjectBumpProgram;
 LLGLSLShader        gSkinnedObjectBumpProgram;
 LLGLSLShader		gObjectAlphaMaskNoColorProgram;
@@ -214,9 +224,10 @@ LLGLSLShader            gDeferredSkinnedPBROpaqueProgram;
 LLGLSLShader            gHUDPBRAlphaProgram;
 LLGLSLShader            gDeferredPBRAlphaProgram;
 LLGLSLShader            gDeferredSkinnedPBRAlphaProgram;
+LLGLSLShader			gDeferredPBRTerrainProgram;
 
 //helper for making a rigged variant of a given shader
-bool make_rigged_variant(LLGLSLShader& shader, LLGLSLShader& riggedShader)
+static bool make_rigged_variant(LLGLSLShader& shader, LLGLSLShader& riggedShader)
 {
     riggedShader.mName = llformat("Skinned %s", shader.mName.c_str());
     riggedShader.mFeatures = shader.mFeatures;
@@ -231,64 +242,98 @@ bool make_rigged_variant(LLGLSLShader& shader, LLGLSLShader& riggedShader)
     return riggedShader.createShader(NULL, NULL);
 }
 
+#ifdef SHOW_ASSERT
+// return true if there are no redundant shaders in the given vector
+// also checks for redundant variants
+static bool no_redundant_shaders(const std::vector<LLGLSLShader*>& shaders)
+{
+    std::set<std::string> names;
+    for (LLGLSLShader* shader : shaders)
+    {
+        if (names.find(shader->mName) != names.end())
+        {
+            LL_WARNS("Shader") << "Redundant shader: " << shader->mName << LL_ENDL;
+            return false;
+        }
+        names.insert(shader->mName);
+
+        if (shader->mRiggedVariant)
+        {
+            if (names.find(shader->mRiggedVariant->mName) != names.end())
+            {
+                LL_WARNS("Shader") << "Redundant shader: " << shader->mRiggedVariant->mName << LL_ENDL;
+                return false;
+            }
+            names.insert(shader->mRiggedVariant->mName);
+        }
+    }
+    return true;
+}
+#endif
+
+
 LLViewerShaderMgr::LLViewerShaderMgr() :
 	mShaderLevel(SHADER_COUNT, 0),
 	mMaxAvatarShaderLevel(0)
 {   
+}
+
+LLViewerShaderMgr::~LLViewerShaderMgr()
+{
+	mShaderLevel.clear();
+	mShaderList.clear();
+}
+
+void LLViewerShaderMgr::finalizeShaderList()
+{
     //ONLY shaders that need WL Param management should be added here
-	mShaderList.push_back(&gAvatarProgram);
-	mShaderList.push_back(&gWaterProgram);
-	mShaderList.push_back(&gWaterEdgeProgram);
-	mShaderList.push_back(&gAvatarEyeballProgram); 
-	mShaderList.push_back(&gImpostorProgram);
-	mShaderList.push_back(&gObjectBumpProgram);
-    mShaderList.push_back(&gSkinnedObjectBumpProgram);
-	mShaderList.push_back(&gObjectFullbrightAlphaMaskProgram);
-    mShaderList.push_back(&gSkinnedObjectFullbrightAlphaMaskProgram);
-	mShaderList.push_back(&gObjectAlphaMaskNoColorProgram);
-	mShaderList.push_back(&gUnderWaterProgram);
-	mShaderList.push_back(&gDeferredSunProgram);
+    mShaderList.push_back(&gAvatarProgram);
+    mShaderList.push_back(&gWaterProgram);
+    mShaderList.push_back(&gWaterEdgeProgram);
+    mShaderList.push_back(&gAvatarEyeballProgram);
+    mShaderList.push_back(&gImpostorProgram);
+    mShaderList.push_back(&gObjectBumpProgram);
+    mShaderList.push_back(&gObjectFullbrightAlphaMaskProgram);
+    mShaderList.push_back(&gObjectAlphaMaskNoColorProgram);
+    mShaderList.push_back(&gUnderWaterProgram);
+    mShaderList.push_back(&gDeferredSunProgram);
     mShaderList.push_back(&gHazeProgram);
     mShaderList.push_back(&gHazeWaterProgram);
-	mShaderList.push_back(&gDeferredSoftenProgram);
-	mShaderList.push_back(&gDeferredAlphaProgram);
+    mShaderList.push_back(&gDeferredSoftenProgram);
+    mShaderList.push_back(&gDeferredAlphaProgram);
     mShaderList.push_back(&gHUDAlphaProgram);
-    mShaderList.push_back(&gDeferredSkinnedAlphaProgram);
-	mShaderList.push_back(&gDeferredAlphaImpostorProgram);
-    mShaderList.push_back(&gDeferredSkinnedAlphaImpostorProgram);
-	mShaderList.push_back(&gDeferredFullbrightProgram);
+    mShaderList.push_back(&gDeferredAlphaImpostorProgram);
+    mShaderList.push_back(&gDeferredFullbrightProgram);
     mShaderList.push_back(&gHUDFullbrightProgram);
-	mShaderList.push_back(&gDeferredFullbrightAlphaMaskProgram);
+    mShaderList.push_back(&gDeferredFullbrightAlphaMaskProgram);
     mShaderList.push_back(&gHUDFullbrightAlphaMaskProgram);
     mShaderList.push_back(&gDeferredFullbrightAlphaMaskAlphaProgram);
     mShaderList.push_back(&gHUDFullbrightAlphaMaskAlphaProgram);
-	mShaderList.push_back(&gDeferredFullbrightShinyProgram);
+    mShaderList.push_back(&gDeferredFullbrightShinyProgram);
     mShaderList.push_back(&gHUDFullbrightShinyProgram);
-    mShaderList.push_back(&gDeferredSkinnedFullbrightShinyProgram);
-	mShaderList.push_back(&gDeferredSkinnedFullbrightProgram);
-    mShaderList.push_back(&gDeferredSkinnedFullbrightAlphaMaskProgram);
-    mShaderList.push_back(&gDeferredSkinnedFullbrightAlphaMaskAlphaProgram);
-	mShaderList.push_back(&gDeferredEmissiveProgram);
-    mShaderList.push_back(&gDeferredSkinnedEmissiveProgram);
-	mShaderList.push_back(&gDeferredAvatarEyesProgram);
+    mShaderList.push_back(&gDeferredEmissiveProgram);
+    mShaderList.push_back(&gDeferredAvatarEyesProgram);
     mShaderList.push_back(&gDeferredAvatarAlphaProgram);
-	mShaderList.push_back(&gDeferredWLSkyProgram);
-	mShaderList.push_back(&gDeferredWLCloudProgram);
+    mShaderList.push_back(&gDeferredWLSkyProgram);
+    mShaderList.push_back(&gDeferredWLCloudProgram);
     mShaderList.push_back(&gDeferredWLMoonProgram);
     mShaderList.push_back(&gDeferredWLSunProgram);
     mShaderList.push_back(&gDeferredPBRAlphaProgram);
     mShaderList.push_back(&gHUDPBRAlphaProgram);
-    mShaderList.push_back(&gDeferredSkinnedPBRAlphaProgram);
     mShaderList.push_back(&gDeferredPostGammaCorrectProgram); // for gamma
     mShaderList.push_back(&gNoPostGammaCorrectProgram);
     mShaderList.push_back(&gLegacyPostGammaCorrectProgram);
-
-}
-
-LLViewerShaderMgr::~LLViewerShaderMgr()
-{
-	mShaderLevel.clear();
-	mShaderList.clear();
+    mShaderList.push_back(&gDeferredDiffuseProgram);
+    mShaderList.push_back(&gDeferredBumpProgram);
+    mShaderList.push_back(&gDeferredPBROpaqueProgram);
+    mShaderList.push_back(&gDeferredAvatarProgram);
+    mShaderList.push_back(&gDeferredTerrainProgram);
+    mShaderList.push_back(&gDeferredDiffuseAlphaMaskProgram);
+    mShaderList.push_back(&gDeferredNonIndexedDiffuseAlphaMaskProgram);
+    mShaderList.push_back(&gDeferredTreeProgram);
+
+    // make sure there are no redundancies 
+    llassert(no_redundant_shaders(mShaderList));
 }
 
 // static
@@ -343,6 +388,10 @@ void LLViewerShaderMgr::setShaders()
         return;
     }
 
+    mShaderList.clear();
+
+    LLShaderMgr::sMirrorsEnabled = LLPipeline::RenderMirrors;
+
     if (!gGLManager.mHasRequirements)
     {
         // Viewer will show 'hardware requirements' warning later
@@ -524,6 +573,8 @@ void LLViewerShaderMgr::setShaders()
     }
     gPipeline.createGLBuffers();
 
+    finalizeShaderList();
+
     reentrance = false;
 }
 
@@ -623,6 +674,16 @@ std::string LLViewerShaderMgr::loadBasicShaders()
 		attribs["REF_SAMPLE_COUNT"] = "32";
 	}
 
+    { // PBR terrain
+        const S32 mapping = clamp_terrain_mapping(gSavedSettings.getS32("RenderTerrainPBRPlanarSampleCount"));
+        attribs["TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT"] = llformat("%d", mapping);
+        const F32 triplanar_factor = gSavedSettings.getF32("RenderTerrainPBRTriplanarBlendFactor");
+        attribs["TERRAIN_TRIPLANAR_BLEND_FACTOR"] = llformat("%.2f", triplanar_factor);
+        S32 detail = gSavedSettings.getS32("RenderTerrainPBRDetail");
+        detail = llclamp(detail, TERRAIN_PBR_DETAIL_MIN, TERRAIN_PBR_DETAIL_MAX);
+        attribs["TERRAIN_PBR_DETAIL"] = llformat("%d", detail);
+    }
+
 	LLGLSLShader::sGlobalDefines = attribs;
 
 	// We no longer have to bind the shaders to global glhandles, they are automatically added to a map now.
@@ -658,8 +719,10 @@ std::string LLViewerShaderMgr::loadBasicShaders()
 	index_channels.push_back(-1);    shaders.push_back( make_pair( "environment/encodeNormF.glsl",	mShaderLevel[SHADER_ENVIRONMENT] ) );
 	index_channels.push_back(-1);    shaders.push_back( make_pair( "environment/srgbF.glsl",                    mShaderLevel[SHADER_ENVIRONMENT] ) );
 	index_channels.push_back(-1);    shaders.push_back( make_pair( "deferred/deferredUtil.glsl",                    1) );
+    index_channels.push_back(-1);    shaders.push_back( make_pair( "deferred/globalF.glsl",                          1));
 	index_channels.push_back(-1);    shaders.push_back( make_pair( "deferred/shadowUtil.glsl",                      1) );
 	index_channels.push_back(-1);    shaders.push_back( make_pair( "deferred/aoUtil.glsl",                          1) );
+	index_channels.push_back(-1);    shaders.push_back( make_pair( "deferred/pbrterrainUtilF.glsl",                 1) );
     index_channels.push_back(-1);    shaders.push_back( make_pair( "deferred/reflectionProbeF.glsl",                has_reflection_probes ? 3 : 2) );
     index_channels.push_back(-1);    shaders.push_back( make_pair( "deferred/screenSpaceReflUtil.glsl",             ssr ? 3 : 1) );
 	index_channels.push_back(-1);    shaders.push_back( make_pair( "lighting/lightNonIndexedF.glsl",                    mShaderLevel[SHADER_LIGHTING] ) );
@@ -951,6 +1014,7 @@ BOOL LLViewerShaderMgr::loadShadersDeferred()
         gDeferredSkinnedPBROpaqueProgram.unload();
         gDeferredPBRAlphaProgram.unload();
         gDeferredSkinnedPBRAlphaProgram.unload();
+		gDeferredPBRTerrainProgram.unload();
 
 		return TRUE;
 	}
@@ -1044,9 +1108,17 @@ BOOL LLViewerShaderMgr::loadShadersDeferred()
 	{
 		if (success)
 		{
-            mShaderList.push_back(&gDeferredMaterialProgram[i]);
+            bool has_skin = i & 0x10;
 
-			gDeferredMaterialProgram[i].mName = llformat("Deferred Material Shader %d", i);
+            if (!has_skin)
+            {
+                mShaderList.push_back(&gDeferredMaterialProgram[i]);
+                gDeferredMaterialProgram[i].mName = llformat("Material Shader %d", i);
+            }
+            else
+            {
+                gDeferredMaterialProgram[i].mName = llformat("Skinned Material Shader %d", i);
+            }
 			
 			U32 alpha_mode = i & 0x3;
 
@@ -1083,7 +1155,7 @@ BOOL LLViewerShaderMgr::loadShadersDeferred()
                 gDeferredMaterialProgram[i].addPermutation("HAS_SUN_SHADOW", "1");
             }
 
-            bool has_skin = i & 0x10;
+            
             gDeferredMaterialProgram[i].mFeatures.hasSrgb = true;
             gDeferredMaterialProgram[i].mFeatures.encodesNormal = true;
             gDeferredMaterialProgram[i].mFeatures.calculatesAtmospherics = true;
@@ -1242,6 +1314,34 @@ BOOL LLViewerShaderMgr::loadShadersDeferred()
         success = shader->createShader(NULL, NULL);
         llassert(success);
     }
+
+	if (success)
+	{
+        S32 detail = gSavedSettings.getS32("RenderTerrainPBRDetail");
+        detail = llclamp(detail, TERRAIN_PBR_DETAIL_MIN, TERRAIN_PBR_DETAIL_MAX);
+        const S32 mapping = clamp_terrain_mapping(gSavedSettings.getS32("RenderTerrainPBRPlanarSampleCount"));
+        gDeferredPBRTerrainProgram.mName = llformat("Deferred PBR Terrain Shader %d %s",
+                detail,
+                (mapping == 1 ? "flat" : "triplanar"));
+        gDeferredPBRTerrainProgram.mFeatures.encodesNormal = true;
+        gDeferredPBRTerrainProgram.mFeatures.hasSrgb = true;
+        gDeferredPBRTerrainProgram.mFeatures.isAlphaLighting = true;
+        gDeferredPBRTerrainProgram.mFeatures.disableTextureIndex = true; //hack to disable auto-setup of texture channels
+        gDeferredPBRTerrainProgram.mFeatures.calculatesAtmospherics = true;
+        gDeferredPBRTerrainProgram.mFeatures.hasAtmospherics = true;
+        gDeferredPBRTerrainProgram.mFeatures.hasGamma = true;
+        gDeferredPBRTerrainProgram.mFeatures.hasTransport = true;
+        gDeferredPBRTerrainProgram.mFeatures.isPBRTerrain = true;
+
+        gDeferredPBRTerrainProgram.mShaderFiles.clear();
+        gDeferredPBRTerrainProgram.mShaderFiles.push_back(make_pair("deferred/pbrterrainV.glsl", GL_VERTEX_SHADER));
+        gDeferredPBRTerrainProgram.mShaderFiles.push_back(make_pair("deferred/pbrterrainF.glsl", GL_FRAGMENT_SHADER));
+        gDeferredPBRTerrainProgram.mShaderLevel = mShaderLevel[SHADER_DEFERRED];
+        gDeferredPBRTerrainProgram.addPermutation("TERRAIN_PBR_DETAIL", llformat("%d", detail));
+        gDeferredPBRTerrainProgram.addPermutation("TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT", llformat("%d", mapping));
+        success = gDeferredPBRTerrainProgram.createShader(NULL, NULL);
+        llassert(success);
+	}
 	
 	if (success)
 	{
@@ -1955,8 +2055,6 @@ BOOL LLViewerShaderMgr::loadShadersDeferred()
 		gDeferredTerrainProgram.mName = "Deferred Terrain Shader";
 		gDeferredTerrainProgram.mFeatures.encodesNormal = true;
 		gDeferredTerrainProgram.mFeatures.hasSrgb = true;
-		gDeferredTerrainProgram.mFeatures.calculatesLighting = false;
-		gDeferredTerrainProgram.mFeatures.hasLighting = false;
 		gDeferredTerrainProgram.mFeatures.isAlphaLighting = true;
 		gDeferredTerrainProgram.mFeatures.disableTextureIndex = true; //hack to disable auto-setup of texture channels
 		gDeferredTerrainProgram.mFeatures.calculatesAtmospherics = true;
@@ -2643,6 +2741,33 @@ BOOL LLViewerShaderMgr::loadShadersInterface()
 
 	if (success)
 	{
+        for (S32 variant = 0; variant < NORMAL_DEBUG_SHADER_COUNT; ++variant)
+        {
+            LLGLSLShader& shader = gNormalDebugProgram[variant];
+            LLGLSLShader& skinned_shader = gSkinnedNormalDebugProgram[variant];
+            shader.mName = "Normal Debug Shader";
+            shader.mShaderFiles.clear();
+            shader.mShaderFiles.push_back(make_pair("interface/normaldebugV.glsl", GL_VERTEX_SHADER));
+            // *NOTE: Geometry shaders have a reputation for being slow.
+            // Consider using compute shaders instead, which have a reputation
+            // for being fast. This geometry shader in particular seems to run
+            // fine on my machine, but I won't vouch for this in
+            // performance-critical areas.  -Cosmic,2023-09-28
+            shader.mShaderFiles.push_back(make_pair("interface/normaldebugG.glsl", GL_GEOMETRY_SHADER));
+            shader.mShaderFiles.push_back(make_pair("interface/normaldebugF.glsl", GL_FRAGMENT_SHADER));
+            shader.mRiggedVariant = &skinned_shader;
+            shader.mShaderLevel = mShaderLevel[SHADER_INTERFACE];
+            if (variant == NORMAL_DEBUG_SHADER_WITH_TANGENTS)
+            {
+                shader.addPermutation("HAS_ATTRIBUTE_TANGENT", "1");
+            }
+            success = make_rigged_variant(shader, skinned_shader);
+            success = success && shader.createShader(NULL, NULL);
+        }
+	}
+
+	if (success)
+	{
 		gClipProgram.mName = "Clip Shader";
 		gClipProgram.mShaderFiles.clear();
 		gClipProgram.mShaderFiles.push_back(make_pair("interface/clipV.glsl", GL_VERTEX_SHADER));
@@ -2744,8 +2869,21 @@ BOOL LLViewerShaderMgr::loadShadersInterface()
         gRadianceGenProgram.mShaderFiles.push_back(make_pair("interface/radianceGenV.glsl", GL_VERTEX_SHADER));
         gRadianceGenProgram.mShaderFiles.push_back(make_pair("interface/radianceGenF.glsl", GL_FRAGMENT_SHADER));
         gRadianceGenProgram.mShaderLevel = mShaderLevel[SHADER_INTERFACE];
+        gRadianceGenProgram.addPermutation("PROBE_FILTER_SAMPLES", "32");
         success = gRadianceGenProgram.createShader(NULL, NULL);
     }
+	
+    if (success && gGLManager.mHasCubeMapArray)
+    {
+        gHeroRadianceGenProgram.mName = "Hero Radiance Gen Shader";
+        gHeroRadianceGenProgram.mShaderFiles.clear();
+        gHeroRadianceGenProgram.mShaderFiles.push_back(make_pair("interface/radianceGenV.glsl", GL_VERTEX_SHADER));
+        gHeroRadianceGenProgram.mShaderFiles.push_back(make_pair("interface/radianceGenF.glsl", GL_FRAGMENT_SHADER));
+        gHeroRadianceGenProgram.mShaderLevel = mShaderLevel[SHADER_INTERFACE];
+        gHeroRadianceGenProgram.addPermutation("HERO_PROBES", "1");
+        gHeroRadianceGenProgram.addPermutation("PROBE_FILTER_SAMPLES", "4");
+        success                              = gHeroRadianceGenProgram.createShader(NULL, NULL);
+    }
 
     if (success && gGLManager.mHasCubeMapArray)
     {
diff --git a/indra/newview/llviewershadermgr.h b/indra/newview/llviewershadermgr.h
index 04da7e48ae..57fc66ce0d 100644
--- a/indra/newview/llviewershadermgr.h
+++ b/indra/newview/llviewershadermgr.h
@@ -41,6 +41,10 @@ public:
 	LLViewerShaderMgr();
 	/* virtual */ ~LLViewerShaderMgr();
 
+    // Add shaders to mShaderList for later uniform propagation
+    // Will assert on redundant shader entries in debug builds
+    void finalizeShaderList();
+
 	// singleton pattern implementation
 	static LLViewerShaderMgr * instance();
 	static void releaseInstance();
@@ -153,9 +157,18 @@ extern LLGLSLShader			gGlowCombineProgram;
 extern LLGLSLShader			gReflectionMipProgram;
 extern LLGLSLShader         gGaussianProgram;
 extern LLGLSLShader         gRadianceGenProgram;
+extern LLGLSLShader         gHeroRadianceGenProgram;
 extern LLGLSLShader         gIrradianceGenProgram;
 extern LLGLSLShader			gGlowCombineFXAAProgram;
 extern LLGLSLShader			gDebugProgram;
+enum NormalDebugShaderVariant : S32
+{
+    NORMAL_DEBUG_SHADER_DEFAULT,
+    NORMAL_DEBUG_SHADER_WITH_TANGENTS,
+    NORMAL_DEBUG_SHADER_COUNT
+};
+extern LLGLSLShader			gNormalDebugProgram[NORMAL_DEBUG_SHADER_COUNT];
+extern LLGLSLShader			gSkinnedNormalDebugProgram[NORMAL_DEBUG_SHADER_COUNT];
 extern LLGLSLShader			gClipProgram;
 extern LLGLSLShader			gBenchmarkProgram;
 extern LLGLSLShader         gReflectionProbeDisplayProgram;
@@ -171,7 +184,6 @@ extern LLGLSLShader			gOneTextureFilterProgram;
 //object shaders
 extern LLGLSLShader		gObjectPreviewProgram;
 extern LLGLSLShader        gPhysicsPreviewProgram;
-extern LLGLSLShader        gSkinnedObjectFullbrightAlphaMaskProgram;
 extern LLGLSLShader		gObjectBumpProgram;
 extern LLGLSLShader        gSkinnedObjectBumpProgram;
 extern LLGLSLShader		gObjectAlphaMaskNoColorProgram;
@@ -272,4 +284,20 @@ extern LLGLSLShader         gPBRGlowProgram;
 extern LLGLSLShader         gDeferredPBROpaqueProgram;
 extern LLGLSLShader         gDeferredPBRAlphaProgram;
 extern LLGLSLShader         gHUDPBRAlphaProgram;
+
+// Encodes detail level for dropping textures, in accordance with the GLTF spec where possible
+// 0 is highest detail, -1 drops emissive, etc
+// Dropping metallic roughness is off-spec - Reserve for potato machines as needed
+// https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#additional-textures
+enum TerrainPBRDetail : S32
+{
+    TERRAIN_PBR_DETAIL_MAX                = 0,
+    TERRAIN_PBR_DETAIL_EMISSIVE           = 0,
+    TERRAIN_PBR_DETAIL_OCCLUSION          = -1,
+    TERRAIN_PBR_DETAIL_NORMAL             = -2,
+    TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS = -3,
+    TERRAIN_PBR_DETAIL_BASE_COLOR         = -4,
+    TERRAIN_PBR_DETAIL_MIN                = -4,
+};
+extern LLGLSLShader         gDeferredPBRTerrainProgram;
 #endif
diff --git a/indra/newview/llviewertexture.cpp b/indra/newview/llviewertexture.cpp
index 56bba51692..8436159e14 100644
--- a/indra/newview/llviewertexture.cpp
+++ b/indra/newview/llviewertexture.cpp
@@ -1699,7 +1699,7 @@ void LLViewerFetchedTexture::processTextureStats()
         {
             if (mFullWidth > MAX_IMAGE_SIZE_DEFAULT || mFullHeight > MAX_IMAGE_SIZE_DEFAULT)
             {
-                mDesiredDiscardLevel = 1; // MAX_IMAGE_SIZE_DEFAULT = 1024 and max size ever is 2048
+                mDesiredDiscardLevel = 1; // MAX_IMAGE_SIZE_DEFAULT = 2048 and max size ever is 4096
             }
             else
             {
@@ -1712,7 +1712,7 @@ void LLViewerFetchedTexture::processTextureStats()
 		}
 		else
 		{
-			U32 desired_size = MAX_IMAGE_SIZE_DEFAULT; // MAX_IMAGE_SIZE_DEFAULT = 1024 and max size ever is 2048
+			U32 desired_size = MAX_IMAGE_SIZE_DEFAULT; // MAX_IMAGE_SIZE_DEFAULT = 2048 and max size ever is 4096
 			if(!mKnownDrawWidth || !mKnownDrawHeight || mFullWidth <= mKnownDrawWidth || mFullHeight <= mKnownDrawHeight)
 			{
 				if (mFullWidth > desired_size || mFullHeight > desired_size)
@@ -3089,7 +3089,7 @@ void LLViewerLODTexture::processTextureStats()
 	{
 		mDesiredDiscardLevel = 0;
 		if (mFullWidth > MAX_IMAGE_SIZE_DEFAULT || mFullHeight > MAX_IMAGE_SIZE_DEFAULT)
-			mDesiredDiscardLevel = 1; // MAX_IMAGE_SIZE_DEFAULT = 1024 and max size ever is 2048
+			mDesiredDiscardLevel = 1; // MAX_IMAGE_SIZE_DEFAULT = 2048 and max size ever is 4096
 	}
 	else if (mBoostLevel < LLGLTexture::BOOST_HIGH && mMaxVirtualSize <= 10.f)
 	{
@@ -3134,7 +3134,7 @@ void LLViewerLODTexture::processTextureStats()
         discard_level = floorf(discard_level);
 
         F32 min_discard = 0.f;
-        U32 desired_size = MAX_IMAGE_SIZE_DEFAULT; // MAX_IMAGE_SIZE_DEFAULT = 1024 and max size ever is 2048
+        U32 desired_size = MAX_IMAGE_SIZE_DEFAULT; // MAX_IMAGE_SIZE_DEFAULT = 2048 and max size ever is 4096
         if (mBoostLevel <= LLGLTexture::BOOST_SCULPTED)
         {
             desired_size = DESIRED_NORMAL_TEXTURE_SIZE;
diff --git a/indra/newview/llviewerwindow.cpp b/indra/newview/llviewerwindow.cpp
index ed671fe849..0aae6f4b35 100644
--- a/indra/newview/llviewerwindow.cpp
+++ b/indra/newview/llviewerwindow.cpp
@@ -5307,7 +5307,7 @@ BOOL LLViewerWindow::simpleSnapshot(LLImageRaw* raw, S32 image_width, S32 image_
 
 void display_cube_face();
 
-BOOL LLViewerWindow::cubeSnapshot(const LLVector3& origin, LLCubeMapArray* cubearray, S32 cubeIndex, S32 face, F32 near_clip, bool dynamic_render)
+BOOL LLViewerWindow::cubeSnapshot(const LLVector3& origin, LLCubeMapArray* cubearray, S32 cubeIndex, S32 face, F32 near_clip, bool dynamic_render, bool useCustomClipPlane, LLPlane clipPlane)
 {
     // NOTE: implementation derived from LLFloater360Capture::capture360Images() and simpleSnapshot
     LL_PROFILE_ZONE_SCOPED_CATEGORY_APP;
@@ -5338,6 +5338,14 @@ BOOL LLViewerWindow::cubeSnapshot(const LLVector3& origin, LLCubeMapArray* cubea
     camera->setOrigin(origin);
     camera->setNear(near_clip);
 
+	LLPlane previousClipPlane;
+
+	if (useCustomClipPlane)
+	{
+        previousClipPlane = camera->getUserClipPlane();
+        camera->setUserClipPlane(clipPlane);
+	}
+
     glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); // stencil buffer is deprecated | GL_STENCIL_BUFFER_BIT);
     
     U32 dynamic_render_types[] = {
@@ -5444,6 +5452,11 @@ BOOL LLViewerWindow::cubeSnapshot(const LLVector3& origin, LLCubeMapArray* cubea
 
     gPipeline.resetDrawOrders();
     mWorldViewRectRaw = window_rect;
+
+	if (useCustomClipPlane)
+	{
+        camera->setUserClipPlane(previousClipPlane);
+	}
     
     // restore original view/camera/avatar settings settings
     *camera = saved_camera;
diff --git a/indra/newview/llviewerwindow.h b/indra/newview/llviewerwindow.h
index ccef006a07..ad634503ba 100644
--- a/indra/newview/llviewerwindow.h
+++ b/indra/newview/llviewerwindow.h
@@ -374,7 +374,8 @@ public:
     // index - cube index in the array to use (cube index, not face-layer)
     // face - which cube face to update
     // near_clip - near clip setting to use
-    BOOL cubeSnapshot(const LLVector3& origin, LLCubeMapArray* cubearray, S32 index, S32 face, F32 near_clip, bool render_avatars);
+    BOOL cubeSnapshot(const LLVector3 &origin, LLCubeMapArray *cubearray, S32 index, S32 face, F32 near_clip, bool render_avatars,
+                      bool customCullingPlane = false, LLPlane cullingPlane = LLPlane(LLVector3(0, 0, 0), LLVector3(0, 0, 1)));
 
     
     // special implementation of simpleSnapshot for reflection maps
diff --git a/indra/newview/llvlcomposition.cpp b/indra/newview/llvlcomposition.cpp
index 001fab7755..c092eb82f3 100644
--- a/indra/newview/llvlcomposition.cpp
+++ b/indra/newview/llvlcomposition.cpp
@@ -34,12 +34,16 @@
 #include "lltextureview.h"
 #include "llviewertexture.h"
 #include "llviewertexturelist.h"
+#include "llfetchedgltfmaterial.h"
+#include "llgltfmateriallist.h"
 #include "llviewerregion.h"
 #include "noise.h"
 #include "llregionhandle.h" // for from_region_handle
 #include "llviewercontrol.h"
 
 
+static const U32 BASE_SIZE = 128;
+
 
 F32 bilinear(const F32 v00, const F32 v01, const F32 v10, const F32 v11, const F32 x_frac, const F32 y_frac)
 {
@@ -57,18 +61,245 @@ F32 bilinear(const F32 v00, const F32 v01, const F32 v10, const F32 v11, const F
 	return result;
 }
 
+LLTerrainMaterials::LLTerrainMaterials()
+{
+    for (S32 i = 0; i < ASSET_COUNT; ++i)
+    {
+        mMaterialTexturesSet[i] = false;
+    }
+}
 
-LLVLComposition::LLVLComposition(LLSurface *surfacep, const U32 width, const F32 scale) :
-	LLViewerLayer(width, scale),
-	mParamsReady(FALSE)
+LLTerrainMaterials::~LLTerrainMaterials()
 {
-	mSurfacep = surfacep;
+}
+
+BOOL LLTerrainMaterials::generateMaterials()
+{
+    if (texturesReady(true, true))
+    {
+        return TRUE;
+    }
+
+    if (materialsReady(true, true))
+    {
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+LLUUID LLTerrainMaterials::getDetailAssetID(S32 asset)
+{
+    llassert(mDetailTextures[asset] && mDetailMaterials[asset]);
+    // *HACK: Assume both the the material and texture were fetched in the same
+    // way using the same UUID. However, we may not know at this point which
+    // one will load.
+	return mDetailTextures[asset]->getID();
+}
+
+LLPointer<LLViewerFetchedTexture> fetch_terrain_texture(const LLUUID& id)
+{
+    if (id.isNull())
+    {
+        return nullptr;
+    }
+
+    LLPointer<LLViewerFetchedTexture> tex = LLViewerTextureManager::getFetchedTexture(id);
+    tex->setNoDelete();
+    return tex;
+}
+
+void LLTerrainMaterials::setDetailAssetID(S32 asset, const LLUUID& id)
+{
+	// This is terrain texture, but we are not setting it as BOOST_TERRAIN
+	// since we will be manipulating it later as needed.
+	mDetailTextures[asset] = fetch_terrain_texture(id);
+    LLPointer<LLFetchedGLTFMaterial>& mat = mDetailMaterials[asset];
+    mat = id.isNull() ? nullptr : gGLTFMaterialList.getMaterial(id);
+    mMaterialTexturesSet[asset] = false;
+}
+
+LLTerrainMaterials::Type LLTerrainMaterials::getMaterialType()
+{
+	LL_PROFILE_ZONE_SCOPED;
+
+    const BOOL use_textures = texturesReady(false, false) || !materialsReady(false, false);
+    return use_textures ? Type::TEXTURE : Type::PBR;
+}
+
+bool LLTerrainMaterials::texturesReady(bool boost, bool strict)
+{
+    bool ready[ASSET_COUNT];
+    // *NOTE: Calls to textureReady may boost textures. Do not early-return.
+    for (S32 i = 0; i < ASSET_COUNT; i++)
+    {
+        ready[i] = textureReady(mDetailTextures[i], boost);
+    }
+
+    bool one_ready = false;
+    for (S32 i = 0; i < ASSET_COUNT; i++)
+    {
+        const bool current_ready = ready[i];
+        one_ready = one_ready || current_ready;
+        if (!current_ready && strict)
+        {
+            return false;
+        }
+    }
+    return one_ready;
+}
+
+bool LLTerrainMaterials::materialsReady(bool boost, bool strict)
+{
+    bool ready[ASSET_COUNT];
+    // *NOTE: Calls to materialReady may boost materials/textures. Do not early-return.
+    for (S32 i = 0; i < ASSET_COUNT; i++)
+    {
+        ready[i] = materialReady(mDetailMaterials[i], mMaterialTexturesSet[i], boost, strict);
+    }
+
+#if 1
+    static bool sRenderTerrainPBREnabled = gSavedSettings.get<bool>("RenderTerrainPBREnabled");
+    static LLCachedControl<bool> sRenderTerrainPBRForce(gSavedSettings, "RenderTerrainPBRForce", false);
+    if (sRenderTerrainPBREnabled && sRenderTerrainPBRForce)
+    {
+        bool defined = true;
+        for (S32 i = 0; i < ASSET_COUNT; i++)
+        {
+            if (!mDetailMaterials[i])
+            {
+                defined = false;
+                break;
+            }
+        }
+        if (defined)
+        {
+            return true;
+        }
+    }
+#endif
+
+    bool one_ready = false;
+    for (S32 i = 0; i < ASSET_COUNT; i++)
+    {
+        const bool current_ready = ready[i];
+        one_ready = one_ready || current_ready;
+        if (!current_ready && strict)
+        {
+            return false;
+        }
+    }
+    return one_ready;
+}
 
+// Boost the texture loading priority
+// Return true when ready to use (i.e. texture is sufficiently loaded)
+// static
+bool LLTerrainMaterials::textureReady(LLPointer<LLViewerFetchedTexture>& tex, bool boost)
+{
+    llassert(tex);
+    if (!tex) { return false; }
+
+    if (tex->getDiscardLevel() < 0)
+    {
+        if (boost)
+        {
+            tex->setBoostLevel(LLGLTexture::BOOST_TERRAIN); // in case we are at low detail
+            tex->addTextureStats(BASE_SIZE*BASE_SIZE);
+        }
+        return false;
+    }
+    if ((tex->getDiscardLevel() != 0 &&
+         (tex->getWidth() < BASE_SIZE ||
+          tex->getHeight() < BASE_SIZE)))
+    {
+        if (boost)
+        {
+            S32 width = tex->getFullWidth();
+            S32 height = tex->getFullHeight();
+            S32 min_dim = llmin(width, height);
+            S32 ddiscard = 0;
+            while (min_dim > BASE_SIZE && ddiscard < MAX_DISCARD_LEVEL)
+            {
+                ddiscard++;
+                min_dim /= 2;
+            }
+            tex->setBoostLevel(LLGLTexture::BOOST_TERRAIN); // in case we are at low detail
+            tex->setMinDiscardLevel(ddiscard);
+            tex->addTextureStats(BASE_SIZE*BASE_SIZE); // priority
+        }
+        return false;
+    }
+    if (tex->getComponents() == 0)
+    {
+        return false;
+    }
+    return true;
+}
+
+// Boost the loading priority of every known texture in the material
+// Return true when ready to use
+// static
+bool LLTerrainMaterials::materialReady(LLPointer<LLFetchedGLTFMaterial> &mat, bool &textures_set, bool boost, bool strict)
+{
+    if (!mat || !mat->isLoaded())
+    {
+        return false;
+    }
+
+    // Material is loaded, but textures may not be
+    if (!textures_set)
+    {
+        // *NOTE: These can sometimes be set to to nullptr due to
+        // updateTEMaterialTextures. For the sake of robustness, we emulate
+        // that fetching behavior by setting textures of null IDs to nullptr.
+        mat->mBaseColorTexture         = fetch_terrain_texture(mat->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_BASE_COLOR]);
+        mat->mNormalTexture            = fetch_terrain_texture(mat->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_NORMAL]);
+        mat->mMetallicRoughnessTexture = fetch_terrain_texture(mat->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_METALLIC_ROUGHNESS]);
+        mat->mEmissiveTexture          = fetch_terrain_texture(mat->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_EMISSIVE]);
+        textures_set                   = true;
+
+        return false;
+    }
+
+    // *NOTE: Calls to textureReady may boost textures. Do not early-return.
+    bool ready[LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT];
+    ready[LLGLTFMaterial::GLTF_TEXTURE_INFO_BASE_COLOR] =
+        mat->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_BASE_COLOR].isNull() || textureReady(mat->mBaseColorTexture, boost);
+    ready[LLGLTFMaterial::GLTF_TEXTURE_INFO_NORMAL] =
+        mat->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_NORMAL].isNull() || textureReady(mat->mNormalTexture, boost);
+    ready[LLGLTFMaterial::GLTF_TEXTURE_INFO_METALLIC_ROUGHNESS] =
+        mat->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_METALLIC_ROUGHNESS].isNull() ||
+        textureReady(mat->mMetallicRoughnessTexture, boost);
+    ready[LLGLTFMaterial::GLTF_TEXTURE_INFO_EMISSIVE] =
+        mat->mTextureId[LLGLTFMaterial::GLTF_TEXTURE_INFO_EMISSIVE].isNull() || textureReady(mat->mEmissiveTexture, boost);
+
+    if (strict)
+    {
+        for (U32 i = 0; i < LLGLTFMaterial::GLTF_TEXTURE_INFO_COUNT; ++i)
+        {
+            if (!ready[i])
+            {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+
+LLVLComposition::LLVLComposition(LLSurface *surfacep, const U32 width, const F32 scale) :
+    LLTerrainMaterials(),
+	LLViewerLayer(width, scale)
+{
 	// Load Terrain Textures - Original ones
-	setDetailTextureID(0, TERRAIN_DIRT_DETAIL);
-	setDetailTextureID(1, TERRAIN_GRASS_DETAIL);
-	setDetailTextureID(2, TERRAIN_MOUNTAIN_DETAIL);
-	setDetailTextureID(3, TERRAIN_ROCK_DETAIL);
+	setDetailAssetID(0, TERRAIN_DIRT_DETAIL);
+	setDetailAssetID(1, TERRAIN_GRASS_DETAIL);
+	setDetailAssetID(2, TERRAIN_MOUNTAIN_DETAIL);
+	setDetailAssetID(3, TERRAIN_ROCK_DETAIL);
+
+	mSurfacep = surfacep;
 
 	// Initialize the texture matrix to defaults.
 	for (S32 i = 0; i < CORNER_COUNT; ++i)
@@ -76,14 +307,12 @@ LLVLComposition::LLVLComposition(LLSurface *surfacep, const U32 width, const F32
 		mStartHeight[i] = gSavedSettings.getF32("TerrainColorStartHeight");
 		mHeightRange[i] = gSavedSettings.getF32("TerrainColorHeightRange");
 	}
-	mTexScaleX = 16.f;
-	mTexScaleY = 16.f;
-	mTexturesLoaded = FALSE;
 }
 
 
 LLVLComposition::~LLVLComposition()
 {
+    LLTerrainMaterials::~LLTerrainMaterials();
 }
 
 
@@ -92,20 +321,6 @@ void LLVLComposition::setSurface(LLSurface *surfacep)
 	mSurfacep = surfacep;
 }
 
-
-void LLVLComposition::setDetailTextureID(S32 corner, const LLUUID& id)
-{
-	if(id.isNull())
-	{
-		return;
-	}
-	// This is terrain texture, but we are not setting it as BOOST_TERRAIN
-	// since we will be manipulating it later as needed.
-	mDetailTextures[corner] = LLViewerTextureManager::getFetchedTexture(id);
-	mDetailTextures[corner]->setNoDelete() ;
-	mRawImages[corner] = NULL;
-}
-
 BOOL LLVLComposition::generateHeights(const F32 x, const F32 y,
 									  const F32 width, const F32 height)
 {
@@ -149,10 +364,6 @@ BOOL LLVLComposition::generateHeights(const F32 x, const F32 y,
 	const F32 noise_magnitude = 2.f;		//  Degree to which noise modulates composition layer (versus
 											//  simple height)
 
-	// Heights map into textures as 0-1 = first, 1-2 = second, etc.
-	// So we need to compress heights into this range.
-	const S32 NUM_TEXTURES = 4;
-
 	const F32 xyScaleInv = (1.f / xyScale);
 	const F32 zScaleInv = (1.f / zScale);
 
@@ -199,7 +410,7 @@ BOOL LLVLComposition::generateHeights(const F32 x, const F32 y,
 			twiddle += turbulence2(vec, 2)*slope_squared;	//  High frequency component
 			twiddle *= noise_magnitude;
 
-			F32 scaled_noisy_height = (height + twiddle - start_height) * F32(NUM_TEXTURES) / height_range;
+			F32 scaled_noisy_height = (height + twiddle - start_height) * F32(ASSET_COUNT) / height_range;
 
 			scaled_noisy_height = llmax(0.f, scaled_noisy_height);
 			scaled_noisy_height = llmin(3.f, scaled_noisy_height);
@@ -209,49 +420,20 @@ BOOL LLVLComposition::generateHeights(const F32 x, const F32 y,
 	return TRUE;
 }
 
-static const U32 BASE_SIZE = 128;
+LLTerrainMaterials gLocalTerrainMaterials;
 
 BOOL LLVLComposition::generateComposition()
 {
-
 	if (!mParamsReady)
 	{
 		// All the parameters haven't been set yet (we haven't gotten the message from the sim)
 		return FALSE;
 	}
 
-	for (S32 i = 0; i < 4; i++)
-	{
-		if (mDetailTextures[i]->getDiscardLevel() < 0)
-		{
-			mDetailTextures[i]->setBoostLevel(LLGLTexture::BOOST_TERRAIN); // in case we are at low detail
-			mDetailTextures[i]->addTextureStats(BASE_SIZE*BASE_SIZE);
-			return FALSE;
-		}
-		if ((mDetailTextures[i]->getDiscardLevel() != 0 &&
-			 (mDetailTextures[i]->getWidth() < BASE_SIZE ||
-			  mDetailTextures[i]->getHeight() < BASE_SIZE)))
-		{
-			S32 width = mDetailTextures[i]->getFullWidth();
-			S32 height = mDetailTextures[i]->getFullHeight();
-			S32 min_dim = llmin(width, height);
-			S32 ddiscard = 0;
-			while (min_dim > BASE_SIZE && ddiscard < MAX_DISCARD_LEVEL)
-			{
-				ddiscard++;
-				min_dim /= 2;
-			}
-			mDetailTextures[i]->setBoostLevel(LLGLTexture::BOOST_TERRAIN); // in case we are at low detail
-			mDetailTextures[i]->setMinDiscardLevel(ddiscard);
-			mDetailTextures[i]->addTextureStats(BASE_SIZE*BASE_SIZE); // priority
-			return FALSE;
-		}
-	}
-	
-	return TRUE;
+    return LLTerrainMaterials::generateMaterials();
 }
 
-BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
+BOOL LLVLComposition::generateMinimapTileLand(const F32 x, const F32 y,
 									  const F32 width, const F32 height)
 {
 	LL_PROFILE_ZONE_SCOPED
@@ -259,8 +441,6 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
 	llassert(x >= 0.f);
 	llassert(y >= 0.f);
 
-	LLTimer gen_timer;
-
 	///////////////////////////
 	//
 	// Generate raw data arrays for surface textures
@@ -268,15 +448,58 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
 	//
 
 	// These have already been validated by generateComposition.
-	U8* st_data[4];
-	S32 st_data_size[4]; // for debugging
-
-	for (S32 i = 0; i < 4; i++)
+	U8* st_data[ASSET_COUNT];
+	S32 st_data_size[ASSET_COUNT]; // for debugging
+
+    const bool use_textures = getMaterialType() != LLTerrainMaterials::Type::PBR;
+    if (use_textures)
+    {
+        if (!texturesReady(true, true)) { return FALSE; }
+    }
+    else
+    {
+        if (!materialsReady(true, true)) { return FALSE; }
+    }
+
+	for (S32 i = 0; i < ASSET_COUNT; i++)
 	{
 		if (mRawImages[i].isNull())
 		{
 			// Read back a raw image for this discard level, if it exists
-			S32 min_dim = llmin(mDetailTextures[i]->getFullWidth(), mDetailTextures[i]->getFullHeight());
+            LLViewerFetchedTexture* tex;
+            LLViewerFetchedTexture* tex_emissive; // Can be null
+            bool has_base_color_factor;
+            bool has_emissive_factor;
+            LLColor3 base_color_factor;
+            LLColor3 emissive_factor;
+            if (use_textures)
+            {
+                tex = mDetailTextures[i];
+                tex_emissive = nullptr;
+                has_base_color_factor = false;
+                has_emissive_factor = false;
+                llassert(tex);
+            }
+            else
+            {
+                tex = mDetailMaterials[i]->mBaseColorTexture;
+                tex_emissive = mDetailMaterials[i]->mEmissiveTexture;
+                base_color_factor = LLColor3(mDetailMaterials[i]->mBaseColor);
+                // *HACK: Treat alpha as black
+                base_color_factor *= (mDetailMaterials[i]->mBaseColor.mV[VW]);
+                emissive_factor = mDetailMaterials[i]->mEmissiveColor;
+                has_base_color_factor = (base_color_factor.mV[VX] != 1.f ||
+                                         base_color_factor.mV[VY] != 1.f ||
+                                         base_color_factor.mV[VZ] != 1.f);
+                has_emissive_factor = (emissive_factor.mV[VX] != 1.f ||
+                                       emissive_factor.mV[VY] != 1.f ||
+                                       emissive_factor.mV[VZ] != 1.f);
+            }
+
+            if (!tex) { tex = LLViewerFetchedTexture::sWhiteImagep; }
+            // tex_emissive can be null, and then will be ignored
+
+			S32 min_dim = llmin(tex->getFullWidth(), tex->getFullHeight());
 			S32 ddiscard = 0;
 			while (min_dim > BASE_SIZE && ddiscard < MAX_DISCARD_LEVEL)
 			{
@@ -284,34 +507,92 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
 				min_dim /= 2;
 			}
 
-			BOOL delete_raw = (mDetailTextures[i]->reloadRawImage(ddiscard) != NULL) ;
-			if(mDetailTextures[i]->getRawImageLevel() != ddiscard)//raw iamge is not ready, will enter here again later.
+			BOOL delete_raw = (tex->reloadRawImage(ddiscard) != NULL) ;
+			if(tex->getRawImageLevel() != ddiscard)
 			{
-                if (mDetailTextures[i]->getFetchPriority() <= 0.0f && !mDetailTextures[i]->hasSavedRawImage())
+                // Raw image is not ready, will enter here again later.
+                if (tex->getFetchPriority() <= 0.0f && !tex->hasSavedRawImage())
                 {
-                    mDetailTextures[i]->setBoostLevel(LLGLTexture::BOOST_MAP);
-                    mDetailTextures[i]->forceToRefetchTexture(ddiscard);
+                    tex->setBoostLevel(LLGLTexture::BOOST_MAP);
+                    tex->forceToRefetchTexture(ddiscard);
                 }
 
 				if(delete_raw)
 				{
-					mDetailTextures[i]->destroyRawImage() ;
+					tex->destroyRawImage() ;
 				}
-				LL_DEBUGS("Terrain") << "cached raw data for terrain detail texture is not ready yet: " << mDetailTextures[i]->getID() << " Discard: " << ddiscard << LL_ENDL;
 				return FALSE;
 			}
+            if (tex_emissive)
+            {
+                if(tex_emissive->getRawImageLevel() != ddiscard)
+                {
+                    // Raw image is not ready, will enter here again later.
+                    if (tex_emissive->getFetchPriority() <= 0.0f && !tex_emissive->hasSavedRawImage())
+                    {
+                        tex_emissive->setBoostLevel(LLGLTexture::BOOST_MAP);
+                        tex_emissive->forceToRefetchTexture(ddiscard);
+                    }
+
+                    if(delete_raw)
+                    {
+                        tex_emissive->destroyRawImage() ;
+                    }
+                    return FALSE;
+                }
+            }
 
-			mRawImages[i] = mDetailTextures[i]->getRawImage() ;
+			mRawImages[i] = tex->getRawImage() ;
 			if(delete_raw)
 			{
-				mDetailTextures[i]->destroyRawImage() ;
+				tex->destroyRawImage() ;
 			}
-			if (mDetailTextures[i]->getWidth(ddiscard) != BASE_SIZE ||
-				mDetailTextures[i]->getHeight(ddiscard) != BASE_SIZE ||
-				mDetailTextures[i]->getComponents() != 3)
+
+            // *TODO: This isn't quite right for PBR:
+            // 1) It does not convert the color images from SRGB to linear
+            // before mixing (which will always require copying the image).
+            // 2) It mixes emissive and base color before mixing terrain
+            // materials, but it should be the other way around
+            // 3) The composite function used to put emissive into base color
+            // is not an alpha blend.
+            // Long-term, we should consider a method that is more
+            // maintainable. Shaders, perhaps? Bake shaders to textures?
+            LLPointer<LLImageRaw> raw_emissive;
+            if (tex_emissive)
+            {
+                raw_emissive = tex_emissive->getRawImage();
+                if (has_emissive_factor ||
+                    tex_emissive->getWidth(ddiscard) != BASE_SIZE ||
+                    tex_emissive->getHeight(ddiscard) != BASE_SIZE ||
+                    tex_emissive->getComponents() != 4)
+                {
+                    LLPointer<LLImageRaw> newraw_emissive = new LLImageRaw(BASE_SIZE, BASE_SIZE, 4);
+                    // Copy RGB, leave alpha alone (set to opaque by default)
+                    newraw_emissive->copy(mRawImages[i]);
+                    if (has_emissive_factor)
+                    {
+                        newraw_emissive->tint(emissive_factor);
+                    }
+                    raw_emissive = newraw_emissive; // deletes old
+                }
+            }
+			if (has_base_color_factor ||
+                raw_emissive ||
+                tex->getWidth(ddiscard) != BASE_SIZE ||
+				tex->getHeight(ddiscard) != BASE_SIZE ||
+				tex->getComponents() != 3)
 			{
 				LLPointer<LLImageRaw> newraw = new LLImageRaw(BASE_SIZE, BASE_SIZE, 3);
 				newraw->composite(mRawImages[i]);
+                if (has_base_color_factor)
+                {
+                    newraw->tint(base_color_factor);
+                }
+                // Apply emissive texture
+                if (raw_emissive)
+                {
+                    newraw->composite(raw_emissive);
+                }
 				mRawImages[i] = newraw; // deletes old
 			}
 		}
@@ -333,12 +614,12 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
 
 	if (x_end > mWidth)
 	{
-		LL_WARNS("Terrain") << "x end > width" << LL_ENDL;
+        llassert(false);
 		x_end = mWidth;
 	}
 	if (y_end > mWidth)
 	{
-		LL_WARNS("Terrain") << "y end > width" << LL_ENDL;
+        llassert(false);
 		y_end = mWidth;
 	}
 
@@ -368,7 +649,7 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
 	
 	if (tex_comps != st_comps)
 	{
-		LL_WARNS("Terrain") << "Base texture comps != input texture comps" << LL_ENDL;
+        llassert(false);
 		return FALSE;
 	}
 
@@ -459,7 +740,7 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
 	}
 	texturep->setSubImage(raw, tex_x_begin, tex_y_begin, tex_x_end - tex_x_begin, tex_y_end - tex_y_begin);
 
-	for (S32 i = 0; i < 4; i++)
+	for (S32 i = 0; i < ASSET_COUNT; i++)
 	{
 		// Un-boost detatil textures (will get re-boosted if rendering in high detail)
 		mDetailTextures[i]->setBoostLevel(LLGLTexture::BOOST_NONE);
@@ -469,19 +750,19 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
 	return TRUE;
 }
 
-LLUUID LLVLComposition::getDetailTextureID(S32 corner)
-{
-	return mDetailTextures[corner]->getID();
-}
-
-LLViewerFetchedTexture* LLVLComposition::getDetailTexture(S32 corner)
+F32 LLVLComposition::getStartHeight(S32 corner)
 {
-	return mDetailTextures[corner];
+	return mStartHeight[corner];
 }
 
-F32 LLVLComposition::getStartHeight(S32 corner)
+void LLVLComposition::setDetailAssetID(S32 asset, const LLUUID& id)
 {
-	return mStartHeight[corner];
+	if (id.isNull())
+	{
+        return;
+    }
+    LLTerrainMaterials::setDetailAssetID(asset, id);
+	mRawImages[asset] = NULL;
 }
 
 void LLVLComposition::setStartHeight(S32 corner, const F32 start_height)
diff --git a/indra/newview/llvlcomposition.h b/indra/newview/llvlcomposition.h
index 2dd04ac5a5..73bfca6ed4 100644
--- a/indra/newview/llvlcomposition.h
+++ b/indra/newview/llvlcomposition.h
@@ -28,11 +28,58 @@
 #define LL_LLVLCOMPOSITION_H
 
 #include "llviewerlayer.h"
-#include "llviewertexture.h"
+#include "llpointer.h"
+
+#include "llimage.h"
 
 class LLSurface;
 
-class LLVLComposition : public LLViewerLayer
+class LLViewerFetchedTexture;
+class LLFetchedGLTFMaterial;
+
+class LLTerrainMaterials
+{
+public:
+	friend class LLDrawPoolTerrain;
+
+    LLTerrainMaterials();
+    virtual ~LLTerrainMaterials();
+
+	// Heights map into textures (or materials) as 0-1 = first, 1-2 = second, etc.
+	// So we need to compress heights into this range.
+    static const S32 ASSET_COUNT = 4;
+
+    enum class Type
+    {
+        TEXTURE,
+        PBR,
+        COUNT
+    };
+
+    BOOL generateMaterials();
+
+	LLUUID getDetailAssetID(S32 asset);
+	virtual void setDetailAssetID(S32 asset, const LLUUID& id);
+    Type getMaterialType();
+    bool texturesReady(bool boost, bool strict);
+    // strict = true -> all materials must be sufficiently loaded
+    // strict = false -> at least one material must be loaded
+    bool materialsReady(bool boost, bool strict);
+
+protected:
+    static bool textureReady(LLPointer<LLViewerFetchedTexture>& tex, bool boost);
+    // strict = true -> all materials must be sufficiently loaded
+    // strict = false -> at least one material must be loaded
+    static bool materialReady(LLPointer<LLFetchedGLTFMaterial>& mat, bool& textures_set, bool boost, bool strict);
+	LLPointer<LLViewerFetchedTexture> mDetailTextures[ASSET_COUNT];
+	LLPointer<LLFetchedGLTFMaterial> mDetailMaterials[ASSET_COUNT];
+    bool mMaterialTexturesSet[ASSET_COUNT];
+};
+
+// Local materials to override all regions
+extern LLTerrainMaterials gLocalTerrainMaterials;
+
+class LLVLComposition : public LLTerrainMaterials, public LLViewerLayer
 {
 public:
 	LLVLComposition(LLSurface *surfacep, const U32 width, const F32 scale);
@@ -44,7 +91,11 @@ public:
 	BOOL generateHeights(const F32 x, const F32 y, const F32 width, const F32 height);
 	BOOL generateComposition();
 	// Generate texture from composition values.
-	BOOL generateTexture(const F32 x, const F32 y, const F32 width, const F32 height);		
+	BOOL generateMinimapTileLand(const F32 x, const F32 y, const F32 width, const F32 height);		
+
+	// Heights map into textures (or materials) as 0-1 = first, 1-2 = second, etc.
+	// So we need to compress heights into this range.
+    static const S32 ASSET_COUNT = 4;
 
 	// Use these as indeces ito the get/setters below that use 'corner'
 	enum ECorner
@@ -55,12 +106,11 @@ public:
 		NORTHEAST = 3,
 		CORNER_COUNT = 4
 	};
-	LLUUID getDetailTextureID(S32 corner);
-	LLViewerFetchedTexture* getDetailTexture(S32 corner);
+
+	void setDetailAssetID(S32 asset, const LLUUID& id) override;
 	F32 getStartHeight(S32 corner);
 	F32 getHeightRange(S32 corner);
 
-	void setDetailTextureID(S32 corner, const LLUUID& id);
 	void setStartHeight(S32 corner, F32 start_height);
 	void setHeightRange(S32 corner, F32 range);
 
@@ -68,19 +118,21 @@ public:
 	friend class LLDrawPoolTerrain;
 	void setParamsReady()		{ mParamsReady = TRUE; }
 	BOOL getParamsReady() const	{ return mParamsReady; }
+
 protected:
-	BOOL mParamsReady;
+    static bool textureReady(LLPointer<LLViewerFetchedTexture>& tex, bool boost = false);
+    static bool materialReady(LLPointer<LLFetchedGLTFMaterial>& mat, bool& textures_set, bool boost = false);
+
+	BOOL mParamsReady = FALSE;
 	LLSurface *mSurfacep;
-	BOOL mTexturesLoaded;
 
-	LLPointer<LLViewerFetchedTexture> mDetailTextures[CORNER_COUNT];
-	LLPointer<LLImageRaw> mRawImages[CORNER_COUNT];
+	LLPointer<LLImageRaw> mRawImages[LLTerrainMaterials::ASSET_COUNT];
 
 	F32 mStartHeight[CORNER_COUNT];
 	F32 mHeightRange[CORNER_COUNT];
 
-	F32 mTexScaleX;
-	F32 mTexScaleY;
+	F32 mTexScaleX = 16.f;
+	F32 mTexScaleY = 16.f;
 };
 
 #endif //LL_LLVLCOMPOSITION_H
diff --git a/indra/newview/llvosurfacepatch.cpp b/indra/newview/llvosurfacepatch.cpp
index 15fabf0414..69b9476d38 100644
--- a/indra/newview/llvosurfacepatch.cpp
+++ b/indra/newview/llvosurfacepatch.cpp
@@ -39,6 +39,7 @@
 #include "llviewerobjectlist.h"
 #include "llviewerregion.h"
 #include "llvlcomposition.h"
+#include "llvolume.h"
 #include "llvovolume.h"
 #include "pipeline.h"
 #include "llspatialpartition.h"
@@ -213,6 +214,7 @@ BOOL LLVOSurfacePatch::updateGeometry(LLDrawable *drawable)
 
 void LLVOSurfacePatch::updateFaceSize(S32 idx)
 {
+    LL_PROFILE_ZONE_SCOPED;
 	if (idx != 0)
 	{
 		LL_WARNS() << "Terrain partition requested invalid face!!!" << LL_ENDL;
@@ -241,48 +243,50 @@ BOOL LLVOSurfacePatch::updateLOD()
 	return TRUE;
 }
 
-void LLVOSurfacePatch::getGeometry(LLStrider<LLVector3> &verticesp,
-								LLStrider<LLVector3> &normalsp,
-								LLStrider<LLVector2> &texCoords0p,
-								LLStrider<LLVector2> &texCoords1p,
-								LLStrider<U16> &indicesp)
+void LLVOSurfacePatch::getTerrainGeometry(LLStrider<LLVector3> &verticesp,
+                                              LLStrider<LLVector3> &normalsp,
+                                              LLStrider<LLVector2> &texCoords0p,
+                                              LLStrider<LLVector2> &texCoords1p,
+                                              LLStrider<U16> &indicesp)
 {
 	LLFace* facep = mDrawable->getFace(0);
-	if (facep)
-	{
-		U32 index_offset = facep->getGeomIndex();
-
-		updateMainGeometry(facep, 
-						verticesp,
-						normalsp,
-						texCoords0p,
-						texCoords1p,
-						indicesp,
-						index_offset);
-		updateNorthGeometry(facep, 
-							verticesp,
-							normalsp,
-							texCoords0p,
-							texCoords1p,
-							indicesp,
-							index_offset);
-		updateEastGeometry(facep, 
-							verticesp,
-							normalsp,
-							texCoords0p,
-							texCoords1p,
-							indicesp,
-							index_offset);
-	}
+    if (!facep)
+    {
+        return;
+    }
+
+    U32 index_offset = facep->getGeomIndex();
+
+    updateMainGeometry(facep, 
+                    verticesp,
+                    normalsp,
+                    texCoords0p,
+                    texCoords1p,
+                    indicesp,
+                    index_offset);
+    updateNorthGeometry(facep, 
+                        verticesp,
+                        normalsp,
+                        texCoords0p,
+                        texCoords1p,
+                        indicesp,
+                        index_offset);
+    updateEastGeometry(facep, 
+                        verticesp,
+                        normalsp,
+                        texCoords0p,
+                        texCoords1p,
+                        indicesp,
+                        index_offset);
 }
 
 void LLVOSurfacePatch::updateMainGeometry(LLFace *facep,
-										LLStrider<LLVector3> &verticesp,
-										LLStrider<LLVector3> &normalsp,
-										LLStrider<LLVector2> &texCoords0p,
-										LLStrider<LLVector2> &texCoords1p,
-										LLStrider<U16> &indicesp,
-										U32 &index_offset)
+                                        LLStrider<LLVector3> &verticesp,
+                                        LLStrider<LLVector3> &normalsp,
+                                        LLStrider<LLVector2> &texCoords0p,
+                                        LLStrider<LLVector2> &texCoords1p,
+                                        LLStrider<U16> &indicesp,
+                                        U32 &index_offset)
 {
 	S32 i, j, x, y;
 
@@ -381,12 +385,12 @@ void LLVOSurfacePatch::updateMainGeometry(LLFace *facep,
 
 
 void LLVOSurfacePatch::updateNorthGeometry(LLFace *facep,
-										LLStrider<LLVector3> &verticesp,
-										LLStrider<LLVector3> &normalsp,
-										LLStrider<LLVector2> &texCoords0p,
-										LLStrider<LLVector2> &texCoords1p,
-										LLStrider<U16> &indicesp,
-										U32 &index_offset)
+                                        LLStrider<LLVector3> &verticesp,
+                                        LLStrider<LLVector3> &normalsp,
+                                        LLStrider<LLVector2> &texCoords0p,
+                                        LLStrider<LLVector2> &texCoords1p,
+                                        LLStrider<U16> &indicesp,
+                                        U32 &index_offset)
 {
 	S32 i, x, y;
 
@@ -571,12 +575,12 @@ void LLVOSurfacePatch::updateNorthGeometry(LLFace *facep,
 }
 
 void LLVOSurfacePatch::updateEastGeometry(LLFace *facep,
-										  LLStrider<LLVector3> &verticesp,
-										  LLStrider<LLVector3> &normalsp,
-										  LLStrider<LLVector2> &texCoords0p,
-										  LLStrider<LLVector2> &texCoords1p,
-										  LLStrider<U16> &indicesp,
-										  U32 &index_offset)
+                                          LLStrider<LLVector3> &verticesp,
+                                          LLStrider<LLVector3> &normalsp,
+                                          LLStrider<LLVector2> &texCoords0p,
+                                          LLStrider<LLVector2> &texCoords1p,
+                                          LLStrider<U16> &indicesp,
+                                          U32 &index_offset)
 {
 	S32 i, x, y;
 
@@ -982,6 +986,49 @@ LLTerrainPartition::LLTerrainPartition(LLViewerRegion* regionp)
 	mPartitionType = LLViewerRegion::PARTITION_TERRAIN;
 }
 
+// Do not add vertices; honor strict vertex count specified by strider_vertex_count
+void gen_terrain_tangents(U16                    strider_vertex_count,
+                          U32                    strider_index_count,
+                          LLStrider<LLVector3>  &verticesp,
+                          LLStrider<LLVector3>  &normalsp,
+                          LLStrider<LLVector4a> &tangentsp,
+                          LLStrider<LLVector2>  &texCoords0p,
+                          LLStrider<U16>        &indicesp)
+{
+    LL_PROFILE_ZONE_SCOPED
+
+    LLVector4a            *vertices = new LLVector4a[strider_vertex_count];
+    LLVector4a            *normals  = new LLVector4a[strider_vertex_count];
+    LLVector4a            *tangents = new LLVector4a[strider_vertex_count];
+    std::vector<LLVector2> texcoords(strider_vertex_count);
+    std::vector<U16>       indices(strider_index_count);
+
+    for (U16 v = 0; v < strider_vertex_count; ++v)
+    {
+        F32 *vert    = verticesp[v].mV;
+        vertices[v]  = LLVector4a(vert[0], vert[1], vert[2], 1.f);
+        F32 *n       = normalsp[v].mV;
+        normals[v]   = LLVector4a(n[0], n[1], n[2], 1.f);
+        tangents[v]  = tangentsp[v];
+        texcoords[v] = texCoords0p[v];
+    }
+    for (U32 i = 0; i < strider_index_count; ++i)
+    {
+        indices[i] = indicesp[i];
+    }
+
+    LLCalculateTangentArray(strider_vertex_count, vertices, normals, texcoords.data(), strider_index_count / 3, indices.data(), tangents);
+
+    for (U16 v = 0; v < strider_vertex_count; ++v)
+    {
+        tangentsp[v] = tangents[v];
+    }
+
+    delete[] vertices;
+    delete[] normals;
+    delete[] tangents;
+}
+
 void LLTerrainPartition::getGeometry(LLSpatialGroup* group)
 {
     LL_PROFILE_ZONE_SCOPED;
@@ -989,35 +1036,57 @@ void LLTerrainPartition::getGeometry(LLSpatialGroup* group)
 	LLVertexBuffer* buffer = group->mVertexBuffer;
 
 	//get vertex buffer striders
-	LLStrider<LLVector3> vertices;
-	LLStrider<LLVector3> normals;
-	LLStrider<LLVector2> texcoords2;
-	LLStrider<LLVector2> texcoords;
-	LLStrider<U16> indices;
-
-	llassert_always(buffer->getVertexStrider(vertices));
-	llassert_always(buffer->getNormalStrider(normals));
-	llassert_always(buffer->getTexCoord0Strider(texcoords));
-	llassert_always(buffer->getTexCoord1Strider(texcoords2));
-	llassert_always(buffer->getIndexStrider(indices));
-
-	U32 indices_index = 0;
-	U32 index_offset = 0;
-
-	for (std::vector<LLFace*>::iterator i = mFaceList.begin(); i != mFaceList.end(); ++i)
-	{
-		LLFace* facep = *i;
-
-		facep->setIndicesIndex(indices_index);
-		facep->setGeomIndex(index_offset);
-		facep->setVertexBuffer(buffer);
-
-		LLVOSurfacePatch* patchp = (LLVOSurfacePatch*) facep->getViewerObject();
-		patchp->getGeometry(vertices, normals, texcoords, texcoords2, indices);
-
-		indices_index += facep->getIndicesCount();
-		index_offset += facep->getGeomCount();
-	}
+	LLStrider<LLVector3> vertices_start;
+	LLStrider<LLVector3> normals_start;
+	LLStrider<LLVector4a> tangents_start;
+	LLStrider<LLVector2> texcoords_start;
+	LLStrider<LLVector2> texcoords2_start;
+	LLStrider<U16> indices_start;
+
+	llassert_always(buffer->getVertexStrider(vertices_start));
+	llassert_always(buffer->getNormalStrider(normals_start));
+	llassert_always(buffer->getTangentStrider(tangents_start));
+	llassert_always(buffer->getTexCoord0Strider(texcoords_start));
+	llassert_always(buffer->getTexCoord1Strider(texcoords2_start));
+	llassert_always(buffer->getIndexStrider(indices_start));
+
+    U32 indices_index = 0;
+    U32 index_offset = 0;
+
+    {
+        LLStrider<LLVector3> vertices = vertices_start;
+        LLStrider<LLVector3> normals = normals_start;
+        LLStrider<LLVector2> texcoords = texcoords_start;
+        LLStrider<LLVector2> texcoords2 = texcoords2_start;
+        LLStrider<U16> indices = indices_start;
+
+        for (std::vector<LLFace*>::iterator i = mFaceList.begin(); i != mFaceList.end(); ++i)
+        {
+            LLFace* facep = *i;
+
+            facep->setIndicesIndex(indices_index);
+            facep->setGeomIndex(index_offset);
+            facep->setVertexBuffer(buffer);
+
+            LLVOSurfacePatch* patchp = (LLVOSurfacePatch*) facep->getViewerObject();
+            patchp->getTerrainGeometry(vertices, normals, texcoords, texcoords2, indices);
+
+            indices_index += facep->getIndicesCount();
+            index_offset += facep->getGeomCount();
+        }
+    }
+
+    const bool has_tangents = tangents_start.get() != nullptr;
+    if (has_tangents)
+    {
+        LLStrider<LLVector3> vertices = vertices_start;
+        LLStrider<LLVector3> normals = normals_start;
+        LLStrider<LLVector4a> tangents = tangents_start;
+        LLStrider<LLVector2> texcoords = texcoords_start;
+        LLStrider<U16> indices = indices_start;
+
+        gen_terrain_tangents(index_offset, indices_index, vertices, normals, tangents, texcoords, indices);
+    }
 
 	buffer->unmapBuffer();
 	mFaceList.clear();
diff --git a/indra/newview/llvosurfacepatch.h b/indra/newview/llvosurfacepatch.h
index aed67162d1..a3dcb945d1 100644
--- a/indra/newview/llvosurfacepatch.h
+++ b/indra/newview/llvosurfacepatch.h
@@ -63,11 +63,11 @@ public:
 	/*virtual*/ BOOL        updateGeometry(LLDrawable *drawable);
 	/*virtual*/ BOOL		updateLOD();
 	/*virtual*/ void		updateFaceSize(S32 idx);
-	void getGeometry(LLStrider<LLVector3> &verticesp,
-								LLStrider<LLVector3> &normalsp,
-								LLStrider<LLVector2> &texCoords0p,
-								LLStrider<LLVector2> &texCoords1p,
-								LLStrider<U16> &indicesp);
+    void getTerrainGeometry(LLStrider<LLVector3> &verticesp,
+                                LLStrider<LLVector3> &normalsp,
+                                LLStrider<LLVector2> &texCoords0p,
+                                LLStrider<LLVector2> &texCoords1p,
+                                LLStrider<U16> &indicesp);
 
 	/*virtual*/ void updateTextures();
 	/*virtual*/ void setPixelAreaAndAngle(LLAgent &agent); // generate accurate apparent angle and area
diff --git a/indra/newview/llvovolume.cpp b/indra/newview/llvovolume.cpp
index 716a65dbcf..27d2e6af71 100644
--- a/indra/newview/llvovolume.cpp
+++ b/indra/newview/llvovolume.cpp
@@ -996,7 +996,7 @@ LLDrawable *LLVOVolume::createDrawable(LLPipeline *pipeline)
     {
         updateReflectionProbePtr();
     }
-
+    
 	updateRadius();
 	bool force_update = true; // avoid non-alpha mDistance update being optimized away
 	mDrawable->updateDistance(*LLViewerCamera::getInstance(), force_update);
@@ -3408,6 +3408,22 @@ bool LLVOVolume::setReflectionProbeIsDynamic(bool is_dynamic)
     return false;
 }
 
+bool LLVOVolume::setReflectionProbeIsMirror(bool is_mirror)
+{
+    LLReflectionProbeParams *param_block = (LLReflectionProbeParams *) getParameterEntry(LLNetworkData::PARAMS_REFLECTION_PROBE);
+    if (param_block)
+    {
+        if (param_block->getIsMirror() != is_mirror)
+        {
+            param_block->setIsMirror(is_mirror);
+            parameterChanged(LLNetworkData::PARAMS_REFLECTION_PROBE, true);
+            return true;
+        }
+    }
+
+    return false;
+}
+
 F32 LLVOVolume::getReflectionProbeAmbiance() const
 {
     const LLReflectionProbeParams* param_block = (const LLReflectionProbeParams*)getParameterEntry(LLNetworkData::PARAMS_REFLECTION_PROBE);
@@ -3456,6 +3472,18 @@ bool LLVOVolume::getReflectionProbeIsDynamic() const
     return false;
 }
 
+bool LLVOVolume::getReflectionProbeIsMirror() const
+{
+    const LLReflectionProbeParams *param_block =
+        (const LLReflectionProbeParams *) getParameterEntry(LLNetworkData::PARAMS_REFLECTION_PROBE);
+    if (param_block)
+    {
+        return param_block->getIsMirror();
+    }
+
+    return false;
+}
+
 U32 LLVOVolume::getVolumeInterfaceID() const
 {
 	if (mVolumeImpl)
@@ -4375,14 +4403,28 @@ void LLVOVolume::updateReflectionProbePtr()
 {
     if (isReflectionProbe())
     {
-        if (mReflectionProbe.isNull())
+        if (mReflectionProbe.isNull() && !getReflectionProbeIsMirror())
         {
             mReflectionProbe = gPipeline.mReflectionMapManager.registerViewerObject(this);
         }
+        else if (mReflectionProbe.isNull() && getReflectionProbeIsMirror())
+		{
+			// Geenz: This is a special case - what we want here is a hero probe.
+			// What we want to do here is instantiate a hero probe from the hero probe manager.
+            gPipeline.mHeroProbeManager.registerViewerObject(this);
+		}
     }
-    else if (mReflectionProbe.notNull())
+    else if (mReflectionProbe.notNull() || getReflectionProbeIsMirror())
     {
-        mReflectionProbe = nullptr;
+        if (mReflectionProbe.notNull())
+        {
+            mReflectionProbe = nullptr;
+        }
+
+		if (getReflectionProbeIsMirror())
+        {
+            gPipeline.mHeroProbeManager.unregisterViewerObject(this);
+        }
     }
 }
 
diff --git a/indra/newview/llvovolume.h b/indra/newview/llvovolume.h
index aadc1fbcf3..cac09609b3 100644
--- a/indra/newview/llvovolume.h
+++ b/indra/newview/llvovolume.h
@@ -301,12 +301,14 @@ public:
     bool setReflectionProbeNearClip(F32 near_clip);
     bool setReflectionProbeIsBox(bool is_box);
     bool setReflectionProbeIsDynamic(bool is_dynamic);
+    bool setReflectionProbeIsMirror(bool is_mirror);
 
     BOOL isReflectionProbe() const override;
     F32 getReflectionProbeAmbiance() const;
     F32 getReflectionProbeNearClip() const;
     bool getReflectionProbeIsBox() const;
     bool getReflectionProbeIsDynamic() const;
+    bool getReflectionProbeIsMirror() const;
 
 	// Flexible Objects
 	U32 getVolumeInterfaceID() const;
diff --git a/indra/newview/pipeline.cpp b/indra/newview/pipeline.cpp
index f740fa60be..9d90002eb9 100644
--- a/indra/newview/pipeline.cpp
+++ b/indra/newview/pipeline.cpp
@@ -198,8 +198,11 @@ F32 LLPipeline::RenderScreenSpaceReflectionDepthRejectBias;
 F32 LLPipeline::RenderScreenSpaceReflectionAdaptiveStepMultiplier;
 S32 LLPipeline::RenderScreenSpaceReflectionGlossySamples;
 S32 LLPipeline::RenderBufferVisualization;
+bool LLPipeline::RenderMirrors;
 LLTrace::EventStatHandle<S64> LLPipeline::sStatBatchSize("renderbatchsize");
 
+const U32 LLPipeline::MAX_BAKE_WIDTH = 512;
+
 const F32 BACKLIGHT_DAY_MAGNITUDE_OBJECT = 0.1f;
 const F32 BACKLIGHT_NIGHT_MAGNITUDE_OBJECT = 0.08f;
 const F32 ALPHA_BLEND_CUTOFF = 0.598f;
@@ -555,6 +558,7 @@ void LLPipeline::init()
     connectRefreshCachedSettingsSafe("RenderScreenSpaceReflectionAdaptiveStepMultiplier");
     connectRefreshCachedSettingsSafe("RenderScreenSpaceReflectionGlossySamples");
 	connectRefreshCachedSettingsSafe("RenderBufferVisualization");
+    connectRefreshCachedSettingsSafe("RenderMirrors");
 	gSavedSettings.getControl("RenderAutoHideSurfaceAreaLimit")->getCommitSignal()->connect(boost::bind(&LLPipeline::refreshCachedSettings));
 }
 
@@ -638,6 +642,7 @@ void LLPipeline::cleanup()
 	mCubeVB = NULL;
 
     mReflectionMapManager.cleanup();
+    mHeroProbeManager.cleanup();
 }
 
 //============================================================================
@@ -764,13 +769,27 @@ LLPipeline::eFBOStatus LLPipeline::doAllocateScreenBuffer(U32 resX, U32 resY)
 bool LLPipeline::allocateScreenBuffer(U32 resX, U32 resY, U32 samples)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
-    if (mRT == &mMainRT && sReflectionProbesEnabled)
+    if (mRT == &mMainRT)
     { // hacky -- allocate auxillary buffer
+
         gCubeSnapshot = TRUE;
         mReflectionMapManager.initReflectionMaps();
+        mHeroProbeManager.initReflectionMaps();
+
+        if (sReflectionProbesEnabled)
+        {
+            gCubeSnapshot = TRUE;
+            mReflectionMapManager.initReflectionMaps();
+        }
+
         mRT = &mAuxillaryRT;
         U32 res = mReflectionMapManager.mProbeResolution * 4;  //multiply by 4 because probes will be 16x super sampled
         allocateScreenBuffer(res, res, samples);
+
+		res = mHeroProbeManager.mProbeResolution; // We also scale the hero probe RT to the probe res since we don't super sample it.
+        mRT = &mHeroProbeRT;
+        allocateScreenBuffer(res, res, samples);
+
         mRT = &mMainRT;
         gCubeSnapshot = FALSE;
     }
@@ -1043,6 +1062,12 @@ void LLPipeline::refreshCachedSettings()
     RenderScreenSpaceReflectionAdaptiveStepMultiplier = gSavedSettings.getF32("RenderScreenSpaceReflectionAdaptiveStepMultiplier");
     RenderScreenSpaceReflectionGlossySamples = gSavedSettings.getS32("RenderScreenSpaceReflectionGlossySamples");
 	RenderBufferVisualization = gSavedSettings.getS32("RenderBufferVisualization");
+    if (gSavedSettings.getBOOL("RenderMirrors") != (BOOL)RenderMirrors)
+    {
+        RenderMirrors = gSavedSettings.getBOOL("RenderMirrors");
+        LLViewerShaderMgr::instance()->clearShaderCache();
+        LLViewerShaderMgr::instance()->setShaders();
+    }
     sReflectionProbesEnabled = LLFeatureManager::getInstance()->isFeatureAvailable("RenderReflectionsEnabled") && gSavedSettings.getBOOL("RenderReflectionsEnabled");
 	RenderSpotLight = nullptr;
 
@@ -1072,7 +1097,6 @@ void LLPipeline::releaseGLBuffers()
 	releaseLUTBuffers();
 
 	mWaterDis.release();
-    mBake.release();
 	
     mSceneMap.release();
 
@@ -1151,9 +1175,6 @@ void LLPipeline::createGLBuffers()
     stop_glerror();
 	assertInitialized();
 
-    // Use FBO for bake tex
-    mBake.allocate(512, 512, GL_RGBA, true); // SL-12781 Build > Upload > Model; 3D Preview
-
 	stop_glerror();
 
 	GLuint resX = gViewerWindow->getWorldViewWidthRaw();
@@ -2394,6 +2415,26 @@ void LLPipeline::doOcclusion(LLCamera& camera)
 
         gGL.setColorMask(true, true);
     }
+    
+    if (sReflectionProbesEnabled && sUseOcclusion > 1 && !LLPipeline::sShadowRender && !gCubeSnapshot)
+    {
+        gGL.setColorMask(false, false);
+        LLGLDepthTest depth(GL_TRUE, GL_FALSE);
+        LLGLDisable cull(GL_CULL_FACE);
+
+        gOcclusionCubeProgram.bind();
+
+        if (mCubeVB.isNull())
+        { //cube VB will be used for issuing occlusion queries
+            mCubeVB = ll_create_cube_vb(LLVertexBuffer::MAP_VERTEX);
+        }
+        mCubeVB->setBuffer();
+
+        mHeroProbeManager.doOcclusion();
+        gOcclusionCubeProgram.unbind();
+
+        gGL.setColorMask(true, true);
+    }
 
     if (LLPipeline::sUseOcclusion > 1 &&
 		(sCull->hasOcclusionGroups() || LLVOCachePartition::sNeedsOcclusionCheck))
@@ -3771,6 +3812,7 @@ void LLPipeline::renderGeomDeferred(LLCamera& camera, bool do_occlusion)
         {
             //update reflection probe uniform
             mReflectionMapManager.updateUniforms();
+            mHeroProbeManager.updateUniforms();
         }
 
 		U32 cur_type = 0;
@@ -6536,7 +6578,7 @@ void LLPipeline::renderAlphaObjects(bool rigged)
                 LLGLSLShader::sCurBoundShaderPtr->uniform1i(LLShaderMgr::SUN_UP_FACTOR, sun_up);
                 LLGLSLShader::sCurBoundShaderPtr->uniform1f(LLShaderMgr::DEFERRED_SHADOW_TARGET_WIDTH, (float)target_width);
                 LLGLSLShader::sCurBoundShaderPtr->setMinimumAlpha(ALPHA_BLEND_CUTOFF);
-                mSimplePool->pushRiggedGLTFBatch(*pparams, lastAvatar, lastMeshId);
+                LLRenderPass::pushRiggedGLTFBatch(*pparams, lastAvatar, lastMeshId);
             }
             else
             {
@@ -6562,7 +6604,7 @@ void LLPipeline::renderAlphaObjects(bool rigged)
                 LLGLSLShader::sCurBoundShaderPtr->uniform1i(LLShaderMgr::SUN_UP_FACTOR, sun_up);
                 LLGLSLShader::sCurBoundShaderPtr->uniform1f(LLShaderMgr::DEFERRED_SHADOW_TARGET_WIDTH, (float)target_width);
                 LLGLSLShader::sCurBoundShaderPtr->setMinimumAlpha(ALPHA_BLEND_CUTOFF);
-                mSimplePool->pushGLTFBatch(*pparams);
+                LLRenderPass::pushGLTFBatch(*pparams);
             }
             else
             {
@@ -8209,6 +8251,7 @@ void LLPipeline::renderDeferredLighting()
                           LLPipeline::RENDER_TYPE_CONTROL_AV,
                           LLPipeline::RENDER_TYPE_ALPHA_MASK,
                           LLPipeline::RENDER_TYPE_FULLBRIGHT_ALPHA_MASK,
+						  LLPipeline::RENDER_TYPE_TERRAIN,
                           LLPipeline::RENDER_TYPE_WATER,
                           END_RENDER_TYPES);
 
@@ -8612,6 +8655,17 @@ void LLPipeline::bindReflectionProbes(LLGLSLShader& shader)
         mReflectionMapManager.mIrradianceMaps->bind(channel);
         bound = true;
     }
+    
+	if (RenderMirrors)
+    {
+        channel = shader.enableTexture(LLShaderMgr::HERO_PROBE, LLTexUnit::TT_CUBE_MAP_ARRAY);
+        if (channel > -1 && mHeroProbeManager.mTexture.notNull())
+        {
+            mHeroProbeManager.mTexture->bind(channel);
+            bound = true;
+        }
+    }
+     
 
     if (bound)
     {
@@ -10826,3 +10880,12 @@ void LLPipeline::rebuildDrawInfo()
     }
 }
 
+void LLPipeline::rebuildTerrain()
+{
+    for (LLWorld::region_list_t::const_iterator iter = LLWorld::getInstance()->getRegionList().begin();
+        iter != LLWorld::getInstance()->getRegionList().end(); ++iter)
+    {
+        LLViewerRegion* region = *iter;
+        region->dirtyAllPatches();
+    }
+}
diff --git a/indra/newview/pipeline.h b/indra/newview/pipeline.h
index 88a7eab813..e8c6da1473 100644
--- a/indra/newview/pipeline.h
+++ b/indra/newview/pipeline.h
@@ -39,6 +39,7 @@
 #include "lldrawable.h"
 #include "llrendertarget.h"
 #include "llreflectionmapmanager.h"
+#include "llheroprobemanager.h"
 
 #include <stack>
 
@@ -133,6 +134,8 @@ public:
 
     // rebuild all LLVOVolume render batches
     void rebuildDrawInfo();
+    // Rebuild all terrain
+    void rebuildTerrain();
 
     // Clear LLFace mVertexBuffer pointers
 	void resetVertexBuffers(LLDrawable* drawable);
@@ -458,6 +461,7 @@ public:
     void handleShadowDetailChanged();
 
     LLReflectionMapManager mReflectionMapManager;
+    LLHeroProbeManager mHeroProbeManager;
 
 private:
 	void unloadShaders();
@@ -694,8 +698,12 @@ public:
     RenderTargetPack mMainRT;
 
     // auxillary 512x512 render target pack
+    // used by reflection probes and dynamic texture bakes
     RenderTargetPack mAuxillaryRT;
 
+	// Auxillary render target pack scaled to the hero probe's per-face size.
+    RenderTargetPack mHeroProbeRT;
+
     // currently used render target pack
     RenderTargetPack* mRT;
 
@@ -754,7 +762,7 @@ public:
 	//water distortion texture (refraction)
 	LLRenderTarget				mWaterDis;
 
-    LLRenderTarget				mBake;
+    static const U32 MAX_BAKE_WIDTH;
 
 	//texture for making the glow
 	LLRenderTarget				mGlow[3];
@@ -1047,6 +1055,7 @@ public:
 	static F32 RenderScreenSpaceReflectionAdaptiveStepMultiplier;
 	static S32 RenderScreenSpaceReflectionGlossySamples;
 	static S32 RenderBufferVisualization;
+	static bool RenderMirrors;
 };
 
 void render_bbox(const LLVector3 &min, const LLVector3 &max);
diff --git a/indra/newview/skins/default/xui/en/floater_tools.xml b/indra/newview/skins/default/xui/en/floater_tools.xml
index 9966fe0b56..72c78fec3d 100644
--- a/indra/newview/skins/default/xui/en/floater_tools.xml
+++ b/indra/newview/skins/default/xui/en/floater_tools.xml
@@ -2410,7 +2410,6 @@ even though the user gets a free copy.
              name="object_horizontal"
              top_pad="10"
              width="278" />
-
             <check_box
              height="16"
              label="Light"
@@ -2560,16 +2559,52 @@ even though the user gets a free copy.
              name="Box"
              value="Box"/>
           </combo_box>
+
           <check_box
-             height="16"
-             label="Dynamic"
+           height="16"
+           label="Dynamic"
+           layout="topleft"
+           left="10"
+           name="Probe Dynamic"
+           tool_tip="When enabled, Avatars will appear in reflections within this probe's influence volume."
+           bottom_delta="19"
+           width="60" />
+          
+          <text
+            bottom_delta="-8"
+             type="string"
+             length="1"
+             follows="left|top"
+             height="10"
              layout="topleft"
              left="10"
-             name="Probe Dynamic"
-             tool_tip="When enabled, Avatars will appear in reflections within this probe's influence volume."
-             bottom_delta="19"
-             width="60" />
-          <spinner bottom_delta="19"
+             name="Probe Update Label"
+             text_readonly_color="LabelDisabledColor"
+             width="100">
+            Probe Update
+          </text>
+          <combo_box
+			   height="19"
+			   top_delta="0"
+         left="144"
+			   follows="left|top"
+			   name="Probe Update Type"
+			   tool_tip="Determines how the probe updates.  Static updates the slowest and without avatars.  Dynamic updates more frequently, with avatars visible in the probes.  Mirror turns this probe into a realtime planar projected mirror probe, but does not calculate ambiance."
+			   width="108">
+            <combo_box.item
+             label="Static"
+             name="Static"
+             value="Static" />
+            <combo_box.item
+             label="Dynamic"
+             name="Dynamic"
+             value="Dynamic"/>
+            <combo_box.item
+             label="Mirror"
+             name="Mirror"
+             value="Mirror"/>
+          </combo_box>
+          <spinner bottom_delta="17"
                    decimal_digits="3"
                    follows="left|top"
                    height="16"
diff --git a/indra/newview/skins/default/xui/en/menu_viewer.xml b/indra/newview/skins/default/xui/en/menu_viewer.xml
index 660f4b62c7..9b238693e0 100644
--- a/indra/newview/skins/default/xui/en/menu_viewer.xml
+++ b/indra/newview/skins/default/xui/en/menu_viewer.xml
@@ -3297,6 +3297,13 @@ function="World.EnvPreset"
             <menu_item_call.on_click
              function="Advanced.ClearShaderCache" />
           </menu_item_call>
+          <menu_item_call
+            enabled="true"
+            label="Rebuild Terrain"
+            name="Rebuild Terrain">
+            <menu_item_call.on_click
+             function="Advanced.RebuildTerrain" />
+          </menu_item_call>
           <menu_item_separator />
           <menu_item_call
             enabled="true"
diff --git a/indra/newview/skins/default/xui/en/notifications.xml b/indra/newview/skins/default/xui/en/notifications.xml
index d642ea162c..df9f53686e 100644
--- a/indra/newview/skins/default/xui/en/notifications.xml
+++ b/indra/newview/skins/default/xui/en/notifications.xml
@@ -4004,7 +4004,7 @@ Are you sure you want to return objects owned by [USER_NAME]?
 Couldn&apos;t set region textures:
 Terrain texture [TEXTURE_NUM] has an invalid bit depth of [TEXTURE_BIT_DEPTH].
 
-Replace texture [TEXTURE_NUM] with a 24-bit [MAX_SIZE]x[MAX_SIZE] or smaller image then click &quot;Apply&quot; again.
+Replace texture [TEXTURE_NUM] with an RGB [MAX_SIZE]x[MAX_SIZE] or smaller image then click &quot;Apply&quot; again.
   <tag>fail</tag>
   </notification>
 
@@ -4015,7 +4015,7 @@ Replace texture [TEXTURE_NUM] with a 24-bit [MAX_SIZE]x[MAX_SIZE] or smaller ima
 Couldn&apos;t set region textures:
 Terrain texture [TEXTURE_NUM] is too large at [TEXTURE_SIZE_X]x[TEXTURE_SIZE_Y].
 
-Replace texture [TEXTURE_NUM] with a 24-bit [MAX_SIZE]x[MAX_SIZE] or smaller image then click &quot;Apply&quot; again.
+Replace texture [TEXTURE_NUM] with an RGB [MAX_SIZE]x[MAX_SIZE] or smaller image then click &quot;Apply&quot; again.
   </notification>
 
   <notification
diff --git a/indra/newview/skins/default/xui/en/panel_region_terrain.xml b/indra/newview/skins/default/xui/en/panel_region_terrain.xml
index 2aaea04a6d..88855ab739 100644
--- a/indra/newview/skins/default/xui/en/panel_region_terrain.xml
+++ b/indra/newview/skins/default/xui/en/panel_region_terrain.xml
@@ -76,29 +76,61 @@
      left="8"
      top="30"
      width="460" />
+    <combo_box
+     layout="topleft"
+     left="10"
+     top="105"
+     follows="left|top"
+     name="terrain_material_type"
+     width="170">
+        <combo_box.item
+         label="Terrain Textures"
+         name="Textures"
+         value="Textures" />
+        <combo_box.item
+         label="Terrain PBR Materials"
+         name="PBRMaterials"
+         value="PBRMaterials" />
+    </combo_box>
     <text
      type="string"
      length="1"
      follows="left|top"
+     halign="left"
+     valign="center"
      height="20"
      layout="topleft"
-     left="10"
      name="detail_texture_text"
-     top="110"
-     width="300">
-        Terrain Textures (requires 1024x1024, 24 bit .tga files)
+     top_delta="0"
+     left_delta="0"
+     width="170">
+        Terrain Textures
+    </text>
+    <text
+     type="string"
+     length="1"
+     halign="left"
+     valign="center"
+     follows="left|top"
+     height="20"
+     layout="topleft"
+     top_delta="0"
+     left_delta="180"
+     name="detail_texture_limits_text"
+     width="200">
+        Maximum size: 1024x1024
     </text>
     <texture_picker
      follows="left|top"
      height="100"
      layout="topleft"
-     left_delta="0"
+     left="10"
      name="texture_detail_0"
      default_image_id="0bc58228-74a0-7e83-89bc-5c23464bcec5"
-     top_delta="20"
+     top_delta="30"
      width="100" />
     <texture_picker
-     follows="left|top"
+     follows="top"
      height="100"
      layout="topleft"
      left_pad="10"
@@ -124,6 +156,50 @@
      default_image_id="53a2f406-4895-1d13-d541-d2e3b86bc19c"
      top_delta="0"
      width="100" />
+    <texture_picker
+     visible="false"
+     follows="left|top"
+     height="100"
+     layout="topleft"
+     left="10"
+     name="material_detail_0"
+     pick_type="material"
+     allow_no_texture="true"
+     top_delta="0"
+     width="100" />
+    <texture_picker
+     visible="false"
+     follows="left|top"
+     height="100"
+     layout="topleft"
+     left_pad="10"
+     name="material_detail_1"
+     pick_type="material"
+     allow_no_texture="true"
+     top_delta="0"
+     width="100" />
+    <texture_picker
+     visible="false"
+     follows="left|top"
+     height="100"
+     layout="topleft"
+     left_pad="10"
+     name="material_detail_2"
+     pick_type="material"
+     allow_no_texture="true"
+     top_delta="0"
+     width="100" />
+    <texture_picker
+     visible="false"
+     follows="left|top"
+     height="100"
+     layout="topleft"
+     left_pad="10"
+     name="material_detail_3"
+     pick_type="material"
+     allow_no_texture="true"
+     top_delta="0"
+     width="100" />
     <text
      type="string"
      length="1"