Merge branch 'main' of https://github.com/secondlife/viewer into DRTVWR-600-maint-A

# Conflicts:
#	indra/llappearance/llavatarappearance.h
#	indra/llimage/llimage.cpp
#	indra/llmath/llvolume.cpp
#	indra/llmath/llvolume.h
#	indra/llprimitive/llgltfmaterial.h
#	indra/llrender/llrendertarget.cpp
#	indra/llrender/llshadermgr.cpp
#	indra/newview/lldynamictexture.cpp
#	indra/newview/llenvironment.cpp
#	indra/newview/llfetchedgltfmaterial.cpp
#	indra/newview/llfloaterimagepreview.cpp
#	indra/newview/llfloaterimagepreview.h
#	indra/newview/llfloaterregioninfo.cpp
#	indra/newview/llfloaterregioninfo.h
#	indra/newview/llmaniprotate.cpp
#	indra/newview/llmaniptranslate.cpp
#	indra/newview/llpanelvolume.cpp
#	indra/newview/llselectmgr.cpp
#	indra/newview/llselectmgr.h
#	indra/newview/llsurface.cpp
#	indra/newview/llsurface.h
#	indra/newview/llsurfacepatch.cpp
#	indra/newview/lltexturectrl.cpp
#	indra/newview/lltexturectrl.h
#	indra/newview/lltinygltfhelper.cpp
#	indra/newview/llviewertexture.cpp
#	indra/newview/llviewerwindow.cpp
#	indra/newview/llviewerwindow.h
#	indra/newview/llvlcomposition.cpp
#	indra/newview/llvlcomposition.h
#	indra/newview/llvocache.cpp
#	indra/newview/llvovolume.cpp
#	indra/newview/pipeline.cpp

34 files changed, 1282 insertions, 206 deletions

diff --git a/indra/newview/app_settings/shaders/class1/deferred/avatarEyesV.glsl b/indra/newview/app_settings/shaders/class1/deferred/avatarEyesV.glsl
index d9a6c9e5f1..d3ca3ec8c1 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/avatarEyesV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/avatarEyesV.glsl
@@ -26,6 +26,7 @@
 uniform mat3 normal_matrix;
 uniform mat4 texture_matrix0;
 uniform mat4 modelview_projection_matrix;
+uniform mat4 modelview_matrix;
 
 in vec3 position;
 in vec3 normal;
@@ -35,10 +36,12 @@ in vec2 texcoord0;
 out vec3 vary_normal;
 out vec4 vertex_color;
 out vec2 vary_texcoord0;
+out vec3 vary_position;
 
 void main()
 {
     //transform vertex
+    vary_position = (modelview_matrix * vec4(position.xyz, 1.0)).xyz;
     gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0);
     vary_texcoord0 = (texture_matrix0 * vec4(texcoord0,0,1)).xy;
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/avatarF.glsl b/indra/newview/app_settings/shaders/class1/deferred/avatarF.glsl
index 63d8e12e62..b904df3a1b 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/avatarF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/avatarF.glsl
@@ -25,7 +25,7 @@
 
 /*[EXTRA_CODE_HERE]*/
 
-out vec4 frag_data[3];
+out vec4 frag_data[4];
 
 uniform sampler2D diffuseMap;
 
@@ -33,11 +33,14 @@ 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)
@@ -48,6 +51,7 @@ void main()
     frag_data[0] = vec4(diff.rgb, 0.0);
     frag_data[1] = vec4(0,0,0,0);
     vec3 nvn = normalize(vary_normal);
-    frag_data[2] = vec4(encode_normal(nvn.xyz), 0.0, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[2] = vec4(nvn.xyz, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[3] = vec4(0);
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/avatarV.glsl b/indra/newview/app_settings/shaders/class1/deferred/avatarV.glsl
index 74d16592de..aabbbac12a 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/blurLightF.glsl b/indra/newview/app_settings/shaders/class1/deferred/blurLightF.glsl
index 19fc660c2d..8627ab1852 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/blurLightF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/blurLightF.glsl
@@ -1,24 +1,24 @@
-/**
+/** 
  * @file blurLightF.glsl
  *
  * $LicenseInfo:firstyear=2007&license=viewerlgpl$
  * Second Life Viewer Source Code
  * Copyright (C) 2007, 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
  * $/LicenseInfo$
  */
@@ -40,18 +40,18 @@ uniform float kern_scale;
 in vec2 vary_fragcoord;
 
 vec4 getPosition(vec2 pos_screen);
-vec3 getNorm(vec2 pos_screen);
+vec4 getNorm(vec2 pos_screen);
 
-void main()
+void main() 
 {
     vec2 tc = vary_fragcoord.xy;
-    vec3 norm = getNorm(tc);
+    vec4 norm = getNorm(tc);
     vec3 pos = getPosition(tc).xyz;
     vec4 ccol = texture(lightMap, tc).rgba;
-
+  
     vec2 dlt = kern_scale * delta / (1.0+norm.xy*norm.xy);
     dlt /= max(-pos.z*dist_factor, 1.0);
-
+    
     vec2 defined_weight = kern[0].xy; // special case the first (centre) sample's weight in the blur; we have to sample it anyway so we get it for 'free'
     vec4 col = defined_weight.xyxx * ccol;
 
@@ -75,15 +75,15 @@ void main()
     k[1] = (k[0]+k[2])*0.5f;
     k[3] = (k[2]+k[4])*0.5f;
     k[5] = (k[4]+k[6])*0.5f;
-
+    
     for (int i = 1; i < 7; i++)
     {
         vec2 samptc = tc + k[i].z*dlt*2.0;
         samptc /= screen_res;
-        vec3 samppos = getPosition(samptc).xyz;
+        vec3 samppos = getPosition(samptc).xyz; 
 
         float d = dot(norm.xyz, samppos.xyz-pos.xyz);// dist from plane
-
+        
         if (d*d <= pointplanedist_tolerance_pow2)
         {
             col += texture(lightMap, samptc)*k[i].xyxx;
@@ -95,10 +95,10 @@ void main()
     {
         vec2 samptc = tc - k[i].z*dlt*2.0;
         samptc /= screen_res;
-        vec3 samppos = getPosition(samptc).xyz;
+        vec3 samppos = getPosition(samptc).xyz; 
 
         float d = dot(norm.xyz, samppos.xyz-pos.xyz);// dist from plane
-
+        
         if (d*d <= pointplanedist_tolerance_pow2)
         {
             col += texture(lightMap, samptc)*k[i].xyxx;
@@ -108,7 +108,7 @@ void main()
 
     col /= defined_weight.xyxx;
     //col.y *= col.y;
-
+    
     frag_color = max(col, vec4(0));
 
 #ifdef IS_AMD_CARD
diff --git a/indra/newview/app_settings/shaders/class1/deferred/bumpF.glsl b/indra/newview/app_settings/shaders/class1/deferred/bumpF.glsl
index 11deecafbb..2cc3085cd0 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/bumpF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/bumpF.glsl
@@ -37,11 +37,13 @@ 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)
@@ -60,6 +62,6 @@ void main()
         frag_data[1] = vertex_color.aaaa; // spec
         //frag_data[1] = vec4(vec3(vertex_color.a), vertex_color.a+(1.0-vertex_color.a)*vertex_color.a); // spec - from former class3 - maybe better, but not so well tested
         vec3 nvn = normalize(tnorm);
-        frag_data[2] = vec4(encode_normal(nvn), vertex_color.a, GBUFFER_FLAG_HAS_ATMOS);
-        frag_data[3] = vec4(0);
+        frag_data[2] = vec4(nvn, GBUFFER_FLAG_HAS_ATMOS);
+        frag_data[3] = vec4(vertex_color.a, 0, 0, 0);
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/bumpV.glsl b/indra/newview/app_settings/shaders/class1/deferred/bumpV.glsl
index 4ac757be65..a381392f6c 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/deferredUtil.glsl b/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
index 5ef3d63eb2..01543732d0 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
@@ -50,6 +50,7 @@ SOFTWARE.
 
 uniform sampler2D   normalMap;
 uniform sampler2D   depthMap;
+uniform sampler2D emissiveRect;
 uniform sampler2D projectionMap; // rgba
 uniform sampler2D brdfLut;
 
@@ -140,40 +141,11 @@ vec2 getScreenCoordinate(vec2 screenpos)
     return sc - vec2(1.0, 1.0);
 }
 
-// See: https://aras-p.info/texts/CompactNormalStorage.html
-//      Method #4: Spheremap Transform, Lambert Azimuthal Equal-Area projection
-vec3 getNorm(vec2 screenpos)
+vec4 getNorm(vec2 screenpos)
 {
-   vec2 enc = texture(normalMap, screenpos.xy).xy;
-   vec2 fenc = enc*4-2;
-   float f = dot(fenc,fenc);
-   float g = sqrt(1-f/4);
-   vec3 n;
-   n.xy = fenc*g;
-   n.z = 1-f/2;
-   return n;
-}
-
-vec3 getNormalFromPacked(vec4 packedNormalEnvIntensityFlags)
-{
-   vec2 enc = packedNormalEnvIntensityFlags.xy;
-   vec2 fenc = enc*4-2;
-   float f = dot(fenc,fenc);
-   float g = sqrt(1-f/4);
-   vec3 n;
-   n.xy = fenc*g;
-   n.z = 1-f/2;
-   return normalize(n); // TODO: Is this normalize redundant?
-}
-
-// return packedNormalEnvIntensityFlags since GBUFFER_FLAG_HAS_PBR needs .w
-// See: C++: addDeferredAttachments(), GLSL: softenLightF
-vec4 getNormalEnvIntensityFlags(vec2 screenpos, out vec3 n, out float envIntensity)
-{
-    vec4 packedNormalEnvIntensityFlags = texture(normalMap, screenpos.xy);
-    n = getNormalFromPacked( packedNormalEnvIntensityFlags );
-    envIntensity = packedNormalEnvIntensityFlags.z;
-    return packedNormalEnvIntensityFlags;
+    vec4 norm = texture(normalMap, screenpos.xy);
+    norm.xyz = normalize(norm.xyz);
+    return norm;
 }
 
 // get linear depth value given a depth buffer sample d and znear and zfar values
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskF.glsl
index c2fb3201f4..1751e17814 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskF.glsl
@@ -31,14 +31,18 @@ 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)
@@ -49,7 +53,7 @@ void main()
     frag_data[0] = vec4(col.rgb, 0.0);
     frag_data[1] = vec4(0,0,0,0); // spec
     vec3 nvn = normalize(vary_normal);
-    frag_data[2] = vec4(encode_normal(nvn.xyz), 0.0, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[2] = vec4(nvn.xyz, GBUFFER_FLAG_HAS_ATMOS);
     frag_data[3] = vec4(0);
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskIndexedF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskIndexedF.glsl
index dce1f91bc3..f5b517a8ea 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskIndexedF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskIndexedF.glsl
@@ -28,16 +28,19 @@
 out vec4 frag_data[4];
 
 in vec3 vary_normal;
+in vec3 vary_position;
 
 uniform float minimum_alpha;
 
 in vec4 vertex_color;
 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)
@@ -48,6 +51,6 @@ void main()
     frag_data[0] = vec4(col.rgb, 0.0);
     frag_data[1] = vec4(0,0,0,0);
     vec3 nvn = normalize(vary_normal);
-    frag_data[2] = vec4(encode_normal(nvn.xyz), 0.0, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[2] = vec4(nvn.xyz, GBUFFER_FLAG_HAS_ATMOS);
     frag_data[3] = vec4(0);
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskNoColorF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskNoColorF.glsl
index 1fc719dde5..89ea0c1710 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskNoColorF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseAlphaMaskNoColorF.glsl
@@ -34,8 +34,6 @@ uniform sampler2D diffuseMap;
 in vec3 vary_normal;
 in vec2 vary_texcoord0;
 
-vec2 encode_normal(vec3 n);
-
 void main()
 {
     vec4 col = texture(diffuseMap, vary_texcoord0.xy);
@@ -48,7 +46,7 @@ void main()
     frag_data[0] = vec4(col.rgb, 0.0);
     frag_data[1] = vec4(0,0,0,0); // spec
     vec3 nvn = normalize(vary_normal);
-    frag_data[2] = vec4(encode_normal(nvn.xyz), 0.0, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[2] = vec4(nvn.xyz, GBUFFER_FLAG_HAS_ATMOS);
     frag_data[3] = vec4(0);
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseF.glsl
index d3d375b20a..7f056a51e8 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseF.glsl
@@ -32,17 +32,19 @@ 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
     //frag_data[1] = vec4(vec3(vertex_color.a), vertex_color.a+(1.0-vertex_color.a)*vertex_color.a); // spec - from former class3 - maybe better, but not so well tested
     vec3 nvn = normalize(vary_normal);
-    frag_data[2] = vec4(encode_normal(nvn.xyz), vertex_color.a, GBUFFER_FLAG_HAS_ATMOS);
-    frag_data[3] = vec4(0);
+    frag_data[2] = vec4(nvn.xyz, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[3] = vec4(vertex_color.a, 0, 0, 0);
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseIndexedF.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseIndexedF.glsl
index afdd043c7c..5c73878ba9 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/diffuseIndexedF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/diffuseIndexedF.glsl
@@ -30,12 +30,14 @@ out vec4 frag_data[4];
 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);
 vec3 linear_to_srgb(vec3 c);
 
 void main()
 {
+    mirrorClip(vary_position);
     vec3 col = vertex_color.rgb * diffuseLookup(vary_texcoord0.xy).rgb;
 
     vec3 spec;
@@ -44,6 +46,6 @@ void main()
     frag_data[0] = vec4(col, 0.0);
     frag_data[1] = vec4(spec, vertex_color.a); // spec
     vec3 nvn = normalize(vary_normal);
-    frag_data[2] = vec4(encode_normal(nvn.xyz), vertex_color.a, GBUFFER_FLAG_HAS_ATMOS);
-    frag_data[3] = vec4(0);
+    frag_data[2] = vec4(nvn.xyz, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[3] = vec4(vertex_color.a, 0, 0, 0);
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/diffuseV.glsl b/indra/newview/app_settings/shaders/class1/deferred/diffuseV.glsl
index 304c01ecc3..4bd31cef9e 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/exposureF.glsl b/indra/newview/app_settings/shaders/class1/deferred/exposureF.glsl
index 709b47dcbd..eff7221ae7 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/exposureF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/exposureF.glsl
@@ -1,34 +1,36 @@
-/**
+/** 
  * @file exposureF.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]*/
 
 out vec4 frag_color;
 
 uniform sampler2D emissiveRect;
+#ifdef USE_LAST_EXPOSURE
 uniform sampler2D exposureMap;
+#endif
 
 uniform float dt;
 uniform vec2 noiseVec;
@@ -41,7 +43,7 @@ float lum(vec3 col)
     return dot(l, col);
 }
 
-void main()
+void main() 
 {
     vec2 tc = vec2(0.5,0.5);
 
@@ -51,11 +53,13 @@ void main()
     L /= max_L;
     L = pow(L, 2.0);
     float s = mix(dynamic_exposure_params.z, dynamic_exposure_params.y, L);
-
+    
+#ifdef USE_LAST_EXPOSURE
     float prev = texture(exposureMap, vec2(0.5,0.5)).r;
 
     s = mix(prev, s, min(dt*2.0*abs(prev-s), 0.04));
-
+#endif
+    
     frag_color = max(vec4(s, s, s, dt), vec4(0.0));
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/fullbrightF.glsl b/indra/newview/app_settings/shaders/class1/deferred/fullbrightF.glsl
index ec6a4a502f..52dfed06ae 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/fullbrightF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/fullbrightF.glsl
@@ -1,28 +1,28 @@
-/**
+/** 
  * @file deferred/fullbrightF.glsl
  *
  * $LicenseInfo:firstyear=2007&license=viewerlgpl$
  * Second Life Viewer Source Code
  * Copyright (C) 2007, 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]*/
 
 out vec4 frag_color;
@@ -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 main()
-{
+void mirrorClip(vec3 pos);
 
+void main() 
+{
+    mirrorClip(vary_position);
 #ifdef IS_ALPHA
     waterClip(vary_position.xyz);
 #endif
@@ -88,7 +90,7 @@ void main()
     calcAtmosphericVars(pos.xyz, vec3(0), 1.0, sunlit, amblit, additive, atten);
 
     color.rgb = applySkyAndWaterFog(pos, additive, atten, color).rgb;
-
+    
 #endif
 
 #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/impostorF.glsl b/indra/newview/app_settings/shaders/class1/deferred/impostorF.glsl
index 5561a3d488..99cb23839a 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/impostorF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/impostorF.glsl
@@ -37,7 +37,6 @@ uniform sampler2D specularMap;
 in vec2 vary_texcoord0;
 
 vec3 linear_to_srgb(vec3 c);
-vec2 encode_normal (vec3 n);
 
 void main()
 {
@@ -53,6 +52,6 @@ void main()
 
     frag_data[0] = vec4(col.rgb, 0.0);
     frag_data[1] = spec;
-    frag_data[2] = vec4(encode_normal(norm.xyz),0,GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[2] = vec4(norm.xyz, GBUFFER_FLAG_HAS_ATMOS);
     frag_data[3] = vec4(0);
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl b/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
index b9337a357f..95b2f80e06 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
@@ -1,32 +1,32 @@
-/**
+/** 
  * @file luminanceF.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]*/
 
-// take a luminance sample of diffuseRect and emissiveRect
+// take a luminance sample of diffuseRect and emissiveRect 
 
 out vec4 frag_color;
 
@@ -34,6 +34,8 @@ in vec2 vary_fragcoord;
 
 uniform sampler2D diffuseRect;
 uniform sampler2D emissiveRect;
+uniform sampler2D normalMap;
+uniform float diffuse_luminance_scale;
 
 float lum(vec3 col)
 {
@@ -41,11 +43,25 @@ float lum(vec3 col)
     return dot(l, col);
 }
 
-void main()
+void main() 
 {
     vec2 tc = vary_fragcoord*0.6+0.2;
     tc.y -= 0.1; // HACK - nudge exposure sample down a little bit to favor ground over sky
-    vec3 c = texture(diffuseRect, tc).rgb + texture(emissiveRect, tc).rgb;
+    vec3 c = texture(diffuseRect, tc).rgb;
+    
+    vec4  norm         = texture(normalMap, tc);
+
+    if (!GET_GBUFFER_FLAG(GBUFFER_FLAG_HAS_HDRI) &&
+        !GET_GBUFFER_FLAG(GBUFFER_FLAG_SKIP_ATMOS))
+    {
+        // Apply the diffuse luminance scale to objects but not the sky
+        // Prevents underexposing when looking at bright environments
+        // while still allowing for realistically bright skies.
+        c *= diffuse_luminance_scale;
+    }
+
+    c += texture(emissiveRect, tc).rgb;
+
     float L = lum(c);
     frag_color = vec4(max(L, 0.0));
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/materialV.glsl b/indra/newview/app_settings/shaders/class1/deferred/materialV.glsl
index 5e48ff709f..b6528dfcf8 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/moonF.glsl b/indra/newview/app_settings/shaders/class1/deferred/moonF.glsl
index 03a8518c36..6ef556d7e8 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/moonF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/moonF.glsl
@@ -1,28 +1,28 @@
-/**
+/** 
  * @file class1\deferred\moonF.glsl
  *
  * $LicenseInfo:firstyear=2005&license=viewerlgpl$
  * Second Life Viewer Source Code
  * Copyright (C) 2005, 2020 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]*/
 
 out vec4 frag_data[4];
@@ -34,7 +34,7 @@ uniform sampler2D diffuseMap;
 
 in vec2 vary_texcoord0;
 
-void main()
+void main() 
 {
     // Restore Pre-EEP alpha fade moon near horizon
     float fade = 1.0;
@@ -55,7 +55,7 @@ void main()
 
     frag_data[0] = vec4(0);
     frag_data[1] = vec4(0.0);
-    frag_data[2] = vec4(0.0, 0.0, 0.0, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[2] = vec4(0.0, 0.0, 0.0, GBUFFER_FLAG_SKIP_ATMOS);
     frag_data[3] = vec4(c.rgb, c.a);
 
     // Added and commented out for a ground truth.  Do not uncomment - Geenz
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbrShadowAlphaMaskF.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbrShadowAlphaMaskF.glsl
index c1fb9f5d84..35b7602569 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbrShadowAlphaMaskF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrShadowAlphaMaskF.glsl
@@ -1,24 +1,24 @@
-/**
+/** 
  * @file pbrShadowAlphaMaskF.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
  * $/LicenseInfo$
  */
@@ -33,9 +33,9 @@ in vec4 vertex_color;
 in vec2 vary_texcoord0;
 uniform float minimum_alpha;
 
-void main()
+void main() 
 {
-    float alpha = texture(diffuseMap,vary_texcoord0.xy).a;
+    float alpha = texture(diffuseMap,vary_texcoord0.xy).a * vertex_color.a;
 
     if (alpha < minimum_alpha)
     {
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl
index ed19fba228..380d493636 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl
@@ -1,24 +1,24 @@
-/**
+/** 
  * @file pbropaqueF.glsl
  *
  * $LicenseInfo:firstyear=2022&license=viewerlgpl$
  * 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
  * $/LicenseInfo$
  */
@@ -28,7 +28,7 @@
 
 #ifndef IS_HUD
 
-// deferred opaque implementation
+// deferred opaque implementation 
 
 uniform sampler2D diffuseMap;  //always in sRGB space
 
@@ -54,28 +54,38 @@ in vec2 emissive_texcoord;
 
 uniform float minimum_alpha; // PBR alphaMode: MASK, See: mAlphaCutoff, setAlphaCutoff()
 
-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;
+    basecolor.rgb = srgb_to_linear(basecolor.rgb);
+
+    basecolor *= vertex_color;
+
     if (basecolor.a < minimum_alpha)
     {
         discard;
     }
 
-    vec3 col = vertex_color.rgb * srgb_to_linear(basecolor.rgb);
+    vec3 col = basecolor.rgb;
 
     // from mikktspace.com
     vec3 vNt = texture(bumpMap, normal_texcoord.xy).xyz*2.0-1.0;
     float sign = vary_sign;
     vec3 vN = vary_normal;
     vec3 vT = vary_tangent.xyz;
-
+    
     vec3 vB = sign * cross(vN, vT);
     vec3 tnorm = normalize( vNt.x * vT + vNt.y * vB + vNt.z * vN );
 
@@ -85,7 +95,7 @@ void main()
     //   roughness 0.0
     //   metal     0.0
     vec3 spec = texture(specularMap, metallic_roughness_texcoord.xy).rgb;
-
+    
     spec.g *= roughnessFactor;
     spec.b *= metallicFactor;
 
@@ -102,8 +112,8 @@ void main()
     //emissive = tnorm*0.5+0.5;
     // See: C++: addDeferredAttachments(), GLSL: softenLightF
     frag_data[0] = max(vec4(col, 0.0), vec4(0));                                                   // Diffuse
-    frag_data[1] = max(vec4(spec.rgb,vertex_color.a), vec4(0));                                    // PBR linear packed Occlusion, Roughness, Metal.
-    frag_data[2] = max(vec4(encode_normal(tnorm), vertex_color.a, GBUFFER_FLAG_HAS_PBR), vec4(0)); // normal, environment intensity, flags
+    frag_data[1] = max(vec4(spec.rgb,0.0), vec4(0));                                    // PBR linear packed Occlusion, Roughness, Metal.
+    frag_data[2] = vec4(tnorm, GBUFFER_FLAG_HAS_PBR); // 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/pbropaqueV.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl
index 53e4b732df..fd020afd57 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..0de2d348c3
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainF.glsl
@@ -0,0 +1,347 @@
+/** 
+ * @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_position;
+in vec3 vary_normal;
+in vec3 vary_tangent;
+flat in float vary_sign;
+in vec4 vary_texcoord0;
+in vec4 vary_texcoord1;
+
+void mirrorClip(vec3 position);
+
+float terrain_mix(TerrainMix tm, vec4 tms4);
+
+void main()
+{
+    // Make sure we clip the terrain if we're in a mirror.
+    mirrorClip(vary_position);
+
+#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 pbr_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
+        );
+        pbr_mix = mix_pbr(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
+        );
+        pbr_mix = mix_pbr(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
+        );
+        pbr_mix = mix_pbr(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
+        );
+        pbr_mix = mix_pbr(pbr_mix, mix2, tm.weight.w);
+        break;
+    default:
+        break;
+    }
+
+    float minimum_alpha = terrain_mix(tm, minimum_alphas);
+    if (pbr_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 = pbr_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 mix_emissive pbr_mix.emissive
+#else
+#define mix_emissive vec3(0)
+#endif
+#if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
+#define mix_orm pbr_mix.orm
+#elif (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS)
+#define mix_orm vec3(1.0, pbr_mix.rm)
+#else
+// Matte plastic potato terrain
+#define mix_orm vec3(1.0, 1.0, 0.0)
+#endif
+    frag_data[0] = max(vec4(pbr_mix.col.xyz, 0.0), vec4(0));                                                   // Diffuse
+    frag_data[1] = max(vec4(mix_orm.rgb, base_color_factor_alpha), vec4(0));                                    // PBR linear packed Occlusion, Roughness, Metal.
+    frag_data[2] = vec4(tnorm, GBUFFER_FLAG_HAS_PBR); // normal, flags
+    frag_data[3] = max(vec4(mix_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..ed52297314
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
@@ -0,0 +1,96 @@
+/**
+ * @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_matrix;
+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;
+out vec3 vary_position;
+
+// *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 terrain_texture_transform(vec2 vertex_texcoord, vec4[2] khr_gltf_transform);
+vec3 terrain_tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform);
+
+void main()
+{
+    //transform vertex
+    gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0);
+    vary_position = (modelview_matrix*vec4(position.xyz, 1.0)).xyz;
+
+    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(terrain_tangent_space_transform(vec4(t, tangent.w), n, texture_base_color_transform));
+    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 = terrain_texture_transform(position.xy, texture_base_color_transform);
+    // yz
+    vary_coords[0].zw = terrain_texture_transform(position.yz, texture_base_color_transform);
+    // (-x)z
+    vary_coords[1].xy = terrain_texture_transform(position.xz * vec2(-1, 1), texture_base_color_transform);
+#elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
+    vary_texcoord0.xy = terrain_texture_transform(position.xy, texture_base_color_transform);
+#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/postDeferredGammaCorrect.glsl b/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
index 7a25f63260..a0eb6cfbb8 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
@@ -97,6 +97,7 @@ vec3 toneMapACES_Hill(vec3 color)
 
 uniform float exposure;
 uniform float gamma;
+uniform float aces_mix;
 
 vec3 toneMap(vec3 color)
 {
@@ -106,7 +107,7 @@ vec3 toneMap(vec3 color)
     color *= exposure * exp_scale;
 
     // mix ACES and Linear here as a compromise to avoid over-darkening legacy content
-    color = mix(toneMapACES_Hill(color), color, 0.3);
+    color = mix(toneMapACES_Hill(color), color, aces_mix);
 #endif
 
     return color;
@@ -152,6 +153,15 @@ float noise(vec2 x) {
 
 //=============================
 
+void debugExposure(inout vec3 color)
+{
+    float exp_scale = texture(exposureMap, vec2(0.5,0.5)).r;
+    exp_scale *= 0.5;
+    if (abs(vary_fragcoord.y-exp_scale) < 0.01 && vary_fragcoord.x < 0.1)
+    {
+        color = vec3(1,0,0);
+    }
+}
 
 vec3 legacyGamma(vec3 color)
 {
@@ -181,6 +191,7 @@ void main()
     vec3 nz = vec3(noise(seed.rg), noise(seed.gb), noise(seed.rb));
     diff.rgb += nz*0.003;
 
+    //debugExposure(diff.rgb);
     frag_color = max(diff, vec4(0));
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/skyF.glsl b/indra/newview/app_settings/shaders/class1/deferred/skyF.glsl
index a07a4301bc..785c748234 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/skyF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/skyF.glsl
@@ -1,24 +1,24 @@
-/**
+/** 
  * @file class1/deferred/skyF.glsl
  *
  * $LicenseInfo:firstyear=2005&license=viewerlgpl$
  * Second Life Viewer Source Code
  * Copyright (C) 2005, 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
  * $/LicenseInfo$
  */
@@ -27,6 +27,15 @@
 in vec3 vary_HazeColor;
 in float vary_LightNormPosDot;
 
+#ifdef HAS_HDRI
+in vec4 vary_position;
+in vec3 vary_rel_pos;
+uniform float sky_hdr_scale;
+uniform float hdri_split_screen;
+uniform mat3 env_mat;
+uniform sampler2D environmentMap;
+#endif
+
 uniform sampler2D rainbow_map;
 uniform sampler2D halo_map;
 
@@ -37,6 +46,9 @@ uniform float ice_level;
 out vec4 frag_data[4];
 
 vec3 srgb_to_linear(vec3 c);
+vec3 linear_to_srgb(vec3 c);
+
+#define PI 3.14159265
 
 /////////////////////////////////////////////////////////////////////////
 // The fragment shader for the sky
@@ -71,24 +83,42 @@ vec3 halo22(float d)
 
 void main()
 {
-    // Potential Fill-rate optimization.  Add cloud calculation
-    // back in and output alpha of 0 (so that alpha culling kills
-    // the fragment) if the sky wouldn't show up because the clouds
-    // are fully opaque.
-
-    vec3 color = vary_HazeColor;
-
-    float  rel_pos_lightnorm = vary_LightNormPosDot;
-    float optic_d = rel_pos_lightnorm;
-    vec3  halo_22 = halo22(optic_d);
-    color.rgb += rainbow(optic_d);
-    color.rgb += halo_22;
-    color.rgb *= 2.;
-    color.rgb = clamp(color.rgb, vec3(0), vec3(5));
+    vec3 color;
+#ifdef HAS_HDRI
+    vec3 frag_coord = vary_position.xyz/vary_position.w;
+    if (-frag_coord.x > ((1.0-hdri_split_screen)*2.0-1.0))
+    {
+        vec3 pos = normalize(vary_rel_pos);
+        pos = env_mat * pos;
+        vec2 texCoord = vec2(atan(pos.z, pos.x) + PI, acos(pos.y)) / vec2(2.0 * PI, PI);
+        color = textureLod(environmentMap, texCoord.xy, 0).rgb * sky_hdr_scale;
+        color = min(color, vec3(8192*8192*16)); // stupidly large value arrived at by binary search -- avoids framebuffer corruption from some HDRIs
+
+        frag_data[2] = vec4(0.0,0.0,0.0,GBUFFER_FLAG_HAS_HDRI);
+    }
+    else
+#endif
+    {
+        // Potential Fill-rate optimization.  Add cloud calculation 
+        // back in and output alpha of 0 (so that alpha culling kills 
+        // the fragment) if the sky wouldn't show up because the clouds 
+        // are fully opaque.
+
+        color = vary_HazeColor;
+
+        float  rel_pos_lightnorm = vary_LightNormPosDot;
+        float optic_d = rel_pos_lightnorm;
+        vec3  halo_22 = halo22(optic_d);
+        color.rgb += rainbow(optic_d);
+        color.rgb += halo_22;
+        color.rgb *= 2.;
+        color.rgb = clamp(color.rgb, vec3(0), vec3(5));
+
+        frag_data[2] = vec4(0.0,0.0,0.0,GBUFFER_FLAG_SKIP_ATMOS);
+    }
 
     frag_data[0] = vec4(0);
     frag_data[1] = vec4(0);
-    frag_data[2] = vec4(0.0,0.0,0.0,GBUFFER_FLAG_SKIP_ATMOS); //1.0 in norm.w masks off fog
     frag_data[3] = vec4(color.rgb, 1.0);
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/skyV.glsl b/indra/newview/app_settings/shaders/class1/deferred/skyV.glsl
index 6110b6ade0..24d2db2183 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/skyV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/skyV.glsl
@@ -35,6 +35,11 @@ in vec3 position;
 out vec3 vary_HazeColor;
 out float vary_LightNormPosDot;
 
+#ifdef HAS_HDRI
+out vec4 vary_position;
+out vec3 vary_rel_pos;
+#endif
+
 // Inputs
 uniform vec3 camPosLocal;
 
@@ -72,6 +77,11 @@ void main()
     // Get relative position
     vec3 rel_pos = position.xyz - camPosLocal.xyz + vec3(0, 50, 0);
 
+#ifdef HAS_HDRI
+    vary_rel_pos = rel_pos;
+    vary_position = pos;
+#endif
+
     // Adj position vector to clamp altitude
     if (rel_pos.y > 0.)
     {
@@ -92,13 +102,13 @@ void main()
 
     // Initialize temp variables
     vec3 sunlight = (sun_up_factor == 1) ? sunlight_color : moonlight_color * 0.7; //magic 0.7 to match legacy color
-
+    
     // Sunlight attenuation effect (hue and brightness) due to atmosphere
     // this is used later for sunlight modulation at various altitudes
     vec3 light_atten = (blue_density + vec3(haze_density * 0.25)) * (density_multiplier * max_y);
 
     // Calculate relative weights
-    vec3 combined_haze = abs(blue_density) + vec3(abs(haze_density));
+    vec3 combined_haze = max(abs(blue_density) + vec3(abs(haze_density)), vec3(1e-6));
     vec3 blue_weight   = blue_density / combined_haze;
     vec3 haze_weight   = haze_density / combined_haze;
 
@@ -142,7 +152,7 @@ void main()
     sunlight *= max(0.0, (1. - cloud_shadow));
 
     // Haze color below cloud
-    vec3 add_below_cloud = (blue_horizon * blue_weight * (sunlight + ambient)
+    vec3 add_below_cloud = (blue_horizon * blue_weight * (sunlight + ambient) 
                          + (haze_horizon * haze_weight) * (sunlight * haze_glow + ambient));
 
     // Attenuate cloud color by atmosphere
diff --git a/indra/newview/app_settings/shaders/class1/deferred/terrainF.glsl b/indra/newview/app_settings/shaders/class1/deferred/terrainF.glsl
index bee9e6d2fe..5f598f84a7 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/terrainF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/terrainF.glsl
@@ -1,28 +1,28 @@
-/**
+/** 
  * @file class1\deferred\terrainF.glsl
  *
  * $LicenseInfo:firstyear=2007&license=viewerlgpl$
  * Second Life Viewer Source Code
  * Copyright (C) 2007, 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]*/
 
 out vec4 frag_data[4];
@@ -38,12 +38,13 @@ in vec3 vary_normal;
 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);
     vec4 color1 = texture(detail_1, vary_texcoord0.xy);
     vec4 color2 = texture(detail_2, vary_texcoord0.xy);
@@ -53,13 +54,13 @@ void main()
     float alpha2 = texture(alpha_ramp,vary_texcoord1.xy).a;
     float alphaFinal = texture(alpha_ramp, vary_texcoord1.zw).a;
     vec4 outColor = mix( mix(color3, color2, alpha2), mix(color1, color0, alpha1), alphaFinal );
-
-    outColor.a = 0.0; // yes, downstream atmospherics
-
+   
+    outColor.a = 0.0; // yes, downstream atmospherics 
+    
     frag_data[0] = outColor;
     frag_data[1] = vec4(0.0,0.0,0.0,-1.0);
     vec3 nvn = normalize(vary_normal);
-    frag_data[2] = vec4(encode_normal(nvn.xyz), 0.0, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[2] = vec4(nvn.xyz, GBUFFER_FLAG_HAS_ATMOS);
     frag_data[3] = vec4(0);
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/terrainV.glsl b/indra/newview/app_settings/shaders/class1/deferred/terrainV.glsl
index aab2abff1e..b4ab7cd169 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/terrainV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/terrainV.glsl
@@ -1,36 +1,36 @@
-/**
+/** 
  * @file class1\environment\terrainV.glsl
  *
  * $LicenseInfo:firstyear=2007&license=viewerlgpl$
  * Second Life Viewer Source Code
  * Copyright (C) 2007, 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_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 +41,18 @@ 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.z = 0;
+    tcoord.w = 1;
 
-    tcoord = mat * tcoord;
-
-    return tcoord;
+    tcoord = mat * tcoord; 
+    
+    return tcoord.xy; 
 }
 
 void main()
@@ -62,15 +62,15 @@ 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);
-
+    
     vary_texcoord0.zw = t.xy;
     vary_texcoord1.xy = t.xy-vec2(2.0, 0.0);
     vary_texcoord1.zw = t.xy-vec2(1.0, 0.0);
diff --git a/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl b/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
index 8e641522e3..7c02cb9d4a 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
@@ -1,24 +1,24 @@
-/**
+/** 
  * @file class1/deferred/textureUtilV.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
  * $/LicenseInfo$
  */
@@ -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
@@ -77,6 +77,19 @@ vec2 texture_transform(vec2 vertex_texcoord, vec4[2] khr_gltf_transform, mat4 sl
     return texcoord;
 }
 
+// Similar to texture_transform but no offset during coordinate system
+// conversion, and no texture animation support.
+vec2 terrain_texture_transform(vec2 vertex_texcoord, vec4[2] khr_gltf_transform)
+{
+    vec2 texcoord = vertex_texcoord;
+
+    texcoord.y = -texcoord.y;
+    texcoord = khr_texture_transform(texcoord, khr_gltf_transform[0].xy, khr_gltf_transform[0].z, khr_gltf_transform[1].xy);
+    texcoord.y = -texcoord.y;
+
+    return texcoord;
+}
+
 // Take the rotation only from both transforms and apply to the tangent. This
 // accounts for the change of the topology of the normal texture when a texture
 // rotation is applied to it.
@@ -120,3 +133,25 @@ vec3 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] kh
 
     return (weights.x * vertex_binormal.xyz) + (weights.y * vertex_tangent.xyz);
 }
+
+// Similar to tangent_space_transform but no no texture animation support.
+vec3 terrain_tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform)
+{
+    // Immediately convert to left-handed coordinate system ((0,1) -> (0, -1))
+    vec2 weights = vec2(0, -1);
+
+    // Apply KHR_texture_transform (rotation only)
+    float khr_rotation = khr_gltf_transform[0].z;
+    mat2 khr_rotation_mat = mat2(
+        cos(khr_rotation),-sin(khr_rotation),
+        sin(khr_rotation), cos(khr_rotation)
+    );
+    weights = khr_rotation_mat * weights;
+
+    // Convert back to right-handed coordinate system
+    weights.y = -weights.y;
+
+    vec3 vertex_binormal = vertex_tangent.w * cross(vertex_normal, vertex_tangent.xyz);
+
+    return (weights.x * vertex_binormal.xyz) + (weights.y * vertex_tangent.xyz);
+}
diff --git a/indra/newview/app_settings/shaders/class1/deferred/treeF.glsl b/indra/newview/app_settings/shaders/class1/deferred/treeF.glsl
index db6070f328..05922ecb1a 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/treeF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/treeF.glsl
@@ -32,13 +32,14 @@ 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)
     {
@@ -48,6 +49,6 @@ void main()
     frag_data[0] = vec4(vertex_color.rgb*col.rgb, 0.0);
     frag_data[1] = vec4(0,0,0,0);
     vec3 nvn = normalize(vary_normal);
-    frag_data[2] = vec4(encode_normal(nvn.xyz), 0.0, GBUFFER_FLAG_HAS_ATMOS);
+    frag_data[2] = vec4(nvn.xyz, GBUFFER_FLAG_HAS_ATMOS);
     frag_data[3] = vec4(0);
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/treeV.glsl b/indra/newview/app_settings/shaders/class1/deferred/treeV.glsl
index 81900fba70..ef5602f1e5 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);