Merge remote-tracking branch 'secondlife/release/2024.08-DeltaFPS' into 2024.08-DeltaFPS

9 files changed, 345 insertions, 67 deletions

diff --git a/indra/newview/app_settings/shaders/class1/deferred/normgenF.glsl b/indra/newview/app_settings/shaders/class1/deferred/normgenF.glsl
index 902746366d..607a8c6ef6 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/normgenF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/normgenF.glsl
@@ -25,24 +25,53 @@
 
 /*[EXTRA_CODE_HERE]*/
 
+
+
+// generate a normal map using an approximation of the old emboss bump map "brightness/darkness" technique
+// srcMap is a source color image, output should be a normal
+
 out vec4 frag_color;
 
-uniform sampler2D alphaMap;
+uniform sampler2D srcMap;
 
 in vec2 vary_texcoord0;
 
 uniform float stepX;
 uniform float stepY;
 uniform float norm_scale;
+uniform int bump_code;
+
+#define BE_BRIGHTNESS 1
+#define BE_DARKNESS 2
+
+// get luminance or inverse luminance depending on bump_code
+float getBumpValue(vec2 texcoord)
+{
+    vec3 c = texture(srcMap, texcoord).rgb;
+
+    vec3 WEIGHT = vec3(0.2995, 0.5875, 0.1145);
+
+    float l = dot(c, WEIGHT);
+
+    if (bump_code == BE_DARKNESS)
+    {
+        l = 1.0 - l;
+    }
+
+    return l;
+}
+
 
 void main()
 {
-    float c = texture(alphaMap, vary_texcoord0).r;
+    float c = getBumpValue(vary_texcoord0);
+
+    float scaler = 512.0;
 
-    vec3 right = vec3(norm_scale, 0, (texture(alphaMap, vary_texcoord0+vec2(stepX, 0)).r-c)*255);
-    vec3 left = vec3(-norm_scale, 0, (texture(alphaMap, vary_texcoord0-vec2(stepX, 0)).r-c)*255);
-    vec3 up = vec3(0, -norm_scale, (texture(alphaMap, vary_texcoord0-vec2(0, stepY)).r-c)*255);
-    vec3 down = vec3(0, norm_scale, (texture(alphaMap, vary_texcoord0+vec2(0, stepY)).r-c)*255);
+    vec3 right = vec3(norm_scale, 0, (getBumpValue(vary_texcoord0+vec2(stepX, 0))-c)*scaler);
+    vec3 left = vec3(-norm_scale, 0, (getBumpValue(vary_texcoord0-vec2(stepX, 0))-c)*scaler);
+    vec3 up = vec3(0, -norm_scale, (getBumpValue(vary_texcoord0-vec2(0, stepY))-c)*scaler);
+    vec3 down = vec3(0, norm_scale, (getBumpValue(vary_texcoord0+vec2(0, stepY))-c)*scaler);
 
     vec3 norm = cross(right, down) + cross(down, left) + cross(left,up) + cross(up, right);
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbralphaV.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbralphaV.glsl
index ae179d3f37..66adf50fa9 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbralphaV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbralphaV.glsl
@@ -69,7 +69,7 @@ flat out float vary_sign;
 out vec3 vary_normal;
 
 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);
+vec4 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform, mat4 sl_animation_transform);
 
 
 void main()
@@ -103,8 +103,9 @@ void main()
 
     n = normalize(n);
 
-    vary_tangent = normalize(tangent_space_transform(vec4(t, tangent.w), n, texture_normal_transform, texture_matrix0));
-    vary_sign = tangent.w;
+    vec4 transformed_tangent = tangent_space_transform(vec4(t, tangent.w), n, texture_normal_transform, texture_matrix0);
+    vary_tangent = normalize(transformed_tangent.xyz);
+    vary_sign = transformed_tangent.w;
     vary_normal = n;
 
     vertex_color = diffuse_color;
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl
index fd020afd57..0ad9bf5e4b 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbropaqueV.glsl
@@ -63,7 +63,7 @@ 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);
+vec4 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform, mat4 sl_animation_transform);
 
 void main()
 {
@@ -97,8 +97,9 @@ void main()
 
     n = normalize(n);
 
-    vary_tangent = normalize(tangent_space_transform(vec4(t, tangent.w), n, texture_normal_transform, texture_matrix0));
-    vary_sign = tangent.w;
+    vec4 transformed_tangent = tangent_space_transform(vec4(t, tangent.w), n, texture_normal_transform, texture_matrix0);
+    vary_tangent = normalize(transformed_tangent.xyz);
+    vary_sign = transformed_tangent.w;
     vary_normal = n;
 
     vertex_color = diffuse_color;
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainF.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainF.glsl
index 2cb7ff196b..410c447c64 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainF.glsl
@@ -30,6 +30,9 @@
 #define TERRAIN_PBR_DETAIL_NORMAL -2
 #define TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS -3
 
+#define TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE 0
+#define TERRAIN_PAINT_TYPE_PBR_PAINTMAP 1
+
 #if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
 #define TerrainCoord vec4[3]
 #elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
@@ -48,6 +51,7 @@ struct TerrainMix
 };
 
 TerrainMix get_terrain_mix_weights(float alpha1, float alpha2, float alphaFinal);
+TerrainMix get_terrain_usage_from_weight3(vec3 weight3);
 
 struct PBRMix
 {
@@ -75,6 +79,9 @@ PBRMix terrain_sample_and_multiply_pbr(
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
     , sampler2D tex_vNt
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+    , float transform_sign
+#endif
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
     , sampler2D tex_emissive
@@ -94,7 +101,11 @@ PBRMix mix_pbr(PBRMix mix1, PBRMix mix2, float mix2_weight);
 
 out vec4 frag_data[4];
 
+#if TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE
 uniform sampler2D alpha_ramp;
+#elif TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_PBR_PAINTMAP
+uniform sampler2D paint_map;
+#endif
 
 // https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#additional-textures
 uniform sampler2D detail_0_base_color;
@@ -130,19 +141,25 @@ uniform vec3[4] emissiveColors;
 #endif
 uniform vec4 minimum_alphas; // PBR alphaMode: MASK, See: mAlphaCutoff, setAlphaCutoff()
 
-#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
-in vec4[10] vary_coords;
-#elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
-in vec4[2] vary_coords;
-#endif
 in vec3 vary_position;
 in vec3 vary_normal;
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
 in vec3 vary_tangents[4];
-flat in float vary_sign;
+flat in float vary_signs[4];
 #endif
+
+// vary_texcoord* are used for terrain composition, vary_coords are used for terrain UVs
+#if TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE
 in vec4 vary_texcoord0;
 in vec4 vary_texcoord1;
+#elif TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_PBR_PAINTMAP
+in vec2 vary_texcoord;
+#endif
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+in vec4[10] vary_coords;
+#elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
+in vec4[2] vary_coords;
+#endif
 
 void mirrorClip(vec3 position);
 
@@ -150,11 +167,11 @@ float terrain_mix(TerrainMix tm, vec4 tms4);
 
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
 // from mikktspace.com
-vec3 mikktspace(vec3 vNt, vec3 vT)
+vec3 mikktspace(vec3 vNt, vec3 vT, float sign)
 {
     vec3 vN = vary_normal;
 
-    vec3 vB = vary_sign * cross(vN, vT);
+    vec3 vB = sign * cross(vN, vT);
     vec3 tnorm = normalize( vNt.x * vT + vNt.y * vB + vNt.z * vN );
 
     tnorm *= gl_FrontFacing ? 1.0 : -1.0;
@@ -168,11 +185,16 @@ void main()
     // Make sure we clip the terrain if we're in a mirror.
     mirrorClip(vary_position);
 
+    TerrainMix tm;
+#if TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE
     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);
+    tm = get_terrain_mix_weights(alpha1, alpha2, alphaFinal);
+#elif TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_PBR_PAINTMAP
+    tm = get_terrain_usage_from_weight3(texture(paint_map, vary_texcoord).xyz);
+#endif
 
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_OCCLUSION)
     // RGB = Occlusion, Roughness, Metal
@@ -216,6 +238,9 @@ void main()
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
             , detail_0_normal
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+            , vary_signs[0]
+#endif
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
             , detail_0_emissive
@@ -231,7 +256,7 @@ void main()
 #endif
         );
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
-        mix2.vNt = mikktspace(mix2.vNt, vary_tangents[0]);
+        mix2.vNt = mikktspace(mix2.vNt, vary_tangents[0], vary_signs[0]);
 #endif
         pbr_mix = mix_pbr(pbr_mix, mix2, tm.weight.x);
         break;
@@ -258,6 +283,9 @@ void main()
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
             , detail_1_normal
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+            , vary_signs[1]
+#endif
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
             , detail_1_emissive
@@ -273,7 +301,7 @@ void main()
 #endif
         );
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
-        mix2.vNt = mikktspace(mix2.vNt, vary_tangents[1]);
+        mix2.vNt = mikktspace(mix2.vNt, vary_tangents[1], vary_signs[1]);
 #endif
         pbr_mix = mix_pbr(pbr_mix, mix2, tm.weight.y);
         break;
@@ -300,6 +328,9 @@ void main()
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
             , detail_2_normal
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+            , vary_signs[2]
+#endif
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
             , detail_2_emissive
@@ -315,7 +346,7 @@ void main()
 #endif
         );
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
-        mix2.vNt = mikktspace(mix2.vNt, vary_tangents[2]);
+        mix2.vNt = mikktspace(mix2.vNt, vary_tangents[2], vary_signs[2]);
 #endif
         pbr_mix = mix_pbr(pbr_mix, mix2, tm.weight.z);
         break;
@@ -342,6 +373,9 @@ void main()
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
             , detail_3_normal
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+            , vary_signs[3]
+#endif
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
             , detail_3_emissive
@@ -357,7 +391,7 @@ void main()
 #endif
         );
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
-        mix2.vNt = mikktspace(mix2.vNt, vary_tangents[3]);
+        mix2.vNt = mikktspace(mix2.vNt, vary_tangents[3], vary_signs[3]);
 #endif
         pbr_mix = mix_pbr(pbr_mix, mix2, tm.weight.w);
         break;
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainUtilF.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainUtilF.glsl
index d1a380bf94..fb4b139662 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainUtilF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainUtilF.glsl
@@ -51,7 +51,12 @@
 #define TERRAIN_PBR_DETAIL_NORMAL -2
 #define TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS -3
 
+#define TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE 0
+#define TERRAIN_PAINT_TYPE_PBR_PAINTMAP 1
+
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
 in vec3 vary_vertex_normal;
+#endif
 
 vec3 srgb_to_linear(vec3 c);
 
@@ -202,6 +207,45 @@ TerrainMix get_terrain_mix_weights(float alpha1, float alpha2, float alphaFinal)
     return tm;
 }
 
+// A paintmap weight applier for 4 swatches. The input saves a channel by not
+// storing swatch 1, and assuming the weights of the 4 swatches add to 1.
+// The components of weight3 should be between 0 and 1
+// The sum of the components of weight3 should be between 0 and 1
+TerrainMix get_terrain_usage_from_weight3(vec3 weight3)
+{
+    // These steps ensure the output weights add to between 0 and 1
+    weight3.xyz = max(vec3(0.0), weight3.xyz);
+    weight3.xyz /= max(1.0, weight3.x + weight3.y + weight3.z);
+
+    TerrainMix tm;
+
+    // Extract the first weight from the other weights
+    tm.weight.x = 1.0 - (weight3.x + weight3.y + weight3.z);
+    tm.weight.yzw = weight3.xyz;
+    ivec4 usage = max(ivec4(0), ivec4(ceil(tm.weight)));
+
+    tm.type = (usage.x * MIX_X) |
+              (usage.y * MIX_Y) |
+              (usage.z * MIX_Z) |
+              (usage.w * MIX_W);
+    return tm;
+}
+
+// Inverse of get_terrain_usage_from_weight3, excluding usage flags
+// The components of weight should be between 0 and 1
+// The sum of the components of weight should be 1
+vec3 get_weight3_from_terrain_weight(vec4 weight)
+{
+    // These steps ensure the input weights add to 1
+    weight = max(vec4(0.0), weight);
+    weight.x += 1.0 - sign(weight.x + weight.y + weight.z + weight.w);
+    weight /= weight.x + weight.y + weight.z + weight.w;
+
+    // Then return the input weights with the first weight truncated
+    return weight.yzw;
+}
+
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
 TerrainTriplanar _t_triplanar()
 {
     float sharpness = TERRAIN_TRIPLANAR_BLEND_FACTOR;
@@ -219,6 +263,8 @@ TerrainTriplanar _t_triplanar()
               ((usage.z) * SAMPLE_Z);
     return tw;
 }
+#endif
+
 
 // Assume weights add to 1
 float terrain_mix(TerrainMix tm, vec4 tms4)
@@ -256,11 +302,12 @@ vec3 _t_normal_post_1(vec3 vNt0, float sign_or_zero)
 }
 
 // Triplanar-specific normal texture fixes
-vec3 _t_normal_post_x(vec3 vNt0)
+vec3 _t_normal_post_x(vec3 vNt0, float tangent_sign)
 {
     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);
+    vNt_x.xy *= tangent_sign;
     return vNt_x;
 }
 vec3 _t_normal_post_y(vec3 vNt0)
@@ -285,6 +332,7 @@ PBRMix terrain_sample_pbr(
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
     , sampler2D tex_vNt
+    , float tangent_sign
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
     , sampler2D tex_emissive
@@ -314,7 +362,7 @@ PBRMix terrain_sample_pbr(
             );
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
         // Triplanar-specific normal texture fix
-        mix_x.vNt = _t_normal_post_x(mix_x.vNt);
+        mix_x.vNt = _t_normal_post_x(mix_x.vNt, tangent_sign);
 #endif
         mix = mix_pbr(mix, mix_x, tw.weight.x);
         break;
@@ -420,6 +468,9 @@ PBRMix terrain_sample_and_multiply_pbr(
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
     , sampler2D tex_vNt
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+    , float tangent_sign
+#endif
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
     , sampler2D tex_emissive
@@ -446,6 +497,9 @@ PBRMix terrain_sample_and_multiply_pbr(
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
         , tex_vNt
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+        , tangent_sign
+#endif
 #endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_EMISSIVE)
         , tex_emissive
diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
index f8e826bbdb..6791a22a76 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
@@ -28,31 +28,47 @@
 #define TERRAIN_PBR_DETAIL_NORMAL -2
 #define TERRAIN_PBR_DETAIL_METALLIC_ROUGHNESS -3
 
+#define TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE 0
+#define TERRAIN_PAINT_TYPE_PBR_PAINTMAP 1
+
 uniform mat3 normal_matrix;
 uniform mat4 texture_matrix0;
 uniform mat4 modelview_matrix;
 uniform mat4 modelview_projection_matrix;
+#if TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_PBR_PAINTMAP
+uniform float region_scale;
+#endif
 
 in vec3 position;
 in vec3 normal;
 in vec4 tangent;
 in vec4 diffuse_color;
+#if TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE
 in vec2 texcoord1;
+#endif
 
-out vec3 vary_vertex_normal; // Used by pbrterrainUtilF.glsl
+out vec3 vary_position;
 out vec3 vary_normal;
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
+out vec3 vary_vertex_normal; // Used by pbrterrainUtilF.glsl
+#endif
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
 out vec3 vary_tangents[4];
-flat out float vary_sign;
+flat out float vary_signs[4];
 #endif
+
+// vary_texcoord* are used for terrain composition, vary_coords are used for terrain UVs
+#if TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE
 out vec4 vary_texcoord0;
 out vec4 vary_texcoord1;
+#elif TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_PBR_PAINTMAP
+out vec2 vary_texcoord;
+#endif
 #if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
 out vec4[10] vary_coords;
 #elif TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 1
 out vec4[2] vary_coords;
 #endif
-out vec3 vary_position;
 
 // *HACK: Each material uses only one texture transform, but the KHR texture
 // transform spec allows handling texture transforms separately for each
@@ -60,7 +76,7 @@ out vec3 vary_position;
 uniform vec4[5] terrain_texture_transforms;
 
 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);
+vec4 terrain_tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform);
 
 void main()
 {
@@ -69,43 +85,52 @@ void main()
     vary_position = (modelview_matrix*vec4(position.xyz, 1.0)).xyz;
 
     vec3 n = normal_matrix * normal;
+#if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
     vary_vertex_normal = normal;
+#endif
     vec3 t = normal_matrix * tangent.xyz;
 
 #if (TERRAIN_PBR_DETAIL >= TERRAIN_PBR_DETAIL_NORMAL)
     {
         vec4[2] ttt;
+        vec4 transformed_tangent;
         // material 1
         ttt[0].xyz = terrain_texture_transforms[0].xyz;
         ttt[1].x = terrain_texture_transforms[0].w;
         ttt[1].y = terrain_texture_transforms[1].x;
-        vary_tangents[0] = normalize(terrain_tangent_space_transform(vec4(t, tangent.w), n, ttt));
+        transformed_tangent = terrain_tangent_space_transform(vec4(t, tangent.w), n, ttt);
+        vary_tangents[0] = normalize(transformed_tangent.xyz);
+        vary_signs[0] = transformed_tangent.w;
         // material 2
         ttt[0].xyz = terrain_texture_transforms[1].yzw;
         ttt[1].xy = terrain_texture_transforms[2].xy;
-        vary_tangents[1] = normalize(terrain_tangent_space_transform(vec4(t, tangent.w), n, ttt));
+        transformed_tangent = terrain_tangent_space_transform(vec4(t, tangent.w), n, ttt);
+        vary_tangents[1] = normalize(transformed_tangent.xyz);
+        vary_signs[1] = transformed_tangent.w;
         // material 3
         ttt[0].xy = terrain_texture_transforms[2].zw;
         ttt[0].z = terrain_texture_transforms[3].x;
         ttt[1].xy = terrain_texture_transforms[3].yz;
-        vary_tangents[2] = normalize(terrain_tangent_space_transform(vec4(t, tangent.w), n, ttt));
+        transformed_tangent = terrain_tangent_space_transform(vec4(t, tangent.w), n, ttt);
+        vary_tangents[2] = normalize(transformed_tangent.xyz);
+        vary_signs[2] = transformed_tangent.w;
         // material 4
         ttt[0].x = terrain_texture_transforms[3].w;
         ttt[0].yz = terrain_texture_transforms[4].xy;
         ttt[1].xy = terrain_texture_transforms[4].zw;
-        vary_tangents[3] = normalize(terrain_tangent_space_transform(vec4(t, tangent.w), n, ttt));
+        transformed_tangent = terrain_tangent_space_transform(vec4(t, tangent.w), n, ttt);
+        vary_tangents[3] = normalize(transformed_tangent.xyz);
+        vary_signs[3] = transformed_tangent.w;
     }
-
-    vary_sign = tangent.w;
 #endif
     vary_normal = normalize(n);
 
     // Transform and pass tex coords
     {
         vec4[2] ttt;
+#define transform_xy()             terrain_texture_transform(position.xy,               ttt)
 #if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
 // Don't care about upside-down (transform_xy_flipped())
-#define transform_xy()             terrain_texture_transform(position.xy,               ttt)
 #define transform_yz()             terrain_texture_transform(position.yz,               ttt)
 #define transform_negx_z()         terrain_texture_transform(position.xz * vec2(-1, 1), ttt)
 #define transform_yz_flipped()     terrain_texture_transform(position.yz * vec2(-1, 1), ttt)
@@ -150,26 +175,30 @@ void main()
         ttt[0].xyz = terrain_texture_transforms[0].xyz;
         ttt[1].x = terrain_texture_transforms[0].w;
         ttt[1].y = terrain_texture_transforms[1].x;
-        vary_coords[0].xy = terrain_texture_transform(position.xy, ttt);
+        vary_coords[0].xy = transform_xy();
         // material 2
         ttt[0].xyz = terrain_texture_transforms[1].yzw;
         ttt[1].xy = terrain_texture_transforms[2].xy;
-        vary_coords[0].zw = terrain_texture_transform(position.xy, ttt);
+        vary_coords[0].zw = transform_xy();
         // material 3
         ttt[0].xy = terrain_texture_transforms[2].zw;
         ttt[0].z = terrain_texture_transforms[3].x;
         ttt[1].xy = terrain_texture_transforms[3].yz;
-        vary_coords[1].xy = terrain_texture_transform(position.xy, ttt);
+        vary_coords[1].xy = transform_xy();
         // material 4
         ttt[0].x = terrain_texture_transforms[3].w;
         ttt[0].yz = terrain_texture_transforms[4].xy;
         ttt[1].xy = terrain_texture_transforms[4].zw;
-        vary_coords[1].zw = terrain_texture_transform(position.xy, ttt);
+        vary_coords[1].zw = transform_xy();
 #endif
     }
 
-    vec4 tc = vec4(texcoord1,0,1);
+#if TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_HEIGHTMAP_WITH_NOISE
+    vec2 tc = texcoord1.xy;
     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);
+#elif TERRAIN_PAINT_TYPE == TERRAIN_PAINT_TYPE_PBR_PAINTMAP
+    vary_texcoord = position.xy / region_scale;
+#endif
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl b/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
index 767416d564..c75a0e0d5d 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
@@ -94,36 +94,48 @@ vec2 terrain_texture_transform(vec2 vertex_texcoord, vec4[2] khr_gltf_transform)
 // 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.
+// In practice, this applies the inverse of the texture transform to the tangent.
+// It is effectively an inverse of the rotation
 // *HACK: Assume the imported GLTF model did not have both normal texture
 // transforms and tangent vertices. The use of this function is inconsistent
 // with the GLTF sample viewer when that is the case. See getNormalInfo in
 // https://raw.githubusercontent.com/KhronosGroup/glTF-Sample-Viewer/47a191931461a6f2e14de48d6da0f0eb6ec2d147/source/Renderer/shaders/material_info.glsl
 // We may want to account for this case during GLTF model import.
 // -Cosmic,2023-06-06
-vec3 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform, mat4 sl_animation_transform)
+vec4 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform, mat4 sl_animation_transform)
 {
-    vec2 weights = vec2(0, 1);
-
-    // Apply texture animation first to avoid shearing and other artifacts (rotation only)
-    mat2 sl_rot_scale;
-    sl_rot_scale[0][0] = sl_animation_transform[0][0];
-    sl_rot_scale[0][1] = sl_animation_transform[0][1];
-    sl_rot_scale[1][0] = sl_animation_transform[1][0];
-    sl_rot_scale[1][1] = sl_animation_transform[1][1];
-    weights = sl_rot_scale * weights;
-    // Remove scale
-    weights = normalize(weights);
-
-    // Convert to left-handed coordinate system
-    weights.y = -weights.y;
+    // Immediately convert to left-handed coordinate system, but it has no
+    // effect here because y is 0 ((1,0) -> (1,0))
+    vec2 weights = vec2(1, 0);
 
-    // Apply KHR_texture_transform (rotation only)
-    float khr_rotation = khr_gltf_transform[0].z;
+    // Apply inverse KHR_texture_transform (rotation and scale sign 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;
+    vec2 khr_scale_sign = sign(khr_gltf_transform[0].xy);
+    weights *= khr_scale_sign.xy;
+
+    // *NOTE: Delay conversion to right-handed coordinate system here, to
+    // remove the need for computing the inverse of the SL texture animation
+    // matrix.
+
+    // Apply texture animation last to avoid shearing and other artifacts (rotation only)
+    mat2 inv_sl_rot_scale;
+    inv_sl_rot_scale[0][0] = sl_animation_transform[0][0];
+    inv_sl_rot_scale[0][1] = sl_animation_transform[0][1];
+    inv_sl_rot_scale[1][0] = sl_animation_transform[1][0];
+    inv_sl_rot_scale[1][1] = sl_animation_transform[1][1];
+    weights = inv_sl_rot_scale * weights;
+    // *NOTE: Scale to be removed later
+
+    // Set weights to default if 0 for some reason
+    weights.x += 1.0 - abs(sign(sign(weights.x) + (0.5 * sign(weights.y))));
+
+    // Remove scale from SL texture animation transform
+    weights = normalize(weights);
 
     // Convert back to right-handed coordinate system
     weights.y = -weights.y;
@@ -132,27 +144,41 @@ vec3 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] kh
     // from the normal and tangent, as seen in the fragment shader
     vec3 vertex_binormal = vertex_tangent.w * cross(vertex_normal, vertex_tangent.xyz);
 
-    return (weights.x * vertex_binormal.xyz) + (weights.y * vertex_tangent.xyz);
+    // An additional sign flip prevents the binormal from being flipped as a
+    // result of a propagation of the tangent sign during the cross product.
+    float sign_flip = khr_scale_sign.x * khr_scale_sign.y;
+    return vec4((weights.x * vertex_tangent.xyz) + (weights.y * vertex_binormal.xyz), vertex_tangent.w * sign_flip);
 }
 
 // Similar to tangent_space_transform but no texture animation support.
-vec3 terrain_tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform)
+vec4 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);
+    // Immediately convert to left-handed coordinate system, but it has no
+    // effect here because y is 0 ((1,0) -> (1,0))
+    vec2 weights = vec2(1, 0);
 
-    // Apply KHR_texture_transform (rotation only)
-    float khr_rotation = khr_gltf_transform[0].z;
+    // Apply inverse KHR_texture_transform (rotation and scale sign 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;
+    vec2 khr_scale_sign = sign(khr_gltf_transform[0].xy);
+    weights *= khr_scale_sign.xy;
+
+    // Set weights to default if 0 for some reason
+    weights.x += 1.0 - abs(sign(sign(weights.x) + (0.5 * sign(weights.y))));
 
     // Convert back to right-handed coordinate system
     weights.y = -weights.y;
 
+    // Similar to the MikkTSpace-compatible method of extracting the binormal
+    // from the normal and tangent, as seen in the fragment shader
     vec3 vertex_binormal = vertex_tangent.w * cross(vertex_normal, vertex_tangent.xyz);
 
-    return (weights.x * vertex_binormal.xyz) + (weights.y * vertex_tangent.xyz);
+    // An additional sign flip prevents the binormal from being flipped as a
+    // result of a propagation of the tangent sign during the cross product.
+    float sign_flip = khr_scale_sign.x * khr_scale_sign.y;
+    return vec4((weights.x * vertex_tangent.xyz) + (weights.y * vertex_binormal.xyz), vertex_tangent.w * sign_flip);
 }
diff --git a/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeF.glsl b/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeF.glsl
new file mode 100644
index 0000000000..cf20653a0f
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeF.glsl
@@ -0,0 +1,62 @@
+/**
+ * @file terrainBakeF.glsl
+ *
+ * $LicenseInfo:firstyear=2007&license=viewerlgpl$
+ * 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
+ * $/LicenseInfo$
+ */
+
+/*[EXTRA_CODE_HERE]*/
+
+out vec4 frag_color;
+
+struct TerrainMix
+{
+    vec4 weight;
+    int type;
+};
+
+TerrainMix get_terrain_mix_weights(float alpha1, float alpha2, float alphaFinal);
+
+uniform sampler2D alpha_ramp;
+
+// vary_texcoord* are used for terrain composition
+in vec4 vary_texcoord0;
+in vec4 vary_texcoord1;
+
+void main()
+{
+    TerrainMix tm;
+    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;
+
+    tm = get_terrain_mix_weights(alpha1, alpha2, alphaFinal);
+
+    // tm.weight.x can be ignored. The paintmap saves a channel by not storing
+    // swatch 1, and assuming the weights of the 4 swatches add to 1.
+    // TERRAIN_PAINT_PRECISION emulates loss of precision at lower bit depth
+    // when a corresponding low-bit image format is not available. Because
+    // integral values at one depth cannot be precisely represented at another
+    // bit depth, rounding is required. To maximize numerical stability for
+    // future conversions, bit depth conversions should round to the nearest
+    // integer, not floor or ceil.
+    frag_color = max(vec4(round(tm.weight.yzw * TERRAIN_PAINT_PRECISION) / TERRAIN_PAINT_PRECISION, 1.0), vec4(0));
+}
diff --git a/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeV.glsl b/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeV.glsl
new file mode 100644
index 0000000000..fd150b54ad
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeV.glsl
@@ -0,0 +1,42 @@
+/**
+ * @file pbrTerrainBakeV.glsl
+ *
+ * $LicenseInfo:firstyear=2007&license=viewerlgpl$
+ * 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
+ * $/LicenseInfo$
+ */
+
+uniform mat4 modelview_projection_matrix;
+
+in vec3 position;
+in vec2 texcoord1;
+
+out vec4 vary_texcoord0;
+out vec4 vary_texcoord1;
+
+void main()
+{
+    gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0);
+    vec2 tc = texcoord1.xy;
+    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);
+}
+