secondlife/viewer#1474: Remove small texture offset from PBR terrain

2 files changed, 42 insertions, 7 deletions

diff --git a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
index 489fc26e3f..d7c8fe1861 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/pbrterrainV.glsl
@@ -50,8 +50,8 @@ out vec3 vary_position;
 // tangent_space_transform below.
 uniform vec4[2] texture_base_color_transform;
 
-vec2 texture_transform(vec2 vertex_texcoord, vec4[2] khr_gltf_transform, mat4 sl_animation_transform);
-vec3 tangent_space_transform(vec4 vertex_tangent, vec3 vertex_normal, vec4[2] khr_gltf_transform, mat4 sl_animation_transform);
+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()
 {
@@ -70,7 +70,7 @@ void main()
     // *HACK: Should be using texture_normal_transform here. The KHR texture
     // transform spec requires handling texture transforms separately for each
     // individual texture.
-    vary_tangent = normalize(tangent_space_transform(vec4(t, tangent.w), n, texture_base_color_transform, texture_matrix0));
+    vary_tangent = normalize(terrain_tangent_space_transform(vec4(t, tangent.w), n, texture_base_color_transform));
     vary_sign = tangent.w;
     vary_normal = normalize(n);
 
@@ -80,13 +80,13 @@ void main()
     // separately for each individual texture.
 #if TERRAIN_PLANAR_TEXTURE_SAMPLE_COUNT == 3
     // xy
-    vary_coords[0].xy = texture_transform(position.xy, texture_base_color_transform, texture_matrix0);
+    vary_coords[0].xy = terrain_texture_transform(position.xy, texture_base_color_transform);
     // yz
-    vary_coords[0].zw = texture_transform(position.yz, texture_base_color_transform, texture_matrix0);
+    vary_coords[0].zw = terrain_texture_transform(position.yz, texture_base_color_transform);
     // (-x)z
-    vary_coords[1].xy = texture_transform(position.xz * vec2(-1, 1), texture_base_color_transform, texture_matrix0);
+    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 = texture_transform(position.xy, texture_base_color_transform, texture_matrix0);
+    vary_texcoord0.xy = terrain_texture_transform(position.xy, texture_base_color_transform);
 #endif
     
     vec4 tc = vec4(texcoord1,0,1);
diff --git a/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl b/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
index 732333311c..7c02cb9d4a 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/textureUtilV.glsl
@@ -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);
+}