SL-17701 WIP -- Correct color space management for base color and emissive...

SL-17701 WIP -- Correct color space management for base color and emissive color factors and textures.  Support for double sided alpha blended PBR materials.

indra/newview/app_settings/shaders/class1/deferred/pbralphaF.glsl

@@ -202,7 +202,7 @@ void main()
     }
 #endif
 
-    vec3 base = srgb_to_linear(vertex_color.rgb) * albedo.rgb;
+    vec3 base = vertex_color.rgb * albedo.rgb;
 
     vec4 norm = texture2D(bumpMap, vary_texcoord1.xy);
     norm.xyz = normalize(norm.xyz * 2 - 1);
@@ -212,6 +212,8 @@ void main()
                       dot(norm.xyz,vary_mat2));
 
     tnorm = normalize(tnorm.xyz);
+
+    tnorm *= gl_FrontFacing ? 1.0 : -1.0;
     norm.xyz = tnorm.xyz;
 
 #ifdef HAS_SHADOW
@@ -230,7 +232,9 @@ void main()
     packedORM.g *= roughnessFactor;
     packedORM.b *= metallicFactor;
 
-    vec3 colorEmissive = srgb_to_linear(emissiveColor);
+    // emissiveColor is the emissive color factor from GLTF and is already in linear space
+    vec3 colorEmissive = emissiveColor;
+    // emissiveMap here is a vanilla RGB texture encoded as sRGB, manually convert to linear
     colorEmissive *= srgb_to_linear(texture2D(emissiveMap, vary_texcoord0.xy).rgb);
 
     vec3 colorDiffuse     = vec3(0);

indra/newview/app_settings/shaders/class1/deferred/pbropaqueF.glsl

@@ -50,6 +50,7 @@ uniform float minimum_alpha; // PBR alphaMode: MASK, See: mAlphaCutoff, setAlpha
 
 vec2 encode_normal(vec3 n);
 vec3 linear_to_srgb(vec3 c);
+vec3 srgb_to_linear(vec3 c);
 
 uniform mat3 normal_matrix;
 
@@ -64,7 +65,7 @@ void main()
         discard;
     }
 
-    vec3 col = vertex_color.rgb * albedo.rgb;
+    vec3 col = vertex_color.rgb * srgb_to_linear(albedo.rgb);
 
     // from mikktspace.com
     vec3 vNt = texture2D(bumpMap, vary_texcoord1.xy).xyz*2.0-1.0;
@@ -86,7 +87,7 @@ void main()
     spec.b *= metallicFactor;
 
     vec3 emissive = emissiveColor;
-    emissive *= texture2D(emissiveMap, vary_texcoord0.xy).rgb;
+    emissive *= srgb_to_linear(texture2D(emissiveMap, vary_texcoord0.xy).rgb);
 
     tnorm *= gl_FrontFacing ? 1.0 : -1.0;
 
@@ -97,8 +98,8 @@ void main()
     //emissive = vNt * 0.5 + 0.5;
     //emissive = tnorm*0.5+0.5;
     // See: C++: addDeferredAttachments(), GLSL: softenLightF
-    frag_data[0] = vec4(col, 0.0);                                                   // Diffuse
-    frag_data[1] = vec4(emissive, vertex_color.a);                                   // PBR sRGB Emissive
+    frag_data[0] = vec4(linear_to_srgb(col), 0.0);                                                   // Diffuse
+    frag_data[1] = vec4(linear_to_srgb(emissive), vertex_color.a);                                   // PBR sRGB Emissive
     frag_data[2] = vec4(encode_normal(tnorm), vertex_color.a, GBUFFER_FLAG_HAS_PBR); // normal, environment intensity, flags
     frag_data[3] = vec4(spec.rgb,0);                                                 // PBR linear packed Occlusion, Roughness, Metal.
 }

indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl

@@ -131,7 +131,7 @@ void main()
     float light_gamma = 1.0 / 1.3;
 
     vec4 diffuse     = texture2DRect(diffuseRect, tc);
-    vec4 spec        = texture2DRect(specularRect, vary_fragcoord.xy); // NOTE: PBR sRGB Emissive
+    vec4 spec        = texture2DRect(specularRect, vary_fragcoord.xy); // NOTE: PBR linear Emissive
 
 #if defined(HAS_SUN_SHADOW) || defined(HAS_SSAO)
     vec2 scol_ambocc = texture2DRect(lightMap, vary_fragcoord.xy).rg;

indra/newview/lldrawpoolalpha.cpp

@@ -615,6 +615,8 @@ void LLDrawPoolAlpha::renderAlpha(U32 mask, bool depth_only, bool rigged)
                 LLGLTFMaterial *gltf_mat = params.mGLTFMaterial; // Also see: LLPipeline::getPoolTypeFromTE()
                 bool is_pbr = LLPipeline::sRenderPBR && gltf_mat;
 
+                LLGLDisable cull_face(is_pbr && gltf_mat->mDoubleSided ? GL_CULL_FACE : 0);
+
                 if (is_pbr && gltf_mat->mAlphaMode == LLGLTFMaterial::ALPHA_MODE_BLEND)
                 {
                     target_shader = &gDeferredPBRAlphaProgram;