SL-17703: PBR: Clamp roughness to minimum to match Blender, etc.

2 files changed, 17 insertions, 11 deletions

diff --git a/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl b/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
index 8a3eb39ae7..46463818f8 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
@@ -405,23 +405,31 @@ float V_GGX( float nl, float nv, float alphaRough )
     return 0.0;
 }
 
+// NOTE: Assumes a hard-coded IOR = 1.5
 void initMaterial( vec3 diffuse, vec3 packedORM, out float alphaRough, out vec3 c_diff, out vec3 reflect0, out vec3 reflect90, out float specWeight )
 {
     float metal      = packedORM.b;
-          c_diff     = mix(diffuse.rgb, vec3(0), metal);
+          c_diff     = mix(diffuse, vec3(0), metal);
     float IOR        = 1.5;                                // default Index Of Refraction 1.5 (dielectrics)
           reflect0   = vec3(0.04);                         // -> incidence reflectance 0.04
-          reflect0   = mix( reflect0, diffuse.rgb, metal); // reflect at 0 degrees
+//        reflect0   = vec3(calcF0(IOR));
+          reflect0   = mix(reflect0, diffuse, metal);      // reflect at 0 degrees
           reflect90  = vec3(1);                            // reflect at 90 degrees
           specWeight = 1.0;
 
-    float perceptualRough = packedORM.g;
-          alphaRough      = perceptualRough * perceptualRough;
+    // When roughness is zero blender shows a tiny specular
+    float perceptualRough = max(packedORM.g, 0.1);
+    alphaRough      = perceptualRough * perceptualRough;
+}
+
+vec3 BRDFDiffuse(vec3 color)
+{
+    return color / M_PI;
 }
 
 vec3 BRDFLambertian( vec3 reflect0, vec3 reflect90, vec3 c_diff, float specWeight, float vh )
 {
-    return (1.0 - specWeight * fresnelSchlick( reflect0, reflect90, vh)) * (c_diff / M_PI);
+    return (1.0 - specWeight * fresnelSchlick( reflect0, reflect90, vh)) * BRDFDiffuse(c_diff);
 }
 
 vec3 BRDFSpecularGGX( vec3 reflect0, vec3 reflect90, float alphaRough, float specWeight, float vh, float nl, float nv, float nh )
diff --git a/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl b/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
index dcb03642cd..5323159058 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
@@ -264,7 +264,6 @@ void main()
              packedORM        = vec3(1,1,1);
 #endif
         float IOR             = 1.5;         // default Index Of Refraction 1.5 (dielectrics)
-        vec3  reflect0        = vec3(0.04);  // -> incidence reflectance 0.04
 #if HAS_IOR
               reflect0        = vec3(calcF0(IOR));
 #endif
@@ -274,7 +273,6 @@ void main()
         float ao         = packedORM.r;
         float metal      = packedORM.b;
         vec3  c_diff     = mix(diffuse.rgb,vec3(0),metal);
-        vec3  reflect90  = vec3(0);
         vec3  v          = -normalize(pos.xyz);
 #if DEBUG_PBR_VERT2CAM1
               v = vec3(0,0,1);
@@ -292,11 +290,11 @@ void main()
         float dotBV = clamp(dot(b,v),0,1);
 
         // Reference: getMetallicRoughnessInfo
-        float perceptualRough = packedORM.g;
+        vec3  base            = linear_to_srgb(diffuse.rgb);
+        float perceptualRough = max(packedORM.g, 0.1);
         float alphaRough      = perceptualRough * perceptualRough;
-        vec3  colorDiff       = mix( diffuse.rgb, vec3(0)    , metal);
-              reflect0        = mix( reflect0   , diffuse.rgb, metal); // reflect at 0 degrees
-              reflect90       = vec3(1);                               // reflect at 90 degrees
+        vec3  reflect0        = mix(vec3(0.04), base, metal); // incidence reflectance 0.04 -> reflect at 0 degrees
+        vec3  reflect90       = vec3(1);                      // reflect at 90 degrees
 #if DEBUG_PBR_REFLECTANCE
         float reflectance     = max( max( reflect0.r, reflect0.g ), reflect0.b );
 #endif