Merge pull request #464 from Unity-Technologies/Update-detail-texture-blend-formula

Update detail textures blend formula

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLit.shader

         _DetailMap2("DetailMap2", 2D) = "black" {}
         _DetailMap3("DetailMap3", 2D) = "black" {}
 
-        _DetailAlbedoScale0("_DetailAlbedoScale0", Range(-2.0, 2.0)) = 1
-        _DetailAlbedoScale1("_DetailAlbedoScale1", Range(-2.0, 2.0)) = 1
-        _DetailAlbedoScale2("_DetailAlbedoScale2", Range(-2.0, 2.0)) = 1
-        _DetailAlbedoScale3("_DetailAlbedoScale3", Range(-2.0, 2.0)) = 1
+        _DetailAlbedoScale0("_DetailAlbedoScale0", Range(0.0, 2.0)) = 1
+        _DetailAlbedoScale1("_DetailAlbedoScale1", Range(0.0, 2.0)) = 1
+        _DetailAlbedoScale2("_DetailAlbedoScale2", Range(0.0, 2.0)) = 1
+        _DetailAlbedoScale3("_DetailAlbedoScale3", Range(0.0, 2.0)) = 1
 
         _DetailNormalScale0("_DetailNormalScale0", Range(0.0, 2.0)) = 1
         _DetailNormalScale1("_DetailNormalScale1", Range(0.0, 2.0)) = 1
-        _DetailSmoothnessScale0("_DetailSmoothnessScale0", Range(-2.0, 2.0)) = 1
-        _DetailSmoothnessScale1("_DetailSmoothnessScale1", Range(-2.0, 2.0)) = 1
-        _DetailSmoothnessScale2("_DetailSmoothnessScale2", Range(-2.0, 2.0)) = 1
-        _DetailSmoothnessScale3("_DetailSmoothnessScale3", Range(-2.0, 2.0)) = 1
+        _DetailSmoothnessScale0("_DetailSmoothnessScale0", Range(0.0, 2.0)) = 1
+        _DetailSmoothnessScale1("_DetailSmoothnessScale1", Range(0.0, 2.0)) = 1
+        _DetailSmoothnessScale2("_DetailSmoothnessScale2", Range(0.0, 2.0)) = 1
+        _DetailSmoothnessScale3("_DetailSmoothnessScale3", Range(0.0, 2.0)) = 1
 
         [Enum(TangentSpace, 0, ObjectSpace, 1)] _NormalMapSpace0("NormalMap space", Float) = 0
         [Enum(TangentSpace, 0, ObjectSpace, 1)] _NormalMapSpace1("NormalMap space", Float) = 0

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLitTessellation.shader

         _DetailMap2("DetailMap2", 2D) = "black" {}
         _DetailMap3("DetailMap3", 2D) = "black" {}
 
-        _DetailAlbedoScale0("_DetailAlbedoScale0", Range(-2.0, 2.0)) = 1
-        _DetailAlbedoScale1("_DetailAlbedoScale1", Range(-2.0, 2.0)) = 1
-        _DetailAlbedoScale2("_DetailAlbedoScale2", Range(-2.0, 2.0)) = 1
-        _DetailAlbedoScale3("_DetailAlbedoScale3", Range(-2.0, 2.0)) = 1
+        _DetailAlbedoScale0("_DetailAlbedoScale0", Range(0.0, 2.0)) = 1
+        _DetailAlbedoScale1("_DetailAlbedoScale1", Range(0.0, 2.0)) = 1
+        _DetailAlbedoScale2("_DetailAlbedoScale2", Range(0.0, 2.0)) = 1
+        _DetailAlbedoScale3("_DetailAlbedoScale3", Range(0.0, 2.0)) = 1
 
         _DetailNormalScale0("_DetailNormalScale0", Range(0.0, 2.0)) = 1
         _DetailNormalScale1("_DetailNormalScale1", Range(0.0, 2.0)) = 1
-        _DetailSmoothnessScale0("_DetailSmoothnessScale0", Range(-2.0, 2.0)) = 1
-        _DetailSmoothnessScale1("_DetailSmoothnessScale1", Range(-2.0, 2.0)) = 1
-        _DetailSmoothnessScale2("_DetailSmoothnessScale2", Range(-2.0, 2.0)) = 1
-        _DetailSmoothnessScale3("_DetailSmoothnessScale3", Range(-2.0, 2.0)) = 1
+        _DetailSmoothnessScale0("_DetailSmoothnessScale0", Range(0.0, 2.0)) = 1
+        _DetailSmoothnessScale1("_DetailSmoothnessScale1", Range(0.0, 2.0)) = 1
+        _DetailSmoothnessScale2("_DetailSmoothnessScale2", Range(0.0, 2.0)) = 1
+        _DetailSmoothnessScale3("_DetailSmoothnessScale3", Range(0.0, 2.0)) = 1
 
         [Enum(TangentSpace, 0, ObjectSpace, 1)] _NormalMapSpace0("NormalMap space", Float) = 0
         [Enum(TangentSpace, 0, ObjectSpace, 1)] _NormalMapSpace1("NormalMap space", Float) = 0

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.shader

         _HeightCenter("Height Center", Range(0.0, 1.0)) = 0.5 // In texture space
 
         _DetailMap("DetailMap", 2D) = "black" {}
-        _DetailAlbedoScale("_DetailAlbedoScale", Range(-2.0, 2.0)) = 1
+        _DetailAlbedoScale("_DetailAlbedoScale", Range(0.0, 2.0)) = 1
-        _DetailSmoothnessScale("_DetailSmoothnessScale", Range(-2.0, 2.0)) = 1
+        _DetailSmoothnessScale("_DetailSmoothnessScale", Range(0.0, 2.0)) = 1
 
         _TangentMap("TangentMap", 2D) = "bump" {}
         _TangentMapOS("TangentMapOS", 2D) = "white" {}

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitDataInternal.hlsl

-void ADD_IDX(ComputeLayerTexCoord)( // Uv related parameters
+void ADD_IDX(ComputeLayerTexCoord)( // Uv related parameters
                                     float2 texCoord0, float2 texCoord1, float2 texCoord2, float2 texCoord3, float4 uvMappingMask, float4 uvMappingMaskDetails,
                                     // scale and bias for base and detail + global tiling factor (for layered lit only)
                                     float2 texScale, float2 texBias, float2 texScaleDetails, float2 texBiasDetails, float additionalTiling,
 
     surfaceData.baseColor = SAMPLE_UVMAPPING_TEXTURE2D(ADD_IDX(_BaseColorMap), ADD_ZERO_IDX(sampler_BaseColorMap), ADD_IDX(layerTexCoord.base)).rgb * ADD_IDX(_BaseColor).rgb;
 #ifdef _DETAIL_MAP_IDX
-    surfaceData.baseColor *= LerpWhiteTo(2.0 * detailAlbedo, detailMask * ADD_IDX(_DetailAlbedoScale));
-    // we saturate to avoid to have a smoothness value above 1
-    surfaceData.baseColor = saturate(surfaceData.baseColor);
+    // Use overlay blend mode for detail abledo: (base < 0.5 ? (2.0 * base * blend) : (1.0 - 2.0 * (1.0 - base) * (1.0 - blend)))
+    float baseColorOverlay = (detailAlbedo < 0.5) ? 
+                                surfaceData.baseColor * PositivePow(2.0 * detailAlbedo, ADD_IDX(_DetailAlbedoScale)) :
+                                1.0 - 2.0 * (1.0 - surfaceData.baseColor) * (1.0 - (detailAlbedo * ADD_IDX(_DetailAlbedoScale)));
+    // Lerp with details mask
+    surfaceData.baseColor = lerp(surfaceData.baseColor, saturate(baseColorOverlay), detailMask);
 #endif
 
     surfaceData.specularOcclusion = 1.0; // Will be setup outside of this function
 #endif
 
 #ifdef _DETAIL_MAP_IDX
-    surfaceData.perceptualSmoothness *= LerpWhiteTo(2.0 * detailSmoothness, detailMask * ADD_IDX(_DetailSmoothnessScale));
-    // we saturate to avoid to have a smoothness value above 1
-    surfaceData.perceptualSmoothness = saturate(surfaceData.perceptualSmoothness);
+    // Use overlay blend mode for detail abledo: (base < 0.5 ? (2.0 * base * blend) : (1.0 - 2.0 * (1.0 - base) * (1.0 - blend)))
+    float smoothnessOverlay = (detailSmoothness < 0.5) ?
+                                surfaceData.perceptualSmoothness * PositivePow(2.0 * detailSmoothness, ADD_IDX(_DetailSmoothnessScale)) :
+                                1.0 - 2.0 * (1.0 - surfaceData.baseColor) * (1.0 - (detailSmoothness * ADD_IDX(_DetailSmoothnessScale)));
+    // Lerp with details mask
+    surfaceData.perceptualSmoothness = lerp(surfaceData.perceptualSmoothness, saturate(smoothnessOverlay), detailMask);
 #endif
 
     // MaskMap is RGBA: Metallic, Ambient Occlusion (Optional), emissive Mask (Optional), Smoothness

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitTessellation.shader

         _HeightMax("Heightmap Max", Float) = 1
 
         _DetailMap("DetailMap", 2D) = "black" {}
-        _DetailAlbedoScale("_DetailAlbedoScale", Range(-2.0, 2.0)) = 1
+        _DetailAlbedoScale("_DetailAlbedoScale", Range(0.0, 2.0)) = 1
-        _DetailSmoothnessScale("_DetailSmoothnessScale", Range(-2.0, 2.0)) = 1
+        _DetailSmoothnessScale("_DetailSmoothnessScale", Range(0.0, 2.0)) = 1
 
         _TangentMap("TangentMap", 2D) = "bump" {}
         _TangentMapOS("TangentMapOS", 2D) = "white" {}