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Assets/Alloy/Shaders/Feature/Decal.cginc

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+// Alloy Physical Shader Framework
+// Copyright 2013-2017 RUST LLC.
+// http://www.alloy.rustltd.com/
+
+/////////////////////////////////////////////////////////////////////////////////
+/// @file Decal.cginc
+/// @brief Handles vertex-weighted alpha-blended decals.
+/////////////////////////////////////////////////////////////////////////////////
+
+#ifndef ALLOY_SHADERS_FEATURE_DECAL_CGINC
+#define ALLOY_SHADERS_FEATURE_DECAL_CGINC
+
+#if !defined(A_DECAL_ON) && defined(_DECAL_ON)
+    #define A_DECAL_ON
+#endif
+
+#include "Assets/Alloy/Shaders/Framework/Feature.cginc"
+
+#ifdef A_DECAL_ON
+    /// The decal tint color.
+    /// Expects a linear LDR color with alpha.
+    half4 _DecalColor;
+    
+    /// Decal texture.
+    /// Expects an RGBA map with sRGB sampling.
+    A_SAMPLER_2D(_DecalTex);
+    
+    /// Weight of the decal effect.
+    /// Expects values in the range [0,1].
+    half _DecalWeight;
+        
+    /// The specularity that will be applied over the decal.
+    /// Expects values in the range [0,1].
+    half _DecalSpecularity;
+    
+    /// Toggles tinting the decal alpha by the vertex alpha.
+    /// Expects values in the range [0,1].
+    half _DecalAlphaVertexTint;
+#endif
+
+void aDecal(
+    inout ASurface s)
+{
+#ifdef A_DECAL_ON
+    float2 detailUv = A_TEX_TRANSFORM_UV(s, _DecalTex);
+    half4 decal = _DecalColor * tex2D(_DecalTex, detailUv);
+    half weight = s.mask * _DecalWeight * decal.a * aLerpOneTo(s.vertexColor.a, _DecalAlphaVertexTint);
+    
+    s.baseColor = lerp(s.baseColor, decal.rgb, weight);
+    s.metallic *= 1.0h - weight;
+    s.specularity = lerp(s.specularity, _DecalSpecularity, weight);
+#endif 
+} 
+
+#endif // ALLOY_SHADERS_FEATURE_DECAL_CGINC