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74 行
2.8 KiB
74 行
2.8 KiB
#ifndef UNITY_COMMON_MATERIAL_INCLUDED
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#define UNITY_COMMON_MATERIAL_INCLUDED
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//-----------------------------------------------------------------------------
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// Helper function for anisotropy
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//-----------------------------------------------------------------------------
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// Ref: http://blog.selfshadow.com/publications/s2012-shading-course/burley/s2012_pbs_disney_brdf_notes_v3.pdf (in addenda)
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// Convert anisotropic ratio (0->no isotropic; 1->full anisotropy in tangent direction) to roughness
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void ConvertAnisotropyToRoughness(float roughness, float anisotropy, out float roughnessT, out float roughnessB)
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{
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// (0 <= anisotropy <= 1), therefore (0 <= anisoAspect <= 1)
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// The 0.9 factor limits the aspect ratio to 10:1.
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float anisoAspect = sqrt(1.0 - 0.9 * anisotropy);
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roughnessT = roughness / anisoAspect; // Distort along tangent (rougher)
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roughnessB = roughness * anisoAspect; // Straighten along bitangent (smoother)
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}
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// Ref: Donald Revie - Implementing Fur Using Deferred Shading (GPU Pro 2)
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// The grain direction (e.g. hair or brush direction) is assumed to be orthogonal to the normal.
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// The returned normal is NOT normalized.
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float3 ComputeGrainNormal(float3 grainDir, float3 V)
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{
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float3 B = cross(-V, grainDir);
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return cross(B, grainDir);
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}
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// Fake anisotropic by distorting the normal.
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// The grain direction (e.g. hair or brush direction) is assumed to be orthogonal to N.
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// Anisotropic ratio (0->no isotropic; 1->full anisotropy in tangent direction)
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float3 GetAnisotropicModifiedNormal(float3 grainDir, float3 N, float3 V, float anisotropy)
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{
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float3 grainNormal = ComputeGrainNormal(grainDir, V);
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// TODO: test whether normalizing 'grainNormal' is worth it.
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return normalize(lerp(N, grainNormal, anisotropy));
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}
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//-----------------------------------------------------------------------------
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// Helper function for perceptual roughness
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//-----------------------------------------------------------------------------
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float PerceptualRoughnessToRoughness(float perceptualRoughness)
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{
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return perceptualRoughness * perceptualRoughness;
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}
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float RoughnessToPerceptualRoughness(float roughness)
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{
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return sqrt(roughness);
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}
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float PerceptualSmoothnessToRoughness(float perceptualSmoothness)
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{
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return (1 - perceptualSmoothness) * (1 - perceptualSmoothness);
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}
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float PerceptualSmoothnessToPerceptualRoughness(float perceptualSmoothness)
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{
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return (1 - perceptualSmoothness);
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}
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// ----------------------------------------------------------------------------
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// Parallax mapping
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// ----------------------------------------------------------------------------
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float2 ParallaxOffset(float3 viewDirTS, float height)
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{
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// Parallax mapping with offset limiting to reduce weird artifcat (i.e do not divide by z), also save performance
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return viewDirTS.xy * height;
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}
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#endif // UNITY_COMMON_MATERIAL_INCLUDED
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