wehub-resource-sync
92 lines
2.3 KiB
HLSL
92 lines
2.3 KiB
HLSL
// Physically Based Rendering
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// Adapted from 2017-2018 Michał Siejak
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// Physically Based shading model: Lambetrtian diffuse BRDF + Cook-Torrance microfacet specular BRDF + IBL for ambient.
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// This implementation is based on "Real Shading in Unreal Engine 4" SIGGRAPH 2013 course notes by Epic Games.
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// See: http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf
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#ifndef __pbr
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#define __pbr
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#ifndef PI
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#define PI 3.141592
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#endif
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#ifndef Epsilon
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#define Epsilon 0.00001
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#endif
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struct PbrVertex
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{
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float3 Position;
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float3 Normal;
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float3 Tangent;
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float3 Bitangent;
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float2 TexCoord;
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float2 TexCoord2;
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float Selected;
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float3 ColorRGB;
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};
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// Constant normal incidence Fresnel factor for all dielectrics.
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#define Fdielectric 0.04
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// GGX/Towbridge-Reitz normal distribution function.
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// Uses Disney's reparametrization of alpha = roughness^2.
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float ndfGGX(float cosLh, float roughness)
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{
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float alpha = roughness * roughness;
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float alphaSq = alpha * alpha;
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float denom = (cosLh * cosLh) * (alphaSq - 1.0) + 1.0;
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return alphaSq / (PI * denom * denom);
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}
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// Single term for separable Schlick-GGX below.
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float gaSchlickG1(float cosTheta, float k)
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{
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return cosTheta / (cosTheta * (1.0 - k) + k);
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}
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// Schlick-GGX approximation of geometric attenuation function using Smith's method.
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float gaSchlickGGX(float cosLi, float cosLo, float roughness)
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{
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float r = roughness + 1.0;
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float k = (r * r) / 8.0; // Epic suggests using this roughness remapping for analytic lights.
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return gaSchlickG1(cosLi, k) * gaSchlickG1(cosLo, k);
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}
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// Shlick's approximation of the Fresnel factor.
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float3 fresnelSchlick(float3 F0, float cosTheta)
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{
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return F0 + (1.0 - F0) * pow(1.0 - cosTheta, 5.0);
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}
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// Returns number of mipmap levels for specular IBL environment map.
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uint querySpecularTextureLevels(Texture2D specularTexture)
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{
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uint width, height, levels;
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specularTexture.GetDimensions(0, width, height, levels);
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return levels;
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}
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#ifndef __frag_static
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struct FragmentMaterial
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{
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float Roughness;
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float Metalness;
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float Occlusion;
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float cosLo;
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float3 worldPosition;
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float4 albedo;
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float2 uv;
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float3 N;
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float fog;
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float3 Lo;
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};
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static FragmentMaterial frag;
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#define __frag_static
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#endif
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#endif |