87bdf96449
This commit renames all shader snippet files to conform to the newly introduced naming convention outlined in README.md. The new naming convention uses a `prefix_name.suffix` format to clearly indicate the purpose and target shader stage of each snippet. This improves the overall organization and readability of the shader code, making it easier to understand how each snippet contributes to the shader generation process. No functional changes were made to the shader code itself or source code. This is purely a refactoring for clarity and maintainability.
42 lines
1.8 KiB
GLSL
42 lines
1.8 KiB
GLSL
/**
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* Evalutes lit materials with the subsurface shading model. This model is a
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* combination of a BRDF (the same used in surface_shading_model_standard.fs, refer to that
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* file for more information) and of an approximated BTDF to simulate subsurface
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* scattering. The BTDF itself is not physically based and does not represent a
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* correct interpretation of transmission events.
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*/
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vec3 surfaceShading(const PixelParams pixel, const Light light, float occlusion) {
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vec3 h = normalize(shading_view + light.l);
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float NoL = light.NoL;
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float NoH = saturate(dot(shading_normal, h));
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float LoH = saturate(dot(light.l, h));
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vec3 Fr = vec3(0.0);
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if (NoL > 0.0) {
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// specular BRDF
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float D = distribution(pixel.roughness, NoH, h);
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float V = visibility(pixel.roughness, shading_NoV, NoL);
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vec3 F = fresnel(pixel.f0, LoH);
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Fr = (D * V) * F * pixel.energyCompensation;
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}
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// diffuse BRDF
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vec3 Fd = pixel.diffuseColor * diffuse(pixel.roughness, shading_NoV, NoL, LoH);
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// NoL does not apply to transmitted light
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vec3 color = (Fd + Fr) * (NoL * occlusion);
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// subsurface scattering
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// Use a spherical gaussian approximation of pow() for forwardScattering
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// We could include distortion by adding shading_normal * distortion to light.l
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float scatterVoH = saturate(dot(shading_view, -light.l));
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float forwardScatter = exp2(scatterVoH * pixel.subsurfacePower - pixel.subsurfacePower);
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float backScatter = saturate(NoL * pixel.thickness + (1.0 - pixel.thickness)) * 0.5;
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float subsurface = mix(backScatter, 1.0, forwardScatter) * (1.0 - pixel.thickness);
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color += pixel.subsurfaceColor * (subsurface * Fd_Lambert());
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// TODO: apply occlusion to the transmitted light
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return (color * light.colorIntensity.rgb) * (light.colorIntensity.w * light.attenuation);
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}
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