/**
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* Compute parameters for physically based rendering using the
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* metallic/roughness workflow. All inputs are linear; sRGB texture values must
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* be decoded beforehand
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*
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* @name czm_pbrMetallicRoughnessMaterial
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* @glslFunction
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*
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* @param {vec3} baseColor For dielectrics, this is the base color. For metals, this is the f0 value (reflectance at normal incidence)
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* @param {float} metallic 0.0 indicates dielectric. 1.0 indicates metal. Values in between are allowed (e.g. to model rust or dirt);
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* @param {float} roughness A value between 0.0 and 1.0
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* @return {czm_pbrParameters} parameters to pass into {@link czm_pbrLighting}
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*/
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czm_pbrParameters czm_pbrMetallicRoughnessMaterial(
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vec3 baseColor,
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float metallic,
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float roughness
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)
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{
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czm_pbrParameters results;
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// roughness is authored as perceptual roughness
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// square it to get material roughness
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roughness = clamp(roughness, 0.0, 1.0);
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results.roughness = roughness * roughness;
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// dielectrics us f0 = 0.04, metals use albedo as f0
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metallic = clamp(metallic, 0.0, 1.0);
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const vec3 REFLECTANCE_DIELECTRIC = vec3(0.04);
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vec3 f0 = mix(REFLECTANCE_DIELECTRIC, baseColor, metallic);
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results.f0 = f0;
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// diffuse only applies to dielectrics.
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results.diffuseColor = baseColor * (1.0 - f0) * (1.0 - metallic);
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return results;
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}
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