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34 lines
1.1 KiB
34 lines
1.1 KiB
2 years ago
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import F_Schlick from './F_Schlick.js';
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import V_GGX_SmithCorrelated from './V_GGX_SmithCorrelated.js';
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import D_GGX from './D_GGX.js';
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import {
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ShaderNode, dotNV, add, mul, clamp, dot, pow2, normalize,
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transformedNormalView, positionViewDirection
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} from '../../shadernode/ShaderNodeBaseElements.js';
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// GGX Distribution, Schlick Fresnel, GGX_SmithCorrelated Visibility
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const BRDF_GGX = new ShaderNode( ( inputs ) => {
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const { lightDirection, f0, f90, roughness } = inputs;
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const alpha = pow2( roughness ); // UE4's roughness
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const halfDir = normalize( add( lightDirection, positionViewDirection ) );
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const dotNL = clamp( dot( transformedNormalView, lightDirection ) );
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//const dotNV = clamp( dot( transformedNormalView, positionViewDirection ) );
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const dotNH = clamp( dot( transformedNormalView, halfDir ) );
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const dotVH = clamp( dot( positionViewDirection, halfDir ) );
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const F = F_Schlick.call( { f0, f90, dotVH } );
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const V = V_GGX_SmithCorrelated.call( { alpha, dotNL, dotNV } );
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const D = D_GGX.call( { alpha, dotNH } );
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return mul( F, mul( V, D ) );
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} ); // validated
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export default BRDF_GGX;
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