31 lines
861 B
JavaScript
31 lines
861 B
JavaScript
import { tslFn, vec2, vec4 } from '../../shadernode/ShaderNode.js';
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// Analytical approximation of the DFG LUT, one half of the
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// split-sum approximation used in indirect specular lighting.
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// via 'environmentBRDF' from "Physically Based Shading on Mobile"
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// https://www.unrealengine.com/blog/physically-based-shading-on-mobile
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const DFGApprox = tslFn( ( { roughness, dotNV } ) => {
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const c0 = vec4( - 1, - 0.0275, - 0.572, 0.022 );
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const c1 = vec4( 1, 0.0425, 1.04, - 0.04 );
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const r = roughness.mul( c0 ).add( c1 );
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const a004 = r.x.mul( r.x ).min( dotNV.mul( - 9.28 ).exp2() ).mul( r.x ).add( r.y );
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const fab = vec2( - 1.04, 1.04 ).mul( a004 ).add( r.zw );
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return fab;
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} ).setLayout( {
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name: 'DFGApprox',
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type: 'vec2',
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inputs: [
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{ name: 'roughness', type: 'float' },
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{ name: 'dotNV', type: 'vec3' }
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]
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} );
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export default DFGApprox;
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