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18 lines
629 B
18 lines
629 B
import { ShaderNode, add, sub, mul, exp2 } from '../../shadernode/ShaderNodeBaseElements.js';
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const F_Schlick = new ShaderNode( ( inputs ) => {
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const { f0, f90, dotVH } = inputs;
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// Original approximation by Christophe Schlick '94
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// float fresnel = pow( 1.0 - dotVH, 5.0 );
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// Optimized variant (presented by Epic at SIGGRAPH '13)
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// https://cdn2.unrealengine.com/Resources/files/2013SiggraphPresentationsNotes-26915738.pdf
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const fresnel = exp2( mul( sub( mul( - 5.55473, dotVH ), 6.98316 ), dotVH ) );
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return add( mul( f0, sub( 1.0, fresnel ) ), mul( f90, fresnel ) );
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} ); // validated
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export default F_Schlick;
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