18 lines
649 B
JavaScript
18 lines
649 B
JavaScript
import { tslFn } from '../shadernode/ShaderNode.js';
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export const getDistanceAttenuation = tslFn( ( inputs ) => {
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const { lightDistance, cutoffDistance, decayExponent } = inputs;
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// based upon Frostbite 3 Moving to Physically-based Rendering
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// page 32, equation 26: E[window1]
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// https://seblagarde.files.wordpress.com/2015/07/course_notes_moving_frostbite_to_pbr_v32.pdf
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const distanceFalloff = lightDistance.pow( decayExponent ).max( 0.01 ).reciprocal();
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return cutoffDistance.greaterThan( 0 ).cond(
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distanceFalloff.mul( lightDistance.div( cutoffDistance ).pow4().oneMinus().clamp().pow2() ),
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distanceFalloff
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);
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} ); // validated
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