import { Fn } from '../../tsl/TSLBase.js';
// Microfacet Models for Refraction through Rough Surfaces - equation (33)
// http://graphicrants.blogspot.com/2013/08/specular-brdf-reference.html
// alpha is "roughness squared" in Disney’s reparameterization
const D_GGX = /*@__PURE__*/ Fn( ( { alpha, dotNH } ) => {
const a2 = alpha.pow2();
const denom = dotNH.pow2().mul( a2.oneMinus() ).oneMinus(); // avoid alpha = 0 with dotNH = 1
return a2.div( denom.pow2() ).mul( 1 / Math.PI );
} ).setLayout( {
name: 'D_GGX',
type: 'float',
inputs: [
{ name: 'alpha', type: 'float' },
{ name: 'dotNH', type: 'float' }
]
} ); // validated
export default D_GGX;