@openhps/core/dist/esm/three/nodes/functions/BSDF/BRDF_GGX.js

Open Hybrid Positioning System - Core component

import F_Schlick from './F_Schlick.js';
import V_GGX_SmithCorrelated from './V_GGX_SmithCorrelated.js';
import V_GGX_SmithCorrelated_Anisotropic from './V_GGX_SmithCorrelated_Anisotropic.js';
import D_GGX from './D_GGX.js';
import D_GGX_Anisotropic from './D_GGX_Anisotropic.js';
import { transformedNormalView } from '../../accessors/Normal.js';
import { positionViewDirection } from '../../accessors/Position.js';
import { iridescence, alphaT, anisotropyT, anisotropyB } from '../../core/PropertyNode.js';
import { Fn, defined } from '../../tsl/TSLBase.js';

// GGX Distribution, Schlick Fresnel, GGX_SmithCorrelated Visibility
const BRDF_GGX = /*@__PURE__*/Fn(inputs => {
  const {
    lightDirection,
    f0,
    f90,
    roughness,
    f,
    USE_IRIDESCENCE,
    USE_ANISOTROPY
  } = inputs;
  const normalView = inputs.normalView || transformedNormalView;
  const alpha = roughness.pow2(); // UE4's roughness

  const halfDir = lightDirection.add(positionViewDirection).normalize();
  const dotNL = normalView.dot(lightDirection).clamp();
  const dotNV = normalView.dot(positionViewDirection).clamp(); // @ TODO: Move to core dotNV
  const dotNH = normalView.dot(halfDir).clamp();
  const dotVH = positionViewDirection.dot(halfDir).clamp();
  let F = F_Schlick({
    f0,
    f90,
    dotVH
  });
  let V, D;
  if (defined(USE_IRIDESCENCE)) {
    F = iridescence.mix(F, f);
  }
  if (defined(USE_ANISOTROPY)) {
    const dotTL = anisotropyT.dot(lightDirection);
    const dotTV = anisotropyT.dot(positionViewDirection);
    const dotTH = anisotropyT.dot(halfDir);
    const dotBL = anisotropyB.dot(lightDirection);
    const dotBV = anisotropyB.dot(positionViewDirection);
    const dotBH = anisotropyB.dot(halfDir);
    V = V_GGX_SmithCorrelated_Anisotropic({
      alphaT,
      alphaB: alpha,
      dotTV,
      dotBV,
      dotTL,
      dotBL,
      dotNV,
      dotNL
    });
    D = D_GGX_Anisotropic({
      alphaT,
      alphaB: alpha,
      dotNH,
      dotTH,
      dotBH
    });
  } else {
    V = V_GGX_SmithCorrelated({
      alpha,
      dotNL,
      dotNV
    });
    D = D_GGX({
      alpha,
      dotNH
    });
  }
  return F.mul(V).mul(D);
}); // validated

export default BRDF_GGX;