gpu-curtains/dist/esm/core/shaders/chunks/fragment/head/RE-indirect-specular.mjs

gpu-curtains is a 3D WebGPU rendering engine. It can be used as a standalone 3D engine, but also includes extra classes focused on mapping 3d objects to DOM elements; It allows users to synchronize values such as position, sizing, or scale between them.

//#region src/core/shaders/chunks/fragment/head/RE-indirect-specular.ts
/**
* WGSL functions to calculate the indirect specular and diffuse contributions of lights using multi-scattering.
*/
const REIndirectSpecular = `
// Indirect Specular RenderEquations
fn RE_IndirectSpecular(
  radiance: vec3f,
  irradiance: vec3f,
  diffuseContribution: vec3f,
  metallic: f32,
  sheenEnergyComp: f32,
  dielectricScattering: MultiScattering,
  metallicScattering: MultiScattering,
  ptr_reflectedLight: ptr<function, ReflectedLight>
) {
  // Mix based on metalness
	let singleScattering: vec3f = mix(dielectricScattering.singleScattering, metallicScattering.singleScattering, metallic);
	let multiScattering: vec3f = mix(dielectricScattering.multiScattering, metallicScattering.multiScattering, metallic);

	// Diffuse energy conservation uses dielectric path
	let totalScatteringDielectric: vec3f = dielectricScattering.singleScattering + dielectricScattering.multiScattering;

	let diffuse: vec3f = diffuseContribution * (1.0 - totalScatteringDielectric);

  // we remove RECIPROCAL_PI multiplication since the LUT already ensures energy conservation
  // let cosineWeightedIrradiance: vec3f = irradiance * RECIPROCAL_PI;

  var indirectSpecular: vec3f = radiance * singleScattering;
	indirectSpecular += multiScattering * irradiance;

	var indirectDiffuse: vec3f = diffuse * irradiance;

  indirectSpecular *= sheenEnergyComp;
  indirectDiffuse *= sheenEnergyComp;

  (*ptr_reflectedLight).indirectSpecular += indirectSpecular;  
  (*ptr_reflectedLight).indirectDiffuse += indirectDiffuse;
}
`;
//#endregion
export { REIndirectSpecular };