gpu-curtains/dist/esm/core/shaders/chunks/fragment/body/get-iridescence.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.

import { getTextureSample } from "./get-texture-sample.mjs";
//#region src/core/shaders/chunks/fragment/body/get-iridescence.ts
/**
* Set the `iridescence` (`f32`), `iridescenceThickness` (`f32`), `iridescenceF0` (`vec3f`) and `iridescenceFresnel` (`vec3f`) values.
*
* @param parameters - Parameters used to create the shader chunk.
* @param parameters.extensionsUsed - {@link PBRFragmentShaderInputParams.extensionsUsed | extensionsUsed} to check if iridescence is enabled.
* @param parameters.iridescenceTexture - {@link ShaderTextureDescriptor | Iridescence texture descriptor} (using the `R` channel for intensity and `G` channel for thickness) to use if any.
* @param parameters.iridescenceFactorTexture - {@link ShaderTextureDescriptor | Iridescence factor texture descriptor} (using the `R` channel) to use if any.
* @param parameters.iridescenceThicknessTexture - {@link ShaderTextureDescriptor | Iridescence thickness texture descriptor} (using the `G` channel) to use if any.
*/
const getIridescence = ({ extensionsUsed = [], iridescenceTexture = null, iridescenceFactorTexture = null, iridescenceThicknessTexture = null } = {}) => {
	let iridescence = `
  var iridescenceThickness: f32 = 0.0;
  var iridescenceF0: vec3f = vec3(0.0);
  var iridescenceFresnelDielectric: vec3f = vec3(0.0);
  var iridescenceFresnelMetallic: vec3f = vec3(0.0);
  var iridescenceFresnel: vec3f = vec3(0.0);`;
	if (!extensionsUsed.includes("KHR_materials_iridescence")) return iridescence;
	if (iridescenceTexture) {
		iridescence += getTextureSample(iridescenceTexture, "iridescence");
		iridescence += `
  iridescence = iridescence * iridescenceSample.r;
  iridescenceThickness = (iridescenceThicknessRange.y - iridescenceThicknessRange.x) * iridescenceSample.g + iridescenceThicknessRange.x;`;
	} else {
		if (iridescenceFactorTexture) {
			iridescence += getTextureSample(iridescenceFactorTexture, "iridescenceFactor");
			iridescence += `
  iridescence = iridescence * iridescenceFactorSample.r;`;
		}
		if (iridescenceThicknessTexture) {
			iridescence += getTextureSample(iridescenceThicknessTexture, "iridescenceThickness");
			iridescence += `
  iridescenceThickness = (iridescenceThicknessRange.y - iridescenceThicknessRange.x) * iridescenceThicknessSample.g + iridescenceThicknessRange.x;`;
		} else iridescence += `
  iridescenceThickness = iridescenceThicknessRange.y;
    `;
	}
	iridescence += `
  let dotNVi: f32 = saturate( dot( normal, viewDirection ) );

  if ( iridescenceThickness == 0.0 ) {
    iridescence = 0.0;
  } else {
    iridescence = saturate( iridescence );
  }

  if ( iridescence > 0.0 ) {
    iridescenceFresnelDielectric = evalIridescence( 1.0, iridescenceIOR, dotNVi, iridescenceThickness, specularColor );
		iridescenceFresnelMetallic = evalIridescence( 1.0, iridescenceIOR, dotNVi, iridescenceThickness, diffuseColor );
    iridescenceFresnel = mix( iridescenceFresnelDielectric, iridescenceFresnelMetallic, metallic );

    // Iridescence F0 approximation
    iridescenceF0 = Schlick_to_F0( iridescenceFresnel, 1.0, dotNVi );
  }`;
	return iridescence;
};
//#endregion
export { getIridescence };