@babylonjs/viewer/dist/chunks/gltf-ext-dielectric-BKGcH-t4.esm.js

The Babylon Viewer aims to simplify a specific but common Babylon.js use case: loading, viewing, and interacting with a 3D model.

const ext = {
  id: "KHR_materials_dielectric",
  async applyMaterial(mat, ctx) {
    const exts = mat._rawMatDef?.extensions;
    if (!exts) {
      return null;
    }
    const eIor = exts.KHR_materials_ior;
    const eSp = exts.KHR_materials_specular;
    const eVol = exts.KHR_materials_volume;
    const eTx = exts.KHR_materials_transmission;
    const eDisp = exts.KHR_materials_dispersion;
    if (!eIor && !eSp && !eVol && !eTx && !eDisp) {
      return null;
    }
    const [specTex, specColTex, thickTex, transTex] = await Promise.all([
      ctx._texture(eSp?.specularTexture, false),
      // specularColorTexture is sRGB-encoded, but the reflectance shader applies its
      // own pow(2.2) (matching BJS toLinearSpace on a gammaSpace texture). Load it as
      // a LINEAR-format texture so the GPU does NOT also sRGB-decode on sample — else
      // the dielectric tint is gamma-decoded twice (too dark/saturated), as seen on
      // AnimationPointerUVs col4 specularColorTexture spheres.
      ctx._texture(eSp?.specularColorTexture, false),
      ctx._texture(eVol?.thicknessTexture, false),
      ctx._texture(eTx?.transmissionTexture, false)
    ]);
    const out = {};
    const subsurface = {};
    if (eIor) {
      const ior = typeof eIor.ior === "number" ? eIor.ior : 1.5;
      if (ior !== 1.5) {
        out.metallicF0Factor = ((ior - 1) / (ior + 1)) ** 2 / 0.04;
        out.specularWeight = 1;
        out._hasReflExt = true;
      }
      subsurface.refraction = { indexOfRefraction: ior };
    }
    if (eSp) {
      if (typeof eSp.specularFactor === "number") {
        if (Math.abs(eSp.specularFactor - 1) > 1e-6) {
          out.metallicF0Factor = eSp.specularFactor;
          out.specularWeight = eSp.specularFactor;
          out._hasReflExt = true;
        } else {
          delete out.metallicF0Factor;
          delete out.specularWeight;
        }
      }
      if (Array.isArray(eSp.specularColorFactor) && eSp.specularColorFactor.length === 3) {
        if (eSp.specularColorFactor[0] !== 1 || eSp.specularColorFactor[1] !== 1 || eSp.specularColorFactor[2] !== 1) {
          out.metallicReflectanceColor = [eSp.specularColorFactor[0], eSp.specularColorFactor[1], eSp.specularColorFactor[2]];
          out._hasReflExt = true;
        }
      }
      if (specTex) {
        out.metallicReflectanceTexture = specTex;
        out.useOnlyMetallicFromMetallicReflectanceTexture = true;
      }
      if (specColTex) {
        out.reflectanceTexture = specColTex;
      }
    }
    if (eVol) {
      const thicknessFactor = typeof eVol.thicknessFactor === "number" ? eVol.thicknessFactor : 0;
      if (thicknessFactor > 0 || thickTex) {
        subsurface.thickness = {
          min: 0,
          max: thicknessFactor || 1,
          useGlTFChannel: true,
          ...thickTex ? { texture: thickTex } : void 0
        };
      }
      const color = Array.isArray(eVol.attenuationColor) && eVol.attenuationColor.length === 3 ? eVol.attenuationColor : void 0;
      const atDistance = typeof eVol.attenuationDistance === "number" ? eVol.attenuationDistance : void 0;
      if (color || atDistance !== void 0) {
        subsurface.tint = {
          ...color ? { color } : void 0,
          ...atDistance !== void 0 ? { atDistance } : void 0
        };
      } else if (subsurface.thickness) {
        subsurface.tint = { color: [1, 1, 1], atDistance: 1 };
      }
    }
    if (eTx) {
      const intensity = typeof eTx.transmissionFactor === "number" ? eTx.transmissionFactor : 0;
      if (intensity > 0 || transTex) {
        out.transmissive = true;
        const refraction = {
          ...subsurface.refraction ?? {},
          intensity,
          useThicknessAsDepth: !!subsurface.thickness,
          ...transTex ? { texture: transTex } : void 0
        };
        subsurface.refraction = refraction;
      }
    }
    if (eDisp && typeof eDisp.dispersion === "number" && eDisp.dispersion > 0 && subsurface.refraction && subsurface.thickness) {
      subsurface.refraction = { ...subsurface.refraction, dispersion: 20 / eDisp.dispersion };
    }
    if (Object.keys(subsurface).length > 0) {
      out.subsurface = subsurface;
    }
    return Object.keys(out).length > 0 ? out : null;
  }
};

export { ext as default };
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