text: import {
    AnimationClip,
    Bone,
    Box3,
    BufferAttribute,
    BufferGeometry,
    CanvasTexture,
    ClampToEdgeWrapping,
    Color,
    DirectionalLight,
    DoubleSide,
    FileLoader,
    FrontSide,
    Group,
    ImageBitmapLoader,
    InterleavedBuffer,
    InterleavedBufferAttribute,
    Interpolant,
    InterpolateDiscrete,
    InterpolateLinear,
    Line,
    LineBasicMaterial,
    LineLoop,
    LineSegments,
    LinearFilter,
    LinearMipmapLinearFilter,
    LinearMipmapNearestFilter,
    Loader,
    LoaderUtils,
    Material,
    MathUtils,
    Matrix4,
    Mesh,
    MeshBasicMaterial,
    MeshPhysicalMaterial,
    MeshStandardMaterial,
    MirroredRepeatWrapping,
    NearestFilter,
    NearestMipmapLinearFilter,
    NearestMipmapNearestFilter,
    NumberKeyframeTrack,
    Object3D,
    OrthographicCamera,
    PerspectiveCamera,
    PointLight,
    Points,
    PointsMaterial,
    PropertyBinding,
    QuaternionKeyframeTrack,
    RGBFormat,
    RepeatWrapping,
    Skeleton,
    SkinnedMesh,
    Sphere,
    SpotLight,
    TangentSpaceNormalMap,
    TextureLoader,
    TriangleFanDrawMode,
    TriangleStripDrawMode,
    Vector2,
    Vector3,
    VectorKeyframeTrack,
    sRGBEncoding,
  } from "../three.module.js";
  
  var GLTFLoader = (function () {
    function GLTFLoader(manager) {
      Loader.call(this, manager);
  
      this.dracoLoader = null;
      this.ddsLoader = null;
      this.ktx2Loader = null;
      this.meshoptDecoder = null;
  
      this.pluginCallbacks = [];
  
      this.register(function (parser) {
        return new GLTFMaterialsClearcoatExtension(parser);
      });
  
      this.register(function (parser) {
        return new GLTFTextureBasisUExtension(parser);
      });
  
      this.register(function (parser) {
        return new GLTFTextureWebPExtension(parser);
      });
  
      this.register(function (parser) {
        return new GLTFMaterialsTransmissionExtension(parser);
      });
  
      this.register(function (parser) {
        return new GLTFLightsExtension(parser);
      });
  
      this.register(function (parser) {
        return new GLTFMeshoptCompression(parser);
      });
    }
  
    GLTFLoader.prototype = Object.assign(Object.create(Loader.prototype), {
      constructor: GLTFLoader,
  
      load: function (url, onLoad, onProgress, onError) {
        var scope = this;
  
        var resourcePath;
  
        if (this.resourcePath !== "") {
          resourcePath = this.resourcePath;
        } else if (this.path !== "") {
          resourcePath = this.path;
        } else {
          resourcePath = LoaderUtils.extractUrlBase(url);
        }
  
        // Tells the LoadingManager to track an extra item, which resolves after
        // the model is fully loaded. This means the count of items loaded will
        // be incorrect, but ensures manager.onLoad() does not fire early.
        this.manager.itemStart(url);
  
        var _onError = function (e) {
          if (onError) {
            onError(e);
          } else {
            console.error(e);
          }
  
          scope.manager.itemError(url);
          scope.manager.itemEnd(url);
        };
  
        var loader = new FileLoader(this.manager);
  
        loader.setPath(this.path);
        loader.setResponseType("arraybuffer");
        loader.setRequestHeader(this.requestHeader);
        loader.setWithCredentials(this.withCredentials);
  
        loader.load(
          url,
          function (data) {
            try {
              scope.parse(
                data,
                resourcePath,
                function (gltf) {
                  onLoad(gltf);
  
                  scope.manager.itemEnd(url);
                },
                _onError
              );
            } catch (e) {
              _onError(e);
            }
          },
          onProgress,
          _onError
        );
      },
  
      setDRACOLoader: function (dracoLoader) {
        this.dracoLoader = dracoLoader;
        return this;
      },
  
      setDDSLoader: function (ddsLoader) {
        this.ddsLoader = ddsLoader;
        return this;
      },
  
      setKTX2Loader: function (ktx2Loader) {
        this.ktx2Loader = ktx2Loader;
        return this;
      },
  
      setMeshoptDecoder: function (meshoptDecoder) {
        this.meshoptDecoder = meshoptDecoder;
        return this;
      },
  
      register: function (callback) {
        if (this.pluginCallbacks.indexOf(callback) === -1) {
          this.pluginCallbacks.push(callback);
        }
  
        return this;
      },
  
      unregister: function (callback) {
        if (this.pluginCallbacks.indexOf(callback) !== -1) {
          this.pluginCallbacks.splice(this.pluginCallbacks.indexOf(callback), 1);
        }
  
        return this;
      },
  
      parse: function (data, path, onLoad, onError) {
        var content;
        var extensions = {};
        var plugins = {};
  
        if (typeof data === "string") {
          content = data;
        } else {
          var magic = LoaderUtils.decodeText(new Uint8Array(data, 0, 4));
  
          if (magic === BINARY_EXTENSION_HEADER_MAGIC) {
            try {
              extensions[EXTENSIONS.KHR_BINARY_GLTF] = new GLTFBinaryExtension(
                data
              );
            } catch (error) {
              if (onError) onError(error);
              return;
            }
  
            content = extensions[EXTENSIONS.KHR_BINARY_GLTF].content;
          } else {
            content = LoaderUtils.decodeText(new Uint8Array(data));
          }
        }
  
        var json = JSON.parse(content);
  
        if (json.asset === undefined || json.asset.version[0] < 2) {
          if (onError)
            onError(
              new Error(
                "THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported."
              )
            );
          return;
        }
  
        var parser = new GLTFParser(json, {
          path: path || this.resourcePath || "",
          crossOrigin: this.crossOrigin,
          manager: this.manager,
          ktx2Loader: this.ktx2Loader,
          meshoptDecoder: this.meshoptDecoder,
        });
  
        parser.fileLoader.setRequestHeader(this.requestHeader);
  
        for (var i = 0; i < this.pluginCallbacks.length; i++) {
          var plugin = this.pluginCallbacks[i](parser);
          plugins[plugin.name] = plugin;
  
          // Workaround to avoid determining as unknown extension
          // in addUnknownExtensionsToUserData().
          // Remove this workaround if we move all the existing
          // extension handlers to plugin system
          extensions[plugin.name] = true;
        }
  
        if (json.extensionsUsed) {
          for (var i = 0; i < json.extensionsUsed.length; ++i) {
            var extensionName = json.extensionsUsed[i];
            var extensionsRequired = json.extensionsRequired || [];
  
            switch (extensionName) {
              case EXTENSIONS.KHR_MATERIALS_UNLIT:
                extensions[extensionName] = new GLTFMaterialsUnlitExtension();
                break;
  
              case EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
                extensions[
                  extensionName
                ] = new GLTFMaterialsPbrSpecularGlossinessExtension();
                break;
  
              case EXTENSIONS.KHR_DRACO_MESH_COMPRESSION:
                extensions[extensionName] = new GLTFDracoMeshCompressionExtension(
                  json,
                  this.dracoLoader
                );
                break;
  
              case EXTENSIONS.MSFT_TEXTURE_DDS:
                extensions[extensionName] = new GLTFTextureDDSExtension(
                  this.ddsLoader
                );
                break;
  
              case EXTENSIONS.KHR_TEXTURE_TRANSFORM:
                extensions[extensionName] = new GLTFTextureTransformExtension();
                break;
  
              case EXTENSIONS.KHR_MESH_QUANTIZATION:
                extensions[extensionName] = new GLTFMeshQuantizationExtension();
                break;
  
              default:
                if (
                  extensionsRequired.indexOf(extensionName) >= 0 &&
                  plugins[extensionName] === undefined
                ) {
                  console.warn(
                    'THREE.GLTFLoader: Unknown extension "' + extensionName + '".'
                  );
                }
            }
          }
        }
  
        parser.setExtensions(extensions);
        parser.setPlugins(plugins);
        parser.parse(onLoad, onError);
      },
    });
  
    /* GLTFREGISTRY */
  
    function GLTFRegistry() {
      var objects = {};
  
      return {
        get: function (key) {
          return objects[key];
        },
  
        add: function (key, object) {
          objects[key] = object;
        },
  
        remove: function (key) {
          delete objects[key];
        },
  
        removeAll: function () {
          objects = {};
        },
      };
    }
  
    /*********************************/
    /********** EXTENSIONS ***********/
    /*********************************/
  
    var EXTENSIONS = {
      KHR_BINARY_GLTF: "KHR_binary_glTF",
      KHR_DRACO_MESH_COMPRESSION: "KHR_draco_mesh_compression",
      KHR_LIGHTS_PUNCTUAL: "KHR_lights_punctual",
      KHR_MATERIALS_CLEARCOAT: "KHR_materials_clearcoat",
      KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
        "KHR_materials_pbrSpecularGlossiness",
      KHR_MATERIALS_TRANSMISSION: "KHR_materials_transmission",
      KHR_MATERIALS_UNLIT: "KHR_materials_unlit",
      KHR_TEXTURE_BASISU: "KHR_texture_basisu",
      KHR_TEXTURE_TRANSFORM: "KHR_texture_transform",
      KHR_MESH_QUANTIZATION: "KHR_mesh_quantization",
      EXT_TEXTURE_WEBP: "EXT_texture_webp",
      EXT_MESHOPT_COMPRESSION: "EXT_meshopt_compression",
      MSFT_TEXTURE_DDS: "MSFT_texture_dds",
    };
  
    /**
     * DDS Texture Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/MSFT_texture_dds
     *
     */
    function GLTFTextureDDSExtension(ddsLoader) {
      if (!ddsLoader) {
        throw new Error(
          "THREE.GLTFLoader: Attempting to load .dds texture without importing DDSLoader"
        );
      }
  
      this.name = EXTENSIONS.MSFT_TEXTURE_DDS;
      this.ddsLoader = ddsLoader;
    }
  
    /**
     * Punctual Lights Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
     */
    function GLTFLightsExtension(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;
  
      // Object3D instance caches
      this.cache = { refs: {}, uses: {} };
    }
  
    GLTFLightsExtension.prototype._markDefs = function () {
      var parser = this.parser;
      var nodeDefs = this.parser.json.nodes || [];
  
      for (
        var nodeIndex = 0, nodeLength = nodeDefs.length;
        nodeIndex < nodeLength;
        nodeIndex++
      ) {
        var nodeDef = nodeDefs[nodeIndex];
  
        if (
          nodeDef.extensions &&
          nodeDef.extensions[this.name] &&
          nodeDef.extensions[this.name].light !== undefined
        ) {
          parser._addNodeRef(this.cache, nodeDef.extensions[this.name].light);
        }
      }
    };
  
    GLTFLightsExtension.prototype._loadLight = function (lightIndex) {
      var parser = this.parser;
      var cacheKey = "light:" + lightIndex;
      var dependency = parser.cache.get(cacheKey);
  
      if (dependency) return dependency;
  
      var json = parser.json;
      var extensions = (json.extensions && json.extensions[this.name]) || {};
      var lightDefs = extensions.lights || [];
      var lightDef = lightDefs[lightIndex];
      var lightNode;
  
      var color = new Color(0xffffff);
  
      if (lightDef.color !== undefined) color.fromArray(lightDef.color);
  
      var range = lightDef.range !== undefined ? lightDef.range : 0;
  
      switch (lightDef.type) {
        case "directional":
          lightNode = new DirectionalLight(color);
          lightNode.target.position.set(0, 0, -1);
          lightNode.add(lightNode.target);
          break;
  
        case "point":
          lightNode = new PointLight(color);
          lightNode.distance = range;
          break;
  
        case "spot":
          lightNode = new SpotLight(color);
          lightNode.distance = range;
          // Handle spotlight properties.
          lightDef.spot = lightDef.spot || {};
          lightDef.spot.innerConeAngle =
            lightDef.spot.innerConeAngle !== undefined
              ? lightDef.spot.innerConeAngle
              : 0;
          lightDef.spot.outerConeAngle =
            lightDef.spot.outerConeAngle !== undefined
              ? lightDef.spot.outerConeAngle
              : Math.PI / 4.0;
          lightNode.angle = lightDef.spot.outerConeAngle;
          lightNode.penumbra =
            1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
          lightNode.target.position.set(0, 0, -1);
          lightNode.add(lightNode.target);
          break;
  
        default:
          throw new Error(
            'THREE.GLTFLoader: Unexpected light type, "' + lightDef.type + '".'
          );
      }
  
      // Some lights (e.g. spot) default to a position other than the origin. Reset the position
      // here, because node-level parsing will only override position if explicitly specified.
      lightNode.position.set(0, 0, 0);
  
      lightNode.decay = 2;
  
      if (lightDef.intensity !== undefined)
        lightNode.intensity = lightDef.intensity;
  
      lightNode.name = parser.createUniqueName(
        lightDef.name || "light_" + lightIndex
      );
  
      dependency = Promise.resolve(lightNode);
  
      parser.cache.add(cacheKey, dependency);
  
      return dependency;
    };
  
    GLTFLightsExtension.prototype.createNodeAttachment = function (nodeIndex) {
      var self = this;
      var parser = this.parser;
      var json = parser.json;
      var nodeDef = json.nodes[nodeIndex];
      var lightDef = (nodeDef.extensions && nodeDef.extensions[this.name]) || {};
      var lightIndex = lightDef.light;
  
      if (lightIndex === undefined) return null;
  
      return this._loadLight(lightIndex).then(function (light) {
        return parser._getNodeRef(self.cache, lightIndex, light);
      });
    };
  
    /**
     * Unlit Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
     */
    function GLTFMaterialsUnlitExtension() {
      this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;
    }
  
    GLTFMaterialsUnlitExtension.prototype.getMaterialType = function () {
      return MeshBasicMaterial;
    };
  
    GLTFMaterialsUnlitExtension.prototype.extendParams = function (
      materialParams,
      materialDef,
      parser
    ) {
      var pending = [];
  
      materialParams.color = new Color(1.0, 1.0, 1.0);
      materialParams.opacity = 1.0;
  
      var metallicRoughness = materialDef.pbrMetallicRoughness;
  
      if (metallicRoughness) {
        if (Array.isArray(metallicRoughness.baseColorFactor)) {
          var array = metallicRoughness.baseColorFactor;
  
          materialParams.color.fromArray(array);
          materialParams.opacity = array[3];
        }
  
        if (metallicRoughness.baseColorTexture !== undefined) {
          pending.push(
            parser.assignTexture(
              materialParams,
              "map",
              metallicRoughness.baseColorTexture
            )
          );
        }
      }
  
      return Promise.all(pending);
    };
  
    /**
     * Clearcoat Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
     */
    function GLTFMaterialsClearcoatExtension(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;
    }
  
    GLTFMaterialsClearcoatExtension.prototype.getMaterialType = function (
      materialIndex
    ) {
      var parser = this.parser;
      var materialDef = parser.json.materials[materialIndex];
  
      if (!materialDef.extensions || !materialDef.extensions[this.name])
        return null;
  
      return MeshPhysicalMaterial;
    };
  
    GLTFMaterialsClearcoatExtension.prototype.extendMaterialParams = function (
      materialIndex,
      materialParams
    ) {
      var parser = this.parser;
      var materialDef = parser.json.materials[materialIndex];
  
      if (!materialDef.extensions || !materialDef.extensions[this.name]) {
        return Promise.resolve();
      }
  
      var pending = [];
  
      var extension = materialDef.extensions[this.name];
  
      if (extension.clearcoatFactor !== undefined) {
        materialParams.clearcoat = extension.clearcoatFactor;
      }
  
      if (extension.clearcoatTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "clearcoatMap",
            extension.clearcoatTexture
          )
        );
      }
  
      if (extension.clearcoatRoughnessFactor !== undefined) {
        materialParams.clearcoatRoughness = extension.clearcoatRoughnessFactor;
      }
  
      if (extension.clearcoatRoughnessTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "clearcoatRoughnessMap",
            extension.clearcoatRoughnessTexture
          )
        );
      }
  
      if (extension.clearcoatNormalTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "clearcoatNormalMap",
            extension.clearcoatNormalTexture
          )
        );
  
        if (extension.clearcoatNormalTexture.scale !== undefined) {
          var scale = extension.clearcoatNormalTexture.scale;
  
          materialParams.clearcoatNormalScale = new Vector2(scale, scale);
        }
      }
  
      return Promise.all(pending);
    };
  
    /**
     * Transmission Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_transmission
     * Draft: https://github.com/KhronosGroup/glTF/pull/1698
     */
    function GLTFMaterialsTransmissionExtension(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_MATERIALS_TRANSMISSION;
    }
  
    GLTFMaterialsTransmissionExtension.prototype.getMaterialType = function (
      materialIndex
    ) {
      var parser = this.parser;
      var materialDef = parser.json.materials[materialIndex];
  
      if (!materialDef.extensions || !materialDef.extensions[this.name])
        return null;
  
      return MeshPhysicalMaterial;
    };
  
    GLTFMaterialsTransmissionExtension.prototype.extendMaterialParams = function (
      materialIndex,
      materialParams
    ) {
      var parser = this.parser;
      var materialDef = parser.json.materials[materialIndex];
  
      if (!materialDef.extensions || !materialDef.extensions[this.name]) {
        return Promise.resolve();
      }
  
      var pending = [];
  
      var extension = materialDef.extensions[this.name];
  
      if (extension.transmissionFactor !== undefined) {
        materialParams.transmission = extension.transmissionFactor;
      }
  
      if (extension.transmissionTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "transmissionMap",
            extension.transmissionTexture
          )
        );
      }
  
      return Promise.all(pending);
    };
  
    /**
     * BasisU Texture Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu
     */
    function GLTFTextureBasisUExtension(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_TEXTURE_BASISU;
    }
  
    GLTFTextureBasisUExtension.prototype.loadTexture = function (textureIndex) {
      var parser = this.parser;
      var json = parser.json;
  
      var textureDef = json.textures[textureIndex];
  
      if (!textureDef.extensions || !textureDef.extensions[this.name]) {
        return null;
      }
  
      var extension = textureDef.extensions[this.name];
      var source = json.images[extension.source];
      var loader = parser.options.ktx2Loader;
  
      if (!loader) {
        if (
          json.extensionsRequired &&
          json.extensionsRequired.indexOf(this.name) >= 0
        ) {
          throw new Error(
            "THREE.GLTFLoader: setKTX2Loader must be called before loading KTX2 textures"
          );
        } else {
          // Assumes that the extension is optional and that a fallback texture is present
          return null;
        }
      }
  
      return parser.loadTextureImage(textureIndex, source, loader);
    };
  
    /**
     * WebP Texture Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_texture_webp
     */
    function GLTFTextureWebPExtension(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.EXT_TEXTURE_WEBP;
      this.isSupported = null;
    }
  
    GLTFTextureWebPExtension.prototype.loadTexture = function (textureIndex) {
      var name = this.name;
      var parser = this.parser;
      var json = parser.json;
  
      var textureDef = json.textures[textureIndex];
  
      if (!textureDef.extensions || !textureDef.extensions[name]) {
        return null;
      }
  
      var extension = textureDef.extensions[name];
      var source = json.images[extension.source];
      var loader = source.uri
        ? parser.options.manager.getHandler(source.uri)
        : parser.textureLoader;
  
      return this.detectSupport().then(function (isSupported) {
        if (isSupported)
          return parser.loadTextureImage(textureIndex, source, loader);
  
        if (
          json.extensionsRequired &&
          json.extensionsRequired.indexOf(name) >= 0
        ) {
          throw new Error(
            "THREE.GLTFLoader: WebP required by asset but unsupported."
          );
        }
  
        // Fall back to PNG or JPEG.
        return parser.loadTexture(textureIndex);
      });
    };
  
    GLTFTextureWebPExtension.prototype.detectSupport = function () {
      if (!this.isSupported) {
        this.isSupported = new Promise(function (resolve) {
          var image = new Image();
  
          // Lossy test image. Support for lossy images doesn't guarantee support for all
          // WebP images, unfortunately.
          image.src =
            "data:image/webp;base64,UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA";
  
          image.onload = image.onerror = function () {
            resolve(image.height === 1);
          };
        });
      }
  
      return this.isSupported;
    };
  
    /**
     * meshopt BufferView Compression Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_meshopt_compression
     */
    function GLTFMeshoptCompression(parser) {
      this.name = EXTENSIONS.EXT_MESHOPT_COMPRESSION;
      this.parser = parser;
    }
  
    GLTFMeshoptCompression.prototype.loadBufferView = function (index) {
      var json = this.parser.json;
      var bufferView = json.bufferViews[index];
  
      if (bufferView.extensions && bufferView.extensions[this.name]) {
        var extensionDef = bufferView.extensions[this.name];
  
        var buffer = this.parser.getDependency("buffer", extensionDef.buffer);
        var decoder = this.parser.options.meshoptDecoder;
  
        if (!decoder || !decoder.supported) {
          if (
            json.extensionsRequired &&
            json.extensionsRequired.indexOf(this.name) >= 0
          ) {
            throw new Error(
              "THREE.GLTFLoader: setMeshoptDecoder must be called before loading compressed files"
            );
          } else {
            // Assumes that the extension is optional and that fallback buffer data is present
            return null;
          }
        }
  
        return Promise.all([buffer, decoder.ready]).then(function (res) {
          var byteOffset = extensionDef.byteOffset || 0;
          var byteLength = extensionDef.byteLength || 0;
  
          var count = extensionDef.count;
          var stride = extensionDef.byteStride;
  
          var result = new ArrayBuffer(count * stride);
          var source = new Uint8Array(res[0], byteOffset, byteLength);
  
          decoder.decodeGltfBuffer(
            new Uint8Array(result),
            count,
            stride,
            source,
            extensionDef.mode,
            extensionDef.filter
          );
          return result;
        });
      } else {
        return null;
      }
    };
  
    /* BINARY EXTENSION */
    var BINARY_EXTENSION_HEADER_MAGIC = "glTF";
    var BINARY_EXTENSION_HEADER_LENGTH = 12;
    var BINARY_EXTENSION_CHUNK_TYPES = { JSON: 0x4e4f534a, BIN: 0x004e4942 };
  
    function GLTFBinaryExtension(data) {
      this.name = EXTENSIONS.KHR_BINARY_GLTF;
      this.content = null;
      this.body = null;
  
      var headerView = new DataView(data, 0, BINARY_EXTENSION_HEADER_LENGTH);
  
      this.header = {
        magic: LoaderUtils.decodeText(new Uint8Array(data.slice(0, 4))),
        version: headerView.getUint32(4, true),
        length: headerView.getUint32(8, true),
      };
  
      if (this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC) {
        throw new Error("THREE.GLTFLoader: Unsupported glTF-Binary header.");
      } else if (this.header.version < 2.0) {
        throw new Error("THREE.GLTFLoader: Legacy binary file detected.");
      }
  
      var chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH);
      var chunkIndex = 0;
  
      while (chunkIndex < chunkView.byteLength) {
        var chunkLength = chunkView.getUint32(chunkIndex, true);
        chunkIndex += 4;
  
        var chunkType = chunkView.getUint32(chunkIndex, true);
        chunkIndex += 4;
  
        if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {
          var contentArray = new Uint8Array(
            data,
            BINARY_EXTENSION_HEADER_LENGTH + chunkIndex,
            chunkLength
          );
          this.content = LoaderUtils.decodeText(contentArray);
        } else if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN) {
          var byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
          this.body = data.slice(byteOffset, byteOffset + chunkLength);
        }
  
        // Clients must ignore chunks with unknown types.
  
        chunkIndex += chunkLength;
      }
  
      if (this.content === null) {
        throw new Error("THREE.GLTFLoader: JSON content not found.");
      }
    }
  
    /**
     * DRACO Mesh Compression Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
     */
    function GLTFDracoMeshCompressionExtension(json, dracoLoader) {
      if (!dracoLoader) {
        throw new Error("THREE.GLTFLoader: No DRACOLoader instance provided.");
      }
  
      this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
      this.json = json;
      this.dracoLoader = dracoLoader;
      this.dracoLoader.preload();
    }
  
    GLTFDracoMeshCompressionExtension.prototype.decodePrimitive = function (
      primitive,
      parser
    ) {
      var json = this.json;
      var dracoLoader = this.dracoLoader;
      var bufferViewIndex = primitive.extensions[this.name].bufferView;
      var gltfAttributeMap = primitive.extensions[this.name].attributes;
      var threeAttributeMap = {};
      var attributeNormalizedMap = {};
      var attributeTypeMap = {};
  
      for (var attributeName in gltfAttributeMap) {
        var threeAttributeName =
          ATTRIBUTES[attributeName] || attributeName.toLowerCase();
  
        threeAttributeMap[threeAttributeName] = gltfAttributeMap[attributeName];
      }
  
      for (attributeName in primitive.attributes) {
        var threeAttributeName =
          ATTRIBUTES[attributeName] || attributeName.toLowerCase();
  
        if (gltfAttributeMap[attributeName] !== undefined) {
          var accessorDef = json.accessors[primitive.attributes[attributeName]];
          var componentType = WEBGL_COMPONENT_TYPES[accessorDef.componentType];
  
          attributeTypeMap[threeAttributeName] = componentType;
          attributeNormalizedMap[threeAttributeName] =
            accessorDef.normalized === true;
        }
      }
  
      return parser
        .getDependency("bufferView", bufferViewIndex)
        .then(function (bufferView) {
          return new Promise(function (resolve) {
            dracoLoader.decodeDracoFile(
              bufferView,
              function (geometry) {
                for (var attributeName in geometry.attributes) {
                  var attribute = geometry.attributes[attributeName];
                  var normalized = attributeNormalizedMap[attributeName];
  
                  if (normalized !== undefined) attribute.normalized = normalized;
                }
  
                resolve(geometry);
              },
              threeAttributeMap,
              attributeTypeMap
            );
          });
        });
    };
  
    /**
     * Texture Transform Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
     */
    function GLTFTextureTransformExtension() {
      this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;
    }
  
    GLTFTextureTransformExtension.prototype.extendTexture = function (
      texture,
      transform
    ) {
      texture = texture.clone();
  
      if (transform.offset !== undefined) {
        texture.offset.fromArray(transform.offset);
      }
  
      if (transform.rotation !== undefined) {
        texture.rotation = transform.rotation;
      }
  
      if (transform.scale !== undefined) {
        texture.repeat.fromArray(transform.scale);
      }
  
      if (transform.texCoord !== undefined) {
        console.warn(
          'THREE.GLTFLoader: Custom UV sets in "' +
            this.name +
            '" extension not yet supported.'
        );
      }
  
      texture.needsUpdate = true;
  
      return texture;
    };
  
    /**
     * Specular-Glossiness Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness
     */
  
    /**
     * A sub class of StandardMaterial with some of the functionality
     * changed via the `onBeforeCompile` callback
     * @pailhead
     */
  
    function GLTFMeshStandardSGMaterial(params) {
      MeshStandardMaterial.call(this);
  
      this.isGLTFSpecularGlossinessMaterial = true;
  
      //various chunks that need replacing
      var specularMapParsFragmentChunk = [
        "#ifdef USE_SPECULARMAP",
        "	uniform sampler2D specularMap;",
        "#endif",
      ].join("\n");
  
      var glossinessMapParsFragmentChunk = [
        "#ifdef USE_GLOSSINESSMAP",
        "	uniform sampler2D glossinessMap;",
        "#endif",
      ].join("\n");
  
      var specularMapFragmentChunk = [
        "vec3 specularFactor = specular;",
        "#ifdef USE_SPECULARMAP",
        "	vec4 texelSpecular = texture2D( specularMap, vUv );",
        "	texelSpecular = sRGBToLinear( texelSpecular );",
        "	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture",
        "	specularFactor *= texelSpecular.rgb;",
        "#endif",
      ].join("\n");
  
      var glossinessMapFragmentChunk = [
        "float glossinessFactor = glossiness;",
        "#ifdef USE_GLOSSINESSMAP",
        "	vec4 texelGlossiness = texture2D( glossinessMap, vUv );",
        "	// reads channel A, compatible with a glTF Specular-Glossiness (RGBA) texture",
        "	glossinessFactor *= texelGlossiness.a;",
        "#endif",
      ].join("\n");
  
      var lightPhysicalFragmentChunk = [
        "PhysicalMaterial material;",
        "material.diffuseColor = diffuseColor.rgb * ( 1. - max( specularFactor.r, max( specularFactor.g, specularFactor.b ) ) );",
        "vec3 dxy = max( abs( dFdx( geometryNormal ) ), abs( dFdy( geometryNormal ) ) );",
        "float geometryRoughness = max( max( dxy.x, dxy.y ), dxy.z );",
        "material.specularRoughness = max( 1.0 - glossinessFactor, 0.0525 ); // 0.0525 corresponds to the base mip of a 256 cubemap.",
        "material.specularRoughness += geometryRoughness;",
        "material.specularRoughness = min( material.specularRoughness, 1.0 );",
        "material.specularColor = specularFactor;",
      ].join("\n");
  
      var uniforms = {
        specular: { value: new Color().setHex(0xffffff) },
        glossiness: { value: 1 },
        specularMap: { value: null },
        glossinessMap: { value: null },
      };
  
      this._extraUniforms = uniforms;
  
      this.onBeforeCompile = function (shader) {
        for (var uniformName in uniforms) {
          shader.uniforms[uniformName] = uniforms[uniformName];
        }
  
        shader.fragmentShader = shader.fragmentShader
          .replace("uniform float roughness;", "uniform vec3 specular;")
          .replace("uniform float metalness;", "uniform float glossiness;")
          .replace(
            "#include <roughnessmap_pars_fragment>",
            specularMapParsFragmentChunk
          )
          .replace(
            "#include <metalnessmap_pars_fragment>",
            glossinessMapParsFragmentChunk
          )
          .replace("#include <roughnessmap_fragment>", specularMapFragmentChunk)
          .replace("#include <metalnessmap_fragment>", glossinessMapFragmentChunk)
          .replace(
            "#include <lights_physical_fragment>",
            lightPhysicalFragmentChunk
          );
      };
  
      Object.defineProperties(this, {
        specular: {
          get: function () {
            return uniforms.specular.value;
          },
          set: function (v) {
            uniforms.specular.value = v;
          },
        },
  
        specularMap: {
          get: function () {
            return uniforms.specularMap.value;
          },
          set: function (v) {
            uniforms.specularMap.value = v;
  
            if (v) {
              this.defines.USE_SPECULARMAP = ""; // USE_UV is set by the renderer for specular maps
            } else {
              delete this.defines.USE_SPECULARMAP;
            }
          },
        },
  
        glossiness: {
          get: function () {
            return uniforms.glossiness.value;
          },
          set: function (v) {
            uniforms.glossiness.value = v;
          },
        },
  
        glossinessMap: {
          get: function () {
            return uniforms.glossinessMap.value;
          },
          set: function (v) {
            uniforms.glossinessMap.value = v;
  
            if (v) {
              this.defines.USE_GLOSSINESSMAP = "";
              this.defines.USE_UV = "";
            } else {
              delete this.defines.USE_GLOSSINESSMAP;
              delete this.defines.USE_UV;
            }
          },
        },
      });
  
      delete this.metalness;
      delete this.roughness;
      delete this.metalnessMap;
      delete this.roughnessMap;
  
      this.setValues(params);
    }
  
    GLTFMeshStandardSGMaterial.prototype = Object.create(
      MeshStandardMaterial.prototype
    );
    GLTFMeshStandardSGMaterial.prototype.constructor = GLTFMeshStandardSGMaterial;
  
    GLTFMeshStandardSGMaterial.prototype.copy = function (source) {
      MeshStandardMaterial.prototype.copy.call(this, source);
      this.specularMap = source.specularMap;
      this.specular.copy(source.specular);
      this.glossinessMap = source.glossinessMap;
      this.glossiness = source.glossiness;
      delete this.metalness;
      delete this.roughness;
      delete this.metalnessMap;
      delete this.roughnessMap;
      return this;
    };
  
    function GLTFMaterialsPbrSpecularGlossinessExtension() {
      return {
        name: EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS,
  
        specularGlossinessParams: [
          "color",
          "map",
          "lightMap",
          "lightMapIntensity",
          "aoMap",
          "aoMapIntensity",
          "emissive",
          "emissiveIntensity",
          "emissiveMap",
          "bumpMap",
          "bumpScale",
          "normalMap",
          "normalMapType",
          "displacementMap",
          "displacementScale",
          "displacementBias",
          "specularMap",
          "specular",
          "glossinessMap",
          "glossiness",
          "alphaMap",
          "envMap",
          "envMapIntensity",
          "refractionRatio",
        ],
  
        getMaterialType: function () {
          return GLTFMeshStandardSGMaterial;
        },
  
        extendParams: function (materialParams, materialDef, parser) {
          var pbrSpecularGlossiness = materialDef.extensions[this.name];
  
          materialParams.color = new Color(1.0, 1.0, 1.0);
          materialParams.opacity = 1.0;
  
          var pending = [];
  
          if (Array.isArray(pbrSpecularGlossiness.diffuseFactor)) {
            var array = pbrSpecularGlossiness.diffuseFactor;
  
            materialParams.color.fromArray(array);
            materialParams.opacity = array[3];
          }
  
          if (pbrSpecularGlossiness.diffuseTexture !== undefined) {
            pending.push(
              parser.assignTexture(
                materialParams,
                "map",
                pbrSpecularGlossiness.diffuseTexture
              )
            );
          }
  
          materialParams.emissive = new Color(0.0, 0.0, 0.0);
          materialParams.glossiness =
            pbrSpecularGlossiness.glossinessFactor !== undefined
              ? pbrSpecularGlossiness.glossinessFactor
              : 1.0;
          materialParams.specular = new Color(1.0, 1.0, 1.0);
  
          if (Array.isArray(pbrSpecularGlossiness.specularFactor)) {
            materialParams.specular.fromArray(
              pbrSpecularGlossiness.specularFactor
            );
          }
  
          if (pbrSpecularGlossiness.specularGlossinessTexture !== undefined) {
            var specGlossMapDef = pbrSpecularGlossiness.specularGlossinessTexture;
            pending.push(
              parser.assignTexture(
                materialParams,
                "glossinessMap",
                specGlossMapDef
              )
            );
            pending.push(
              parser.assignTexture(materialParams, "specularMap", specGlossMapDef)
            );
          }
  
          return Promise.all(pending);
        },
  
        createMaterial: function (materialParams) {
          var material = new GLTFMeshStandardSGMaterial(materialParams);
          material.fog = true;
  
          material.color = materialParams.color;
  
          material.map =
            materialParams.map === undefined ? null : materialParams.map;
  
          material.lightMap = null;
          material.lightMapIntensity = 1.0;
  
          material.aoMap =
            materialParams.aoMap === undefined ? null : materialParams.aoMap;
          material.aoMapIntensity = 1.0;
  
          material.emissive = materialParams.emissive;
          material.emissiveIntensity = 1.0;
          material.emissiveMap =
            materialParams.emissiveMap === undefined
              ? null
              : materialParams.emissiveMap;
  
          material.bumpMap =
            materialParams.bumpMap === undefined ? null : materialParams.bumpMap;
          material.bumpScale = 1;
  
          material.normalMap =
            materialParams.normalMap === undefined
              ? null
              : materialParams.normalMap;
          material.normalMapType = TangentSpaceNormalMap;
  
          if (materialParams.normalScale)
            material.normalScale = materialParams.normalScale;
  
          material.displacementMap = null;
          material.displacementScale = 1;
          material.displacementBias = 0;
  
          material.specularMap =
            materialParams.specularMap === undefined
              ? null
              : materialParams.specularMap;
          material.specular = materialParams.specular;
  
          material.glossinessMap =
            materialParams.glossinessMap === undefined
              ? null
              : materialParams.glossinessMap;
          material.glossiness = materialParams.glossiness;
  
          material.alphaMap = null;
  
          material.envMap =
            materialParams.envMap === undefined ? null : materialParams.envMap;
          material.envMapIntensity = 1.0;
  
          material.refractionRatio = 0.98;
  
          return material;
        },
      };
    }
  
    /**
     * Mesh Quantization Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
     */
    function GLTFMeshQuantizationExtension() {
      this.name = EXTENSIONS.KHR_MESH_QUANTIZATION;
    }
  
    /*********************************/
    /********** INTERPOLATION ********/
    /*********************************/
  
    // Spline Interpolation
    // Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
    function GLTFCubicSplineInterpolant(
      parameterPositions,
      sampleValues,
      sampleSize,
      resultBuffer
    ) {
      Interpolant.call(
        this,
        parameterPositions,
        sampleValues,
        sampleSize,
        resultBuffer
      );
    }
  
    GLTFCubicSplineInterpolant.prototype = Object.create(Interpolant.prototype);
    GLTFCubicSplineInterpolant.prototype.constructor = GLTFCubicSplineInterpolant;
  
    GLTFCubicSplineInterpolant.prototype.copySampleValue_ = function (index) {
      // Copies a sample value to the result buffer. See description of glTF
      // CUBICSPLINE values layout in interpolate_() function below.
  
      var result = this.resultBuffer,
        values = this.sampleValues,
        valueSize = this.valueSize,
        offset = index * valueSize * 3 + valueSize;
  
      for (var i = 0; i !== valueSize; i++) {
        result[i] = values[offset + i];
      }
  
      return result;
    };
  
    GLTFCubicSplineInterpolant.prototype.beforeStart_ =
      GLTFCubicSplineInterpolant.prototype.copySampleValue_;
  
    GLTFCubicSplineInterpolant.prototype.afterEnd_ =
      GLTFCubicSplineInterpolant.prototype.copySampleValue_;
  
    GLTFCubicSplineInterpolant.prototype.interpolate_ = function (i1, t0, t, t1) {
      var result = this.resultBuffer;
      var values = this.sampleValues;
      var stride = this.valueSize;
  
      var stride2 = stride * 2;
      var stride3 = stride * 3;
  
      var td = t1 - t0;
  
      var p = (t - t0) / td;
      var pp = p * p;
      var ppp = pp * p;
  
      var offset1 = i1 * stride3;
      var offset0 = offset1 - stride3;
  
      var s2 = -2 * ppp + 3 * pp;
      var s3 = ppp - pp;
      var s0 = 1 - s2;
      var s1 = s3 - pp + p;
  
      // Layout of keyframe output values for CUBICSPLINE animations:
      //   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]
      for (var i = 0; i !== stride; i++) {
        var p0 = values[offset0 + i + stride]; // splineVertex_k
        var m0 = values[offset0 + i + stride2] * td; // outTangent_k * (t_k+1 - t_k)
        var p1 = values[offset1 + i + stride]; // splineVertex_k+1
        var m1 = values[offset1 + i] * td; // inTangent_k+1 * (t_k+1 - t_k)
  
        result[i] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;
      }
  
      return result;
    };
  
    /*********************************/
    /********** INTERNALS ************/
    /*********************************/
  
    /* CONSTANTS */
  
    var WEBGL_CONSTANTS = {
      FLOAT: 5126,
      //FLOAT_MAT2: 35674,
      FLOAT_MAT3: 35675,
      FLOAT_MAT4: 35676,
      FLOAT_VEC2: 35664,
      FLOAT_VEC3: 35665,
      FLOAT_VEC4: 35666,
      LINEAR: 9729,
      REPEAT: 10497,
      SAMPLER_2D: 35678,
      POINTS: 0,
      LINES: 1,
      LINE_LOOP: 2,
      LINE_STRIP: 3,
      TRIANGLES: 4,
      TRIANGLE_STRIP: 5,
      TRIANGLE_FAN: 6,
      UNSIGNED_BYTE: 5121,
      UNSIGNED_SHORT: 5123,
    };
  
    var WEBGL_COMPONENT_TYPES = {
      5120: Int8Array,
      5121: Uint8Array,
      5122: Int16Array,
      5123: Uint16Array,
      5125: Uint32Array,
      5126: Float32Array,
    };
  
    var WEBGL_FILTERS = {
      9728: NearestFilter,
      9729: LinearFilter,
      9984: NearestMipmapNearestFilter,
      9985: LinearMipmapNearestFilter,
      9986: NearestMipmapLinearFilter,
      9987: LinearMipmapLinearFilter,
    };
  
    var WEBGL_WRAPPINGS = {
      33071: ClampToEdgeWrapping,
      33648: MirroredRepeatWrapping,
      10497: RepeatWrapping,
    };
  
    var WEBGL_TYPE_SIZES = {
      SCALAR: 1,
      VEC2: 2,
      VEC3: 3,
      VEC4: 4,
      MAT2: 4,
      MAT3: 9,
      MAT4: 16,
    };
  
    var ATTRIBUTES = {
      POSITION: "position",
      NORMAL: "normal",
      TANGENT: "tangent",
      TEXCOORD_0: "uv",
      TEXCOORD_1: "uv2",
      COLOR_0: "color",
      WEIGHTS_0: "skinWeight",
      JOINTS_0: "skinIndex",
    };
  
    var PATH_PROPERTIES = {
      scale: "scale",
      translation: "position",
      rotation: "quaternion",
      weights: "morphTargetInfluences",
    };
  
    var INTERPOLATION = {
      CUBICSPLINE: undefined, // We use a custom interpolant (GLTFCubicSplineInterpolation) for CUBICSPLINE tracks. Each
      // keyframe track will be initialized with a default interpolation type, then modified.
      LINEAR: InterpolateLinear,
      STEP: InterpolateDiscrete,
    };
  
    var ALPHA_MODES = {
      OPAQUE: "OPAQUE",
      MASK: "MASK",
      BLEND: "BLEND",
    };
  
    /* UTILITY FUNCTIONS */
  
    function resolveURL(url, path) {
      // Invalid URL
      if (typeof url !== "string" || url === "") return "";
  
      // Host Relative URL
      if (/^https?:\/\//i.test(path) && /^\//.test(url)) {
        path = path.replace(/(^https?:\/\/[^\/]+).*/i, "$1");
      }
  
      // Absolute URL http://,https://,//
      if (/^(https?:)?\/\//i.test(url)) return url;
  
      // Data URI
      if (/^data:.*,.*$/i.test(url)) return url;
  
      // Blob URL
      if (/^blob:.*$/i.test(url)) return url;
  
      // Relative URL
      return path + url;
    }
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
     */
    function createDefaultMaterial(cache) {
      if (cache["DefaultMaterial"] === undefined) {
        cache["DefaultMaterial"] = new MeshStandardMaterial({
          color: 0xffffff,
          emissive: 0x000000,
          metalness: 1,
          roughness: 1,
          transparent: false,
          depthTest: true,
          side: FrontSide,
        });
      }
  
      return cache["DefaultMaterial"];
    }
  
    function addUnknownExtensionsToUserData(knownExtensions, object, objectDef) {
      // Add unknown glTF extensions to an object's userData.
  
      for (var name in objectDef.extensions) {
        if (knownExtensions[name] === undefined) {
          object.userData.gltfExtensions = object.userData.gltfExtensions || {};
          object.userData.gltfExtensions[name] = objectDef.extensions[name];
        }
      }
    }
  
    /**
     * @param {Object3D|Material|BufferGeometry} object
     * @param {GLTF.definition} gltfDef
     */
    function assignExtrasToUserData(object, gltfDef) {
      if (gltfDef.extras !== undefined) {
        if (typeof gltfDef.extras === "object") {
          Object.assign(object.userData, gltfDef.extras);
        } else {
          console.warn(
            "THREE.GLTFLoader: Ignoring primitive type .extras, " + gltfDef.extras
          );
        }
      }
    }
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
     *
     * @param {BufferGeometry} geometry
     * @param {Array<GLTF.Target>} targets
     * @param {GLTFParser} parser
     * @return {Promise<BufferGeometry>}
     */
    function addMorphTargets(geometry, targets, parser) {
      var hasMorphPosition = false;
      var hasMorphNormal = false;
  
      for (var i = 0, il = targets.length; i < il; i++) {
        var target = targets[i];
  
        if (target.POSITION !== undefined) hasMorphPosition = true;
        if (target.NORMAL !== undefined) hasMorphNormal = true;
  
        if (hasMorphPosition && hasMorphNormal) break;
      }
  
      if (!hasMorphPosition && !hasMorphNormal) return Promise.resolve(geometry);
  
      var pendingPositionAccessors = [];
      var pendingNormalAccessors = [];
  
      for (var i = 0, il = targets.length; i < il; i++) {
        var target = targets[i];
  
        if (hasMorphPosition) {
          var pendingAccessor =
            target.POSITION !== undefined
              ? parser.getDependency("accessor", target.POSITION)
              : geometry.attributes.position;
  
          pendingPositionAccessors.push(pendingAccessor);
        }
  
        if (hasMorphNormal) {
          var pendingAccessor =
            target.NORMAL !== undefined
              ? parser.getDependency("accessor", target.NORMAL)
              : geometry.attributes.normal;
  
          pendingNormalAccessors.push(pendingAccessor);
        }
      }
  
      return Promise.all([
        Promise.all(pendingPositionAccessors),
        Promise.all(pendingNormalAccessors),
      ]).then(function (accessors) {
        var morphPositions = accessors[0];
        var morphNormals = accessors[1];
  
        if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
        if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;
        geometry.morphTargetsRelative = true;
  
        return geometry;
      });
    }
  
    /**
     * @param {Mesh} mesh
     * @param {GLTF.Mesh} meshDef
     */
    function updateMorphTargets(mesh, meshDef) {
      mesh.updateMorphTargets();
  
      if (meshDef.weights !== undefined) {
        for (var i = 0, il = meshDef.weights.length; i < il; i++) {
          mesh.morphTargetInfluences[i] = meshDef.weights[i];
        }
      }
  
      // .extras has user-defined data, so check that .extras.targetNames is an array.
      if (meshDef.extras && Array.isArray(meshDef.extras.targetNames)) {
        var targetNames = meshDef.extras.targetNames;
  
        if (mesh.morphTargetInfluences.length === targetNames.length) {
          mesh.morphTargetDictionary = {};
  
          for (var i = 0, il = targetNames.length; i < il; i++) {
            mesh.morphTargetDictionary[targetNames[i]] = i;
          }
        } else {
          console.warn(
            "THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names."
          );
        }
      }
    }
  
    function createPrimitiveKey(primitiveDef) {
      var dracoExtension =
        primitiveDef.extensions &&
        primitiveDef.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION];
      var geometryKey;
  
      if (dracoExtension) {
        geometryKey =
          "draco:" +
          dracoExtension.bufferView +
          ":" +
          dracoExtension.indices +
          ":" +
          createAttributesKey(dracoExtension.attributes);
      } else {
        geometryKey =
          primitiveDef.indices +
          ":" +
          createAttributesKey(primitiveDef.attributes) +
          ":" +
          primitiveDef.mode;
      }
  
      return geometryKey;
    }
  
    function createAttributesKey(attributes) {
      var attributesKey = "";
  
      var keys = Object.keys(attributes).sort();
  
      for (var i = 0, il = keys.length; i < il; i++) {
        attributesKey += keys[i] + ":" + attributes[keys[i]] + ";";
      }
  
      return attributesKey;
    }
  
    /* GLTF PARSER */
  
    function GLTFParser(json, options) {
      this.json = json || {};
      this.extensions = {};
      this.plugins = {};
      this.options = options || {};
  
      // loader object cache
      this.cache = new GLTFRegistry();
  
      // associations between Three.js objects and glTF elements
      this.associations = new Map();
  
      // BufferGeometry caching
      this.primitiveCache = {};
  
      // Object3D instance caches
      this.meshCache = { refs: {}, uses: {} };
      this.cameraCache = { refs: {}, uses: {} };
      this.lightCache = { refs: {}, uses: {} };
  
      // Track node names, to ensure no duplicates
      this.nodeNamesUsed = {};
  
      // Use an ImageBitmapLoader if imageBitmaps are supported. Moves much of the
      // expensive work of uploading a texture to the GPU off the main thread.
      if (
        typeof createImageBitmap !== "undefined" &&
        /Firefox/.test(navigator.userAgent) === false
      ) {
        this.textureLoader = new ImageBitmapLoader(this.options.manager);
      } else {
        this.textureLoader = new TextureLoader(this.options.manager);
      }
  
      this.textureLoader.setCrossOrigin(this.options.crossOrigin);
  
      this.fileLoader = new FileLoader(this.options.manager);
      this.fileLoader.setResponseType("arraybuffer");
  
      if (this.options.crossOrigin === "use-credentials") {
        this.fileLoader.setWithCredentials(true);
      }
    }
  
    GLTFParser.prototype.setExtensions = function (extensions) {
      this.extensions = extensions;
    };
  
    GLTFParser.prototype.setPlugins = function (plugins) {
      this.plugins = plugins;
    };
  
    GLTFParser.prototype.parse = function (onLoad, onError) {
      var parser = this;
      var json = this.json;
      var extensions = this.extensions;
  
      // Clear the loader cache
      this.cache.removeAll();
  
      // Mark the special nodes/meshes in json for efficient parse
      this._invokeAll(function (ext) {
        return ext._markDefs && ext._markDefs();
      });
  
      Promise.all([
        this.getDependencies("scene"),
        this.getDependencies("animation"),
        this.getDependencies("camera"),
      ])
        .then(function (dependencies) {
          var result = {
            scene: dependencies[0][json.scene || 0],
            scenes: dependencies[0],
            animations: dependencies[1],
            cameras: dependencies[2],
            asset: json.asset,
            parser: parser,
            userData: {},
          };
  
          addUnknownExtensionsToUserData(extensions, result, json);
  
          assignExtrasToUserData(result, json);
  
          onLoad(result);
        })
        .catch(onError);
    };
  
    /**
     * Marks the special nodes/meshes in json for efficient parse.
     */
    GLTFParser.prototype._markDefs = function () {
      var nodeDefs = this.json.nodes || [];
      var skinDefs = this.json.skins || [];
      var meshDefs = this.json.meshes || [];
  
      // Nothing in the node definition indicates whether it is a Bone or an
      // Object3D. Use the skins' joint references to mark bones.
      for (
        var skinIndex = 0, skinLength = skinDefs.length;
        skinIndex < skinLength;
        skinIndex++
      ) {
        var joints = skinDefs[skinIndex].joints;
  
        for (var i = 0, il = joints.length; i < il; i++) {
          nodeDefs[joints[i]].isBone = true;
        }
      }
  
      // Iterate over all nodes, marking references to shared resources,
      // as well as skeleton joints.
      for (
        var nodeIndex = 0, nodeLength = nodeDefs.length;
        nodeIndex < nodeLength;
        nodeIndex++
      ) {
        var nodeDef = nodeDefs[nodeIndex];
  
        if (nodeDef.mesh !== undefined) {
          this._addNodeRef(this.meshCache, nodeDef.mesh);
  
          // Nothing in the mesh definition indicates whether it is
          // a SkinnedMesh or Mesh. Use the node's mesh reference
          // to mark SkinnedMesh if node has skin.
          if (nodeDef.skin !== undefined) {
            meshDefs[nodeDef.mesh].isSkinnedMesh = true;
          }
        }
  
        if (nodeDef.camera !== undefined) {
          this._addNodeRef(this.cameraCache, nodeDef.camera);
        }
      }
    };
  
    /**
     * Counts references to shared node / Object3D resources. These resources
     * can be reused, or "instantiated", at multiple nodes in the scene
     * hierarchy. Mesh, Camera, and Light instances are instantiated and must
     * be marked. Non-scenegraph resources (like Materials, Geometries, and
     * Textures) can be reused directly and are not marked here.
     *
     * Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
     */
    GLTFParser.prototype._addNodeRef = function (cache, index) {
      if (index === undefined) return;
  
      if (cache.refs[index] === undefined) {
        cache.refs[index] = cache.uses[index] = 0;
      }
  
      cache.refs[index]++;
    };
  
    /** Returns a reference to a shared resource, cloning it if necessary. */
    GLTFParser.prototype._getNodeRef = function (cache, index, object) {
      if (cache.refs[index] <= 1) return object;
  
      var ref = object.clone();
  
      ref.name += "_instance_" + cache.uses[index]++;
  
      return ref;
    };
  
    GLTFParser.prototype._invokeOne = function (func) {
      var extensions = Object.values(this.plugins);
      extensions.push(this);
  
      for (var i = 0; i < extensions.length; i++) {
        var result = func(extensions[i]);
  
        if (result) return result;
      }
    };
  
    GLTFParser.prototype._invokeAll = function (func) {
      var extensions = Object.values(this.plugins);
      extensions.unshift(this);
  
      var pending = [];
  
      for (var i = 0; i < extensions.length; i++) {
        var result = func(extensions[i]);
  
        if (result) pending.push(result);
      }
  
      return pending;
    };
  
    /**
     * Requests the specified dependency asynchronously, with caching.
     * @param {string} type
     * @param {number} index
     * @return {Promise<Object3D|Material|THREE.Texture|AnimationClip|ArrayBuffer|Object>}
     */
    GLTFParser.prototype.getDependency = function (type, index) {
      var cacheKey = type + ":" + index;
      var dependency = this.cache.get(cacheKey);
  
      if (!dependency) {
        switch (type) {
          case "scene":
            dependency = this.loadScene(index);
            break;
  
          case "node":
            dependency = this.loadNode(index);
            break;
  
          case "mesh":
            dependency = this._invokeOne(function (ext) {
              return ext.loadMesh && ext.loadMesh(index);
            });
            break;
  
          case "accessor":
            dependency = this.loadAccessor(index);
            break;
  
          case "bufferView":
            dependency = this._invokeOne(function (ext) {
              return ext.loadBufferView && ext.loadBufferView(index);
            });
            break;
  
          case "buffer":
            dependency = this.loadBuffer(index);
            break;
  
          case "material":
            dependency = this._invokeOne(function (ext) {
              return ext.loadMaterial && ext.loadMaterial(index);
            });
            break;
  
          case "texture":
            dependency = this._invokeOne(function (ext) {
              return ext.loadTexture && ext.loadTexture(index);
            });
            break;
  
          case "skin":
            dependency = this.loadSkin(index);
            break;
  
          case "animation":
            dependency = this.loadAnimation(index);
            break;
  
          case "camera":
            dependency = this.loadCamera(index);
            break;
  
          default:
            throw new Error("Unknown type: " + type);
        }
  
        this.cache.add(cacheKey, dependency);
      }
  
      return dependency;
    };
  
    /**
     * Requests all dependencies of the specified type asynchronously, with caching.
     * @param {string} type
     * @return {Promise<Array<Object>>}
     */
    GLTFParser.prototype.getDependencies = function (type) {
      var dependencies = this.cache.get(type);
  
      if (!dependencies) {
        var parser = this;
        var defs = this.json[type + (type === "mesh" ? "es" : "s")] || [];
  
        dependencies = Promise.all(
          defs.map(function (def, index) {
            return parser.getDependency(type, index);
          })
        );
  
        this.cache.add(type, dependencies);
      }
  
      return dependencies;
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
     * @param {number} bufferIndex
     * @return {Promise<ArrayBuffer>}
     */
    GLTFParser.prototype.loadBuffer = function (bufferIndex) {
      var bufferDef = this.json.buffers[bufferIndex];
      var loader = this.fileLoader;
  
      if (bufferDef.type && bufferDef.type !== "arraybuffer") {
        throw new Error(
          "THREE.GLTFLoader: " + bufferDef.type + " buffer type is not supported."
        );
      }
  
      // If present, GLB container is required to be the first buffer.
      if (bufferDef.uri === undefined && bufferIndex === 0) {
        return Promise.resolve(this.extensions[EXTENSIONS.KHR_BINARY_GLTF].body);
      }
  
      var options = this.options;
  
      return new Promise(function (resolve, reject) {
        loader.load(
          resolveURL(bufferDef.uri, options.path),
          resolve,
          undefined,
          function () {
            reject(
              new Error(
                'THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".'
              )
            );
          }
        );
      });
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
     * @param {number} bufferViewIndex
     * @return {Promise<ArrayBuffer>}
     */
    GLTFParser.prototype.loadBufferView = function (bufferViewIndex) {
      var bufferViewDef = this.json.bufferViews[bufferViewIndex];
  
      return this.getDependency("buffer", bufferViewDef.buffer).then(function (
        buffer
      ) {
        var byteLength = bufferViewDef.byteLength || 0;
        var byteOffset = bufferViewDef.byteOffset || 0;
        return buffer.slice(byteOffset, byteOffset + byteLength);
      });
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
     * @param {number} accessorIndex
     * @return {Promise<BufferAttribute|InterleavedBufferAttribute>}
     */
    GLTFParser.prototype.loadAccessor = function (accessorIndex) {
      var parser = this;
      var json = this.json;
  
      var accessorDef = this.json.accessors[accessorIndex];
  
      if (
        accessorDef.bufferView === undefined &&
        accessorDef.sparse === undefined
      ) {
        // Ignore empty accessors, which may be used to declare runtime
        // information about attributes coming from another source (e.g. Draco
        // compression extension).
        return Promise.resolve(null);
      }
  
      var pendingBufferViews = [];
  
      if (accessorDef.bufferView !== undefined) {
        pendingBufferViews.push(
          this.getDependency("bufferView", accessorDef.bufferView)
        );
      } else {
        pendingBufferViews.push(null);
      }
  
      if (accessorDef.sparse !== undefined) {
        pendingBufferViews.push(
          this.getDependency("bufferView", accessorDef.sparse.indices.bufferView)
        );
        pendingBufferViews.push(
          this.getDependency("bufferView", accessorDef.sparse.values.bufferView)
        );
      }
  
      return Promise.all(pendingBufferViews).then(function (bufferViews) {
        var bufferView = bufferViews[0];
  
        var itemSize = WEBGL_TYPE_SIZES[accessorDef.type];
        var TypedArray = WEBGL_COMPONENT_TYPES[accessorDef.componentType];
  
        // For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.
        var elementBytes = TypedArray.BYTES_PER_ELEMENT;
        var itemBytes = elementBytes * itemSize;
        var byteOffset = accessorDef.byteOffset || 0;
        var byteStride =
          accessorDef.bufferView !== undefined
            ? json.bufferViews[accessorDef.bufferView].byteStride
            : undefined;
        var normalized = accessorDef.normalized === true;
        var array, bufferAttribute;
  
        // The buffer is not interleaved if the stride is the item size in bytes.
        if (byteStride && byteStride !== itemBytes) {
          // Each "slice" of the buffer, as defined by 'count' elements of 'byteStride' bytes, gets its own InterleavedBuffer
          // This makes sure that IBA.count reflects accessor.count properly
          var ibSlice = Math.floor(byteOffset / byteStride);
          var ibCacheKey =
            "InterleavedBuffer:" +
            accessorDef.bufferView +
            ":" +
            accessorDef.componentType +
            ":" +
            ibSlice +
            ":" +
            accessorDef.count;
          var ib = parser.cache.get(ibCacheKey);
  
          if (!ib) {
            array = new TypedArray(
              bufferView,
              ibSlice * byteStride,
              (accessorDef.count * byteStride) / elementBytes
            );
  
            // Integer parameters to IB/IBA are in array elements, not bytes.
            ib = new InterleavedBuffer(array, byteStride / elementBytes);
  
            parser.cache.add(ibCacheKey, ib);
          }
  
          bufferAttribute = new InterleavedBufferAttribute(
            ib,
            itemSize,
            (byteOffset % byteStride) / elementBytes,
            normalized
          );
        } else {
          if (bufferView === null) {
            array = new TypedArray(accessorDef.count * itemSize);
          } else {
            array = new TypedArray(
              bufferView,
              byteOffset,
              accessorDef.count * itemSize
            );
          }
  
          bufferAttribute = new BufferAttribute(array, itemSize, normalized);
        }
  
        // https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
        if (accessorDef.sparse !== undefined) {
          var itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
          var TypedArrayIndices =
            WEBGL_COMPONENT_TYPES[accessorDef.sparse.indices.componentType];
  
          var byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
          var byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;
  
          var sparseIndices = new TypedArrayIndices(
            bufferViews[1],
            byteOffsetIndices,
            accessorDef.sparse.count * itemSizeIndices
          );
          var sparseValues = new TypedArray(
            bufferViews[2],
            byteOffsetValues,
            accessorDef.sparse.count * itemSize
          );
  
          if (bufferView !== null) {
            // Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
            bufferAttribute = new BufferAttribute(
              bufferAttribute.array.slice(),
              bufferAttribute.itemSize,
              bufferAttribute.normalized
            );
          }
  
          for (var i = 0, il = sparseIndices.length; i < il; i++) {
            var index = sparseIndices[i];
  
            bufferAttribute.setX(index, sparseValues[i * itemSize]);
            if (itemSize >= 2)
              bufferAttribute.setY(index, sparseValues[i * itemSize + 1]);
            if (itemSize >= 3)
              bufferAttribute.setZ(index, sparseValues[i * itemSize + 2]);
            if (itemSize >= 4)
              bufferAttribute.setW(index, sparseValues[i * itemSize + 3]);
            if (itemSize >= 5)
              throw new Error(
                "THREE.GLTFLoader: Unsupported itemSize in sparse BufferAttribute."
              );
          }
        }
  
        return bufferAttribute;
      });
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
     * @param {number} textureIndex
     * @return {Promise<THREE.Texture>}
     */
    GLTFParser.prototype.loadTexture = function (textureIndex) {
      var parser = this;
      var json = this.json;
      var options = this.options;
  
      var textureDef = json.textures[textureIndex];
  
      var textureExtensions = textureDef.extensions || {};
  
      var source;
  
      if (textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]) {
        source =
          json.images[textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS].source];
      } else {
        source = json.images[textureDef.source];
      }
  
      var loader;
  
      if (source.uri) {
        loader = options.manager.getHandler(source.uri);
      }
  
      if (!loader) {
        loader = textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]
          ? parser.extensions[EXTENSIONS.MSFT_TEXTURE_DDS].ddsLoader
          : this.textureLoader;
      }
  
      return this.loadTextureImage(textureIndex, source, loader);
    };
  
    GLTFParser.prototype.loadTextureImage = function (
      textureIndex,
      source,
      loader
    ) {
      var parser = this;
      var json = this.json;
      var options = this.options;
  
      var textureDef = json.textures[textureIndex];
  
      var URL = self.URL || self.webkitURL;
  
      var sourceURI = source.uri;
      var isObjectURL = false;
      var hasAlpha = true;
  
      if (source.mimeType === "image/jpeg") hasAlpha = false;
  
      if (source.bufferView !== undefined) {
        // Load binary image data from bufferView, if provided.
  
        sourceURI = parser
          .getDependency("bufferView", source.bufferView)
          .then(function (bufferView) {
            if (source.mimeType === "image/png") {
              // Inspect the PNG 'IHDR' chunk to determine whether the image could have an
              // alpha channel. This check is conservative — the image could have an alpha
              // channel with all values == 1, and the indexed type (colorType == 3) only
              // sometimes contains alpha.
              //
              // https://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header
              var colorType = new DataView(bufferView, 25, 1).getUint8(0, false);
              hasAlpha = colorType === 6 || colorType === 4 || colorType === 3;
            }
  
            isObjectURL = true;
            var blob = new Blob([bufferView], { type: source.mimeType });
            sourceURI = URL.createObjectURL(blob);
            return sourceURI;
          });
      }
  
      return Promise.resolve(sourceURI)
        .then(function (sourceURI) {
          return new Promise(function (resolve, reject) {
            var onLoad = resolve;
  
            if (loader.isImageBitmapLoader === true) {
              onLoad = function (imageBitmap) {
                resolve(new CanvasTexture(imageBitmap));
              };
            }
  
            loader.load(
              resolveURL(sourceURI, options.path),
              onLoad,
              undefined,
              reject
            );
          });
        })
        .then(function (texture) {
          // Clean up resources and configure Texture.
  
          if (isObjectURL === true) {
            URL.revokeObjectURL(sourceURI);
          }
  
          texture.flipY = false;
  
          if (textureDef.name) texture.name = textureDef.name;
  
          // When there is definitely no alpha channel in the texture, set RGBFormat to save space.
          if (!hasAlpha) texture.format = RGBFormat;
  
          var samplers = json.samplers || {};
          var sampler = samplers[textureDef.sampler] || {};
  
          texture.magFilter = WEBGL_FILTERS[sampler.magFilter] || LinearFilter;
          texture.minFilter =
            WEBGL_FILTERS[sampler.minFilter] || LinearMipmapLinearFilter;
          texture.wrapS = WEBGL_WRAPPINGS[sampler.wrapS] || RepeatWrapping;
          texture.wrapT = WEBGL_WRAPPINGS[sampler.wrapT] || RepeatWrapping;
  
          parser.associations.set(texture, {
            type: "textures",
            index: textureIndex,
          });
  
          return texture;
        });
    };
  
    /**
     * Asynchronously assigns a texture to the given material parameters.
     * @param {Object} materialParams
     * @param {string} mapName
     * @param {Object} mapDef
     * @return {Promise}
     */
    GLTFParser.prototype.assignTexture = function (
      materialParams,
      mapName,
      mapDef
    ) {
      var parser = this;
  
      return this.getDependency("texture", mapDef.index).then(function (texture) {
        // Materials sample aoMap from UV set 1 and other maps from UV set 0 - this can't be configured
        // However, we will copy UV set 0 to UV set 1 on demand for aoMap
        if (
          mapDef.texCoord !== undefined &&
          mapDef.texCoord != 0 &&
          !(mapName === "aoMap" && mapDef.texCoord == 1)
        ) {
          console.warn(
            "THREE.GLTFLoader: Custom UV set " +
              mapDef.texCoord +
              " for texture " +
              mapName +
              " not yet supported."
          );
        }
  
        if (parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]) {
          var transform =
            mapDef.extensions !== undefined
              ? mapDef.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]
              : undefined;
  
          if (transform) {
            var gltfReference = parser.associations.get(texture);
            texture = parser.extensions[
              EXTENSIONS.KHR_TEXTURE_TRANSFORM
            ].extendTexture(texture, transform);
            parser.associations.set(texture, gltfReference);
          }
        }
  
        materialParams[mapName] = texture;
      });
    };
  
    /**
     * Assigns final material to a Mesh, Line, or Points instance. The instance
     * already has a material (generated from the glTF material options alone)
     * but reuse of the same glTF material may require multiple threejs materials
     * to accomodate different primitive types, defines, etc. New materials will
     * be created if necessary, and reused from a cache.
     * @param  {Object3D} mesh Mesh, Line, or Points instance.
     */
    GLTFParser.prototype.assignFinalMaterial = function (mesh) {
      var geometry = mesh.geometry;
      var material = mesh.material;
  
      var useVertexTangents = geometry.attributes.tangent !== undefined;
      var useVertexColors = geometry.attributes.color !== undefined;
      var useFlatShading = geometry.attributes.normal === undefined;
      var useSkinning = mesh.isSkinnedMesh === true;
      var useMorphTargets = Object.keys(geometry.morphAttributes).length > 0;
      var useMorphNormals =
        useMorphTargets && geometry.morphAttributes.normal !== undefined;
  
      if (mesh.isPoints) {
        var cacheKey = "PointsMaterial:" + material.uuid;
  
        var pointsMaterial = this.cache.get(cacheKey);
  
        if (!pointsMaterial) {
          pointsMaterial = new PointsMaterial();
          Material.prototype.copy.call(pointsMaterial, material);
          pointsMaterial.color.copy(material.color);
          pointsMaterial.map = material.map;
          pointsMaterial.sizeAttenuation = false; // glTF spec says points should be 1px
  
          this.cache.add(cacheKey, pointsMaterial);
        }
  
        material = pointsMaterial;
      } else if (mesh.isLine) {
        var cacheKey = "LineBasicMaterial:" + material.uuid;
  
        var lineMaterial = this.cache.get(cacheKey);
  
        if (!lineMaterial) {
          lineMaterial = new LineBasicMaterial();
          Material.prototype.copy.call(lineMaterial, material);
          lineMaterial.color.copy(material.color);
  
          this.cache.add(cacheKey, lineMaterial);
        }
  
        material = lineMaterial;
      }
  
      // Clone the material if it will be modified
      if (
        useVertexTangents ||
        useVertexColors ||
        useFlatShading ||
        useSkinning ||
        useMorphTargets
      ) {
        var cacheKey = "ClonedMaterial:" + material.uuid + ":";
  
        if (material.isGLTFSpecularGlossinessMaterial)
          cacheKey += "specular-glossiness:";
        if (useSkinning) cacheKey += "skinning:";
        if (useVertexTangents) cacheKey += "vertex-tangents:";
        if (useVertexColors) cacheKey += "vertex-colors:";
        if (useFlatShading) cacheKey += "flat-shading:";
        if (useMorphTargets) cacheKey += "morph-targets:";
        if (useMorphNormals) cacheKey += "morph-normals:";
  
        var cachedMaterial = this.cache.get(cacheKey);
  
        if (!cachedMaterial) {
          cachedMaterial = material.clone();
  
          if (useSkinning) cachedMaterial.skinning = true;
          if (useVertexTangents) cachedMaterial.vertexTangents = true;
          if (useVertexColors) cachedMaterial.vertexColors = true;
          if (useFlatShading) cachedMaterial.flatShading = true;
          if (useMorphTargets) cachedMaterial.morphTargets = true;
          if (useMorphNormals) cachedMaterial.morphNormals = true;
  
          this.cache.add(cacheKey, cachedMaterial);
  
          this.associations.set(cachedMaterial, this.associations.get(material));
        }
  
        material = cachedMaterial;
      }
  
      // workarounds for mesh and geometry
  
      if (
        material.aoMap &&
        geometry.attributes.uv2 === undefined &&
        geometry.attributes.uv !== undefined
      ) {
        geometry.setAttribute("uv2", geometry.attributes.uv);
      }
  
      // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
      if (material.normalScale && !useVertexTangents) {
        material.normalScale.y = -material.normalScale.y;
      }
  
      if (material.clearcoatNormalScale && !useVertexTangents) {
        material.clearcoatNormalScale.y = -material.clearcoatNormalScale.y;
      }
  
      mesh.material = material;
    };
  
    GLTFParser.prototype.getMaterialType = function (/* materialIndex */) {
      return MeshStandardMaterial;
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
     * @param {number} materialIndex
     * @return {Promise<Material>}
     */
    GLTFParser.prototype.loadMaterial = function (materialIndex) {
      var parser = this;
      var json = this.json;
      var extensions = this.extensions;
      var materialDef = json.materials[materialIndex];
  
      var materialType;
      var materialParams = {};
      var materialExtensions = materialDef.extensions || {};
  
      var pending = [];
  
      if (materialExtensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS]) {
        var sgExtension =
          extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS];
        materialType = sgExtension.getMaterialType();
        pending.push(
          sgExtension.extendParams(materialParams, materialDef, parser)
        );
      } else if (materialExtensions[EXTENSIONS.KHR_MATERIALS_UNLIT]) {
        var kmuExtension = extensions[EXTENSIONS.KHR_MATERIALS_UNLIT];
        materialType = kmuExtension.getMaterialType();
        pending.push(
          kmuExtension.extendParams(materialParams, materialDef, parser)
        );
      } else {
        // Specification:
        // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material
  
        var metallicRoughness = materialDef.pbrMetallicRoughness || {};
  
        materialParams.color = new Color(1.0, 1.0, 1.0);
        materialParams.opacity = 1.0;
  
        if (Array.isArray(metallicRoughness.baseColorFactor)) {
          var array = metallicRoughness.baseColorFactor;
  
          materialParams.color.fromArray(array);
          materialParams.opacity = array[3];
        }
  
        if (metallicRoughness.baseColorTexture !== undefined) {
          pending.push(
            parser.assignTexture(
              materialParams,
              "map",
              metallicRoughness.baseColorTexture
            )
          );
        }
  
        materialParams.metalness =
          metallicRoughness.metallicFactor !== undefined
            ? metallicRoughness.metallicFactor
            : 1.0;
        materialParams.roughness =
          metallicRoughness.roughnessFactor !== undefined
            ? metallicRoughness.roughnessFactor
            : 1.0;
  
        if (metallicRoughness.metallicRoughnessTexture !== undefined) {
          pending.push(
            parser.assignTexture(
              materialParams,
              "metalnessMap",
              metallicRoughness.metallicRoughnessTexture
            )
          );
          pending.push(
            parser.assignTexture(
              materialParams,
              "roughnessMap",
              metallicRoughness.metallicRoughnessTexture
            )
          );
        }
  
        materialType = this._invokeOne(function (ext) {
          return ext.getMaterialType && ext.getMaterialType(materialIndex);
        });
  
        pending.push(
          Promise.all(
            this._invokeAll(function (ext) {
              return (
                ext.extendMaterialParams &&
                ext.extendMaterialParams(materialIndex, materialParams)
              );
            })
          )
        );
      }
  
      if (materialDef.doubleSided === true) {
        materialParams.side = DoubleSide;
      }
  
      var alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;
  
      if (alphaMode === ALPHA_MODES.BLEND) {
        materialParams.transparent = true;
  
        // See: https://github.com/mrdoob/three.js/issues/17706
        materialParams.depthWrite = false;
      } else {
        materialParams.transparent = false;
  
        if (alphaMode === ALPHA_MODES.MASK) {
          materialParams.alphaTest =
            materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;
        }
      }
  
      if (
        materialDef.normalTexture !== undefined &&
        materialType !== MeshBasicMaterial
      ) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "normalMap",
            materialDef.normalTexture
          )
        );
  
        materialParams.normalScale = new Vector2(1, 1);
  
        if (materialDef.normalTexture.scale !== undefined) {
          materialParams.normalScale.set(
            materialDef.normalTexture.scale,
            materialDef.normalTexture.scale
          );
        }
      }
  
      if (
        materialDef.occlusionTexture !== undefined &&
        materialType !== MeshBasicMaterial
      ) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "aoMap",
            materialDef.occlusionTexture
          )
        );
  
        if (materialDef.occlusionTexture.strength !== undefined) {
          materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;
        }
      }
  
      if (
        materialDef.emissiveFactor !== undefined &&
        materialType !== MeshBasicMaterial
      ) {
        materialParams.emissive = new Color().fromArray(
          materialDef.emissiveFactor
        );
      }
  
      if (
        materialDef.emissiveTexture !== undefined &&
        materialType !== MeshBasicMaterial
      ) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "emissiveMap",
            materialDef.emissiveTexture
          )
        );
      }
  
      return Promise.all(pending).then(function () {
        var material;
  
        if (materialType === GLTFMeshStandardSGMaterial) {
          material = extensions[
            EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS
          ].createMaterial(materialParams);
        } else {
          material = new materialType(materialParams);
        }
  
        if (materialDef.name) material.name = materialDef.name;
  
        // baseColorTexture, emissiveTexture, and specularGlossinessTexture use sRGB encoding.
        if (material.map) material.map.encoding = sRGBEncoding;
        if (material.emissiveMap) material.emissiveMap.encoding = sRGBEncoding;
  
        assignExtrasToUserData(material, materialDef);
  
        parser.associations.set(material, {
          type: "materials",
          index: materialIndex,
        });
  
        if (materialDef.extensions)
          addUnknownExtensionsToUserData(extensions, material, materialDef);
  
        return material;
      });
    };
  
    /** When Object3D instances are targeted by animation, they need unique names. */
    GLTFParser.prototype.createUniqueName = function (originalName) {
      var name = PropertyBinding.sanitizeNodeName(originalName || "");
  
      for (var i = 1; this.nodeNamesUsed[name]; ++i) {
        name = originalName + "_" + i;
      }
  
      this.nodeNamesUsed[name] = true;
  
      return name;
    };
  
    /**
     * @param {BufferGeometry} geometry
     * @param {GLTF.Primitive} primitiveDef
     * @param {GLTFParser} parser
     */
    function computeBounds(geometry, primitiveDef, parser) {
      var attributes = primitiveDef.attributes;
  
      var box = new Box3();
  
      if (attributes.POSITION !== undefined) {
        var accessor = parser.json.accessors[attributes.POSITION];
  
        var min = accessor.min;
        var max = accessor.max;
  
        // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.
  
        if (min !== undefined && max !== undefined) {
          box.set(
            new Vector3(min[0], min[1], min[2]),
            new Vector3(max[0], max[1], max[2])
          );
        } else {
          console.warn(
            "THREE.GLTFLoader: Missing min/max properties for accessor POSITION."
          );
  
          return;
        }
      } else {
        return;
      }
  
      var targets = primitiveDef.targets;
  
      if (targets !== undefined) {
        var maxDisplacement = new Vector3();
        var vector = new Vector3();
  
        for (var i = 0, il = targets.length; i < il; i++) {
          var target = targets[i];
  
          if (target.POSITION !== undefined) {
            var accessor = parser.json.accessors[target.POSITION];
            var min = accessor.min;
            var max = accessor.max;
  
            // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.
  
            if (min !== undefined && max !== undefined) {
              // we need to get max of absolute components because target weight is [-1,1]
              vector.setX(Math.max(Math.abs(min[0]), Math.abs(max[0])));
              vector.setY(Math.max(Math.abs(min[1]), Math.abs(max[1])));
              vector.setZ(Math.max(Math.abs(min[2]), Math.abs(max[2])));
  
              // Note: this assumes that the sum of all weights is at most 1. This isn't quite correct - it's more conservative
              // to assume that each target can have a max weight of 1. However, for some use cases - notably, when morph targets
              // are used to implement key-frame animations and as such only two are active at a time - this results in very large
              // boxes. So for now we make a box that's sometimes a touch too small but is hopefully mostly of reasonable size.
              maxDisplacement.max(vector);
            } else {
              console.warn(
                "THREE.GLTFLoader: Missing min/max properties for accessor POSITION."
              );
            }
          }
        }
  
        // As per comment above this box isn't conservative, but has a reasonable size for a very large number of morph targets.
        box.expandByVector(maxDisplacement);
      }
  
      geometry.boundingBox = box;
  
      var sphere = new Sphere();
  
      box.getCenter(sphere.center);
      sphere.radius = box.min.distanceTo(box.max) / 2;
  
      geometry.boundingSphere = sphere;
    }
  
    /**
     * @param {BufferGeometry} geometry
     * @param {GLTF.Primitive} primitiveDef
     * @param {GLTFParser} parser
     * @return {Promise<BufferGeometry>}
     */
    function addPrimitiveAttributes(geometry, primitiveDef, parser) {
      var attributes = primitiveDef.attributes;
  
      var pending = [];
  
      function assignAttributeAccessor(accessorIndex, attributeName) {
        return parser
          .getDependency("accessor", accessorIndex)
          .then(function (accessor) {
            geometry.setAttribute(attributeName, accessor);
          });
      }
  
      for (var gltfAttributeName in attributes) {
        var threeAttributeName =
          ATTRIBUTES[gltfAttributeName] || gltfAttributeName.toLowerCase();
  
        // Skip attributes already provided by e.g. Draco extension.
        if (threeAttributeName in geometry.attributes) continue;
  
        pending.push(
          assignAttributeAccessor(
            attributes[gltfAttributeName],
            threeAttributeName
          )
        );
      }
  
      if (primitiveDef.indices !== undefined && !geometry.index) {
        var accessor = parser
          .getDependency("accessor", primitiveDef.indices)
          .then(function (accessor) {
            geometry.setIndex(accessor);
          });
  
        pending.push(accessor);
      }
  
      assignExtrasToUserData(geometry, primitiveDef);
  
      computeBounds(geometry, primitiveDef, parser);
  
      return Promise.all(pending).then(function () {
        return primitiveDef.targets !== undefined
          ? addMorphTargets(geometry, primitiveDef.targets, parser)
          : geometry;
      });
    }
  
    /**
     * @param {BufferGeometry} geometry
     * @param {Number} drawMode
     * @return {BufferGeometry}
     */
    function toTrianglesDrawMode(geometry, drawMode) {
      var index = geometry.getIndex();
  
      // generate index if not present
  
      if (index === null) {
        var indices = [];
  
        var position = geometry.getAttribute("position");
  
        if (position !== undefined) {
          for (var i = 0; i < position.count; i++) {
            indices.push(i);
          }
  
          geometry.setIndex(indices);
          index = geometry.getIndex();
        } else {
          console.error(
            "THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible."
          );
          return geometry;
        }
      }
  
      //
  
      var numberOfTriangles = index.count - 2;
      var newIndices = [];
  
      if (drawMode === TriangleFanDrawMode) {
        // gl.TRIANGLE_FAN
  
        for (var i = 1; i <= numberOfTriangles; i++) {
          newIndices.push(index.getX(0));
          newIndices.push(index.getX(i));
          newIndices.push(index.getX(i + 1));
        }
      } else {
        // gl.TRIANGLE_STRIP
  
        for (var i = 0; i < numberOfTriangles; i++) {
          if (i % 2 === 0) {
            newIndices.push(index.getX(i));
            newIndices.push(index.getX(i + 1));
            newIndices.push(index.getX(i + 2));
          } else {
            newIndices.push(index.getX(i + 2));
            newIndices.push(index.getX(i + 1));
            newIndices.push(index.getX(i));
          }
        }
      }
  
      if (newIndices.length / 3 !== numberOfTriangles) {
        console.error(
          "THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles."
        );
      }
  
      // build final geometry
  
      var newGeometry = geometry.clone();
      newGeometry.setIndex(newIndices);
  
      return newGeometry;
    }
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
     *
     * Creates BufferGeometries from primitives.
     *
     * @param {Array<GLTF.Primitive>} primitives
     * @return {Promise<Array<BufferGeometry>>}
     */
    GLTFParser.prototype.loadGeometries = function (primitives) {
      var parser = this;
      var extensions = this.extensions;
      var cache = this.primitiveCache;
  
      function createDracoPrimitive(primitive) {
        return extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
          .decodePrimitive(primitive, parser)
          .then(function (geometry) {
            return addPrimitiveAttributes(geometry, primitive, parser);
          });
      }
  
      var pending = [];
  
      for (var i = 0, il = primitives.length; i < il; i++) {
        var primitive = primitives[i];
        var cacheKey = createPrimitiveKey(primitive);
  
        // See if we've already created this geometry
        var cached = cache[cacheKey];
  
        if (cached) {
          // Use the cached geometry if it exists
          pending.push(cached.promise);
        } else {
          var geometryPromise;
  
          if (
            primitive.extensions &&
            primitive.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
          ) {
            // Use DRACO geometry if available
            geometryPromise = createDracoPrimitive(primitive);
          } else {
            // Otherwise create a new geometry
            geometryPromise = addPrimitiveAttributes(
              new BufferGeometry(),
              primitive,
              parser
            );
          }
  
          // Cache this geometry
          cache[cacheKey] = { primitive: primitive, promise: geometryPromise };
  
          pending.push(geometryPromise);
        }
      }
  
      return Promise.all(pending);
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
     * @param {number} meshIndex
     * @return {Promise<Group|Mesh|SkinnedMesh>}
     */
    GLTFParser.prototype.loadMesh = function (meshIndex) {
      var parser = this;
      var json = this.json;
  
      var meshDef = json.meshes[meshIndex];
      var primitives = meshDef.primitives;
  
      var pending = [];
  
      for (var i = 0, il = primitives.length; i < il; i++) {
        var material =
          primitives[i].material === undefined
            ? createDefaultMaterial(this.cache)
            : this.getDependency("material", primitives[i].material);
  
        pending.push(material);
      }
  
      pending.push(parser.loadGeometries(primitives));
  
      return Promise.all(pending).then(function (results) {
        var materials = results.slice(0, results.length - 1);
        var geometries = results[results.length - 1];
  
        var meshes = [];
  
        for (var i = 0, il = geometries.length; i < il; i++) {
          var geometry = geometries[i];
          var primitive = primitives[i];
  
          // 1. create Mesh
  
          var mesh;
  
          var material = materials[i];
  
          if (
            primitive.mode === WEBGL_CONSTANTS.TRIANGLES ||
            primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ||
            primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ||
            primitive.mode === undefined
          ) {
            // .isSkinnedMesh isn't in glTF spec. See ._markDefs()
            mesh =
              meshDef.isSkinnedMesh === true
                ? new SkinnedMesh(geometry, material)
                : new Mesh(geometry, material);
  
            if (
              mesh.isSkinnedMesh === true &&
              !mesh.geometry.attributes.skinWeight.normalized
            ) {
              // we normalize floating point skin weight array to fix malformed assets (see #15319)
              // it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
              mesh.normalizeSkinWeights();
            }
  
            if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP) {
              mesh.geometry = toTrianglesDrawMode(
                mesh.geometry,
                TriangleStripDrawMode
              );
            } else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {
              mesh.geometry = toTrianglesDrawMode(
                mesh.geometry,
                TriangleFanDrawMode
              );
            }
          } else if (primitive.mode === WEBGL_CONSTANTS.LINES) {
            mesh = new LineSegments(geometry, material);
          } else if (primitive.mode === WEBGL_CONSTANTS.LINE_STRIP) {
            mesh = new Line(geometry, material);
          } else if (primitive.mode === WEBGL_CONSTANTS.LINE_LOOP) {
            mesh = new LineLoop(geometry, material);
          } else if (primitive.mode === WEBGL_CONSTANTS.POINTS) {
            mesh = new Points(geometry, material);
          } else {
            throw new Error(
              "THREE.GLTFLoader: Primitive mode unsupported: " + primitive.mode
            );
          }
  
          if (Object.keys(mesh.geometry.morphAttributes).length > 0) {
            updateMorphTargets(mesh, meshDef);
          }
  
          mesh.name = parser.createUniqueName(
            meshDef.name || "mesh_" + meshIndex
          );
  
          assignExtrasToUserData(mesh, meshDef);
  
          parser.assignFinalMaterial(mesh);
  
          meshes.push(mesh);
        }
  
        if (meshes.length === 1) {
          return meshes[0];
        }
  
        var group = new Group();
  
        for (var i = 0, il = meshes.length; i < il; i++) {
          group.add(meshes[i]);
        }
  
        return group;
      });
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
     * @param {number} cameraIndex
     * @return {Promise<THREE.Camera>}
     */
    GLTFParser.prototype.loadCamera = function (cameraIndex) {
      var camera;
      var cameraDef = this.json.cameras[cameraIndex];
      var params = cameraDef[cameraDef.type];
  
      if (!params) {
        console.warn("THREE.GLTFLoader: Missing camera parameters.");
        return;
      }
  
      if (cameraDef.type === "perspective") {
        camera = new PerspectiveCamera(
          MathUtils.radToDeg(params.yfov),
          params.aspectRatio || 1,
          params.znear || 1,
          params.zfar || 2e6
        );
      } else if (cameraDef.type === "orthographic") {
        camera = new OrthographicCamera(
          -params.xmag,
          params.xmag,
          params.ymag,
          -params.ymag,
          params.znear,
          params.zfar
        );
      }
  
      if (cameraDef.name) camera.name = this.createUniqueName(cameraDef.name);
  
      assignExtrasToUserData(camera, cameraDef);
  
      return Promise.resolve(camera);
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
     * @param {number} skinIndex
     * @return {Promise<Object>}
     */
    GLTFParser.prototype.loadSkin = function (skinIndex) {
      var skinDef = this.json.skins[skinIndex];
  
      var skinEntry = { joints: skinDef.joints };
  
      if (skinDef.inverseBindMatrices === undefined) {
        return Promise.resolve(skinEntry);
      }
  
      return this.getDependency("accessor", skinDef.inverseBindMatrices).then(
        function (accessor) {
          skinEntry.inverseBindMatrices = accessor;
  
          return skinEntry;
        }
      );
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
     * @param {number} animationIndex
     * @return {Promise<AnimationClip>}
     */
    GLTFParser.prototype.loadAnimation = function (animationIndex) {
      var json = this.json;
  
      var animationDef = json.animations[animationIndex];
  
      var pendingNodes = [];
      var pendingInputAccessors = [];
      var pendingOutputAccessors = [];
      var pendingSamplers = [];
      var pendingTargets = [];
  
      for (var i = 0, il = animationDef.channels.length; i < il; i++) {
        var channel = animationDef.channels[i];
        var sampler = animationDef.samplers[channel.sampler];
        var target = channel.target;
        var name = target.node !== undefined ? target.node : target.id; // NOTE: target.id is deprecated.
        var input =
          animationDef.parameters !== undefined
            ? animationDef.parameters[sampler.input]
            : sampler.input;
        var output =
          animationDef.parameters !== undefined
            ? animationDef.parameters[sampler.output]
            : sampler.output;
  
        pendingNodes.push(this.getDependency("node", name));
        pendingInputAccessors.push(this.getDependency("accessor", input));
        pendingOutputAccessors.push(this.getDependency("accessor", output));
        pendingSamplers.push(sampler);
        pendingTargets.push(target);
      }
  
      return Promise.all([
        Promise.all(pendingNodes),
        Promise.all(pendingInputAccessors),
        Promise.all(pendingOutputAccessors),
        Promise.all(pendingSamplers),
        Promise.all(pendingTargets),
      ]).then(function (dependencies) {
        var nodes = dependencies[0];
        var inputAccessors = dependencies[1];
        var outputAccessors = dependencies[2];
        var samplers = dependencies[3];
        var targets = dependencies[4];
  
        var tracks = [];
  
        for (var i = 0, il = nodes.length; i < il; i++) {
          var node = nodes[i];
          var inputAccessor = inputAccessors[i];
          var outputAccessor = outputAccessors[i];
          var sampler = samplers[i];
          var target = targets[i];
  
          if (node === undefined) continue;
  
          node.updateMatrix();
          node.matrixAutoUpdate = true;
  
          var TypedKeyframeTrack;
  
          switch (PATH_PROPERTIES[target.path]) {
            case PATH_PROPERTIES.weights:
              TypedKeyframeTrack = NumberKeyframeTrack;
              break;
  
            case PATH_PROPERTIES.rotation:
              TypedKeyframeTrack = QuaternionKeyframeTrack;
              break;
  
            case PATH_PROPERTIES.position:
            case PATH_PROPERTIES.scale:
            default:
              TypedKeyframeTrack = VectorKeyframeTrack;
              break;
          }
  
          var targetName = node.name ? node.name : node.uuid;
  
          var interpolation =
            sampler.interpolation !== undefined
              ? INTERPOLATION[sampler.interpolation]
              : InterpolateLinear;
  
          var targetNames = [];
  
          if (PATH_PROPERTIES[target.path] === PATH_PROPERTIES.weights) {
            // Node may be a Group (glTF mesh with several primitives) or a Mesh.
            node.traverse(function (object) {
              if (object.isMesh === true && object.morphTargetInfluences) {
                targetNames.push(object.name ? object.name : object.uuid);
              }
            });
          } else {
            targetNames.push(targetName);
          }
  
          var outputArray = outputAccessor.array;
  
          if (outputAccessor.normalized) {
            var scale;
  
            if (outputArray.constructor === Int8Array) {
              scale = 1 / 127;
            } else if (outputArray.constructor === Uint8Array) {
              scale = 1 / 255;
            } else if (outputArray.constructor == Int16Array) {
              scale = 1 / 32767;
            } else if (outputArray.constructor === Uint16Array) {
              scale = 1 / 65535;
            } else {
              throw new Error(
                "THREE.GLTFLoader: Unsupported output accessor component type."
              );
            }
  
            var scaled = new Float32Array(outputArray.length);
  
            for (var j = 0, jl = outputArray.length; j < jl; j++) {
              scaled[j] = outputArray[j] * scale;
            }
  
            outputArray = scaled;
          }
  
          for (var j = 0, jl = targetNames.length; j < jl; j++) {
            var track = new TypedKeyframeTrack(
              targetNames[j] + "." + PATH_PROPERTIES[target.path],
              inputAccessor.array,
              outputArray,
              interpolation
            );
  
            // Override interpolation with custom factory method.
            if (sampler.interpolation === "CUBICSPLINE") {
              track.createInterpolant = function InterpolantFactoryMethodGLTFCubicSpline(
                result
              ) {
                // A CUBICSPLINE keyframe in glTF has three output values for each input value,
                // representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
                // must be divided by three to get the interpolant's sampleSize argument.
  
                return new GLTFCubicSplineInterpolant(
                  this.times,
                  this.values,
                  this.getValueSize() / 3,
                  result
                );
              };
  
              // Mark as CUBICSPLINE. `track.getInterpolation()` doesn't support custom interpolants.
              track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;
            }
  
            tracks.push(track);
          }
        }
  
        var name = animationDef.name
          ? animationDef.name
          : "animation_" + animationIndex;
  
        return new AnimationClip(name, undefined, tracks);
      });
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
     * @param {number} nodeIndex
     * @return {Promise<Object3D>}
     */
    GLTFParser.prototype.loadNode = function (nodeIndex) {
      var json = this.json;
      var extensions = this.extensions;
      var parser = this;
  
      var nodeDef = json.nodes[nodeIndex];
  
      // reserve node's name before its dependencies, so the root has the intended name.
      var nodeName = nodeDef.name ? parser.createUniqueName(nodeDef.name) : "";
  
      return (function () {
        var pending = [];
  
        if (nodeDef.mesh !== undefined) {
          pending.push(
            parser.getDependency("mesh", nodeDef.mesh).then(function (mesh) {
              var node = parser._getNodeRef(parser.meshCache, nodeDef.mesh, mesh);
  
              // if weights are provided on the node, override weights on the mesh.
              if (nodeDef.weights !== undefined) {
                node.traverse(function (o) {
                  if (!o.isMesh) return;
  
                  for (var i = 0, il = nodeDef.weights.length; i < il; i++) {
                    o.morphTargetInfluences[i] = nodeDef.weights[i];
                  }
                });
              }
  
              return node;
            })
          );
        }
  
        if (nodeDef.camera !== undefined) {
          pending.push(
            parser
              .getDependency("camera", nodeDef.camera)
              .then(function (camera) {
                return parser._getNodeRef(
                  parser.cameraCache,
                  nodeDef.camera,
                  camera
                );
              })
          );
        }
  
        parser
          ._invokeAll(function (ext) {
            return (
              ext.createNodeAttachment && ext.createNodeAttachment(nodeIndex)
            );
          })
          .forEach(function (promise) {
            pending.push(promise);
          });
  
        return Promise.all(pending);
      })().then(function (objects) {
        var node;
  
        // .isBone isn't in glTF spec. See ._markDefs
        if (nodeDef.isBone === true) {
          node = new Bone();
        } else if (objects.length > 1) {
          node = new Group();
        } else if (objects.length === 1) {
          node = objects[0];
        } else {
          node = new Object3D();
        }
  
        if (node !== objects[0]) {
          for (var i = 0, il = objects.length; i < il; i++) {
            node.add(objects[i]);
          }
        }
  
        if (nodeDef.name) {
          node.userData.name = nodeDef.name;
          node.name = nodeName;
        }
  
        assignExtrasToUserData(node, nodeDef);
  
        if (nodeDef.extensions)
          addUnknownExtensionsToUserData(extensions, node, nodeDef);
  
        if (nodeDef.matrix !== undefined) {
          var matrix = new Matrix4();
          matrix.fromArray(nodeDef.matrix);
          node.applyMatrix4(matrix);
        } else {
          if (nodeDef.translation !== undefined) {
            node.position.fromArray(nodeDef.translation);
          }
  
          if (nodeDef.rotation !== undefined) {
            node.quaternion.fromArray(nodeDef.rotation);
          }
  
          if (nodeDef.scale !== undefined) {
            node.scale.fromArray(nodeDef.scale);
          }
        }
  
        parser.associations.set(node, { type: "nodes", index: nodeIndex });
  
        return node;
      });
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
     * @param {number} sceneIndex
     * @return {Promise<Group>}
     */
    GLTFParser.prototype.loadScene = (function () {
      // scene node hierachy builder
  
      function buildNodeHierachy(nodeId, parentObject, json, parser) {
        var nodeDef = json.nodes[nodeId];
  
        return parser
          .getDependency("node", nodeId)
          .then(function (node) {
            if (nodeDef.skin === undefined) return node;
  
            // build skeleton here as well
  
            var skinEntry;
  
            return parser
              .getDependency("skin", nodeDef.skin)
              .then(function (skin) {
                skinEntry = skin;
  
                var pendingJoints = [];
  
                for (var i = 0, il = skinEntry.joints.length; i < il; i++) {
                  pendingJoints.push(
                    parser.getDependency("node", skinEntry.joints[i])
                  );
                }
  
                return Promise.all(pendingJoints);
              })
              .then(function (jointNodes) {
                node.traverse(function (mesh) {
                  if (!mesh.isMesh) return;
  
                  var bones = [];
                  var boneInverses = [];
  
                  for (var j = 0, jl = jointNodes.length; j < jl; j++) {
                    var jointNode = jointNodes[j];
  
                    if (jointNode) {
                      bones.push(jointNode);
  
                      var mat = new Matrix4();
  
                      if (skinEntry.inverseBindMatrices !== undefined) {
                        mat.fromArray(
                          skinEntry.inverseBindMatrices.array,
                          j * 16
                        );
                      }
  
                      boneInverses.push(mat);
                    } else {
                      console.warn(
                        'THREE.GLTFLoader: Joint "%s" could not be found.',
                        skinEntry.joints[j]
                      );
                    }
                  }
  
                  mesh.bind(new Skeleton(bones, boneInverses), mesh.matrixWorld);
                });
  
                return node;
              });
          })
          .then(function (node) {
            // build node hierachy
  
            parentObject.add(node);
  
            var pending = [];
  
            if (nodeDef.children) {
              var children = nodeDef.children;
  
              for (var i = 0, il = children.length; i < il; i++) {
                var child = children[i];
                pending.push(buildNodeHierachy(child, node, json, parser));
              }
            }
  
            return Promise.all(pending);
          });
      }
  
      return function loadScene(sceneIndex) {
        var json = this.json;
        var extensions = this.extensions;
        var sceneDef = this.json.scenes[sceneIndex];
        var parser = this;
  
        // Loader returns Group, not Scene.
        // See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172
        var scene = new Group();
        if (sceneDef.name) scene.name = parser.createUniqueName(sceneDef.name);
  
        assignExtrasToUserData(scene, sceneDef);
  
        if (sceneDef.extensions)
          addUnknownExtensionsToUserData(extensions, scene, sceneDef);
  
        var nodeIds = sceneDef.nodes || [];
  
        var pending = [];
  
        for (var i = 0, il = nodeIds.length; i < il; i++) {
          pending.push(buildNodeHierachy(nodeIds[i], scene, json, parser));
        }
  
        return Promise.all(pending).then(function () {
          return scene;
        });
      };
    })();
  
    return GLTFLoader;
  })();
  
  export { GLTFLoader };
  