ZhongMianAdmin/packages/kankan-sdk-deps/lib/loaders/GLTFLoader.js

;(function () {
    class GLTFLoader extends THREE.Loader {
        constructor(manager) {
            super(manager)
            this.dracoLoader = 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 GLTFMaterialsSheenExtension(parser)
            })
            this.register(function (parser) {
                return new GLTFMaterialsTransmissionExtension(parser)
            })
            this.register(function (parser) {
                return new GLTFMaterialsVolumeExtension(parser)
            })
            this.register(function (parser) {
                return new GLTFMaterialsIorExtension(parser)
            })
            this.register(function (parser) {
                return new GLTFMaterialsEmissiveStrengthExtension(parser)
            })
            this.register(function (parser) {
                return new GLTFMaterialsSpecularExtension(parser)
            })
            this.register(function (parser) {
                return new GLTFMaterialsIridescenceExtension(parser)
            })
            this.register(function (parser) {
                return new GLTFLightsExtension(parser)
            })
            this.register(function (parser) {
                return new GLTFMeshoptCompression(parser)
            })
        }

        load(url, onLoad, onProgress, onError) {
            const scope = this
            let resourcePath

            if (this.resourcePath !== '') {
                resourcePath = this.resourcePath
            } else if (this.path !== '') {
                resourcePath = this.path
            } else {
                resourcePath = THREE.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)

            const _onError = function (e) {
                if (onError) {
                    onError(e)
                } else {
                    console.error(e)
                }

                scope.manager.itemError(url)
                scope.manager.itemEnd(url)
            }

            const loader = new THREE.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(dracoLoader) {
            this.dracoLoader = dracoLoader
            return this
        }

        setDDSLoader() {
            throw new Error('THREE.GLTFLoader: "MSFT_texture_dds" no longer supported. Please update to "KHR_texture_basisu".')
        }

        setKTX2Loader(ktx2Loader) {
            this.ktx2Loader = ktx2Loader
            return this
        }

        setMeshoptDecoder(meshoptDecoder) {
            this.meshoptDecoder = meshoptDecoder
            return this
        }

        register(callback) {
            if (this.pluginCallbacks.indexOf(callback) === -1) {
                this.pluginCallbacks.push(callback)
            }

            return this
        }

        unregister(callback) {
            if (this.pluginCallbacks.indexOf(callback) !== -1) {
                this.pluginCallbacks.splice(this.pluginCallbacks.indexOf(callback), 1)
            }

            return this
        }

        parse(data, path, onLoad, onError) {
            let content
            const extensions = {}
            const plugins = {}

            if (typeof data === 'string') {
                content = data
            } else {
                const magic = THREE.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 = THREE.LoaderUtils.decodeText(new Uint8Array(data))
                }
            }

            const 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
            }

            const parser = new GLTFParser(json, {
                path: path || this.resourcePath || '',
                crossOrigin: this.crossOrigin,
                requestHeader: this.requestHeader,
                manager: this.manager,
                ktx2Loader: this.ktx2Loader,
                meshoptDecoder: this.meshoptDecoder,
            })
            parser.fileLoader.setRequestHeader(this.requestHeader)

            for (let i = 0; i < this.pluginCallbacks.length; i++) {
                const 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 (let i = 0; i < json.extensionsUsed.length; ++i) {
                    const extensionName = json.extensionsUsed[i]
                    const 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.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)
        }

        parseAsync(data, path) {
            const scope = this
            return new Promise(function (resolve, reject) {
                scope.parse(data, path, resolve, reject)
            })
        }
    }
    /* GLTFREGISTRY */

    function GLTFRegistry() {
        let 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 ***********/

    /*********************************/

    const 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_IOR: 'KHR_materials_ior',
        KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
        KHR_MATERIALS_SHEEN: 'KHR_materials_sheen',
        KHR_MATERIALS_SPECULAR: 'KHR_materials_specular',
        KHR_MATERIALS_TRANSMISSION: 'KHR_materials_transmission',
        KHR_MATERIALS_IRIDESCENCE: 'KHR_materials_iridescence',
        KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
        KHR_MATERIALS_VOLUME: 'KHR_materials_volume',
        KHR_TEXTURE_BASISU: 'KHR_texture_basisu',
        KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
        KHR_MESH_QUANTIZATION: 'KHR_mesh_quantization',
        KHR_MATERIALS_EMISSIVE_STRENGTH: 'KHR_materials_emissive_strength',
        EXT_TEXTURE_WEBP: 'EXT_texture_webp',
        EXT_MESHOPT_COMPRESSION: 'EXT_meshopt_compression',
    }
    /**
     * Punctual Lights Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
     */

    class GLTFLightsExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL // THREE.Object3D instance caches

            this.cache = {
                refs: {},
                uses: {},
            }
        }

        _markDefs() {
            const parser = this.parser
            const nodeDefs = this.parser.json.nodes || []

            for (let nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex++) {
                const 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)
                }
            }
        }

        _loadLight(lightIndex) {
            const parser = this.parser
            const cacheKey = 'light:' + lightIndex
            let dependency = parser.cache.get(cacheKey)
            if (dependency) return dependency
            const json = parser.json
            const extensions = (json.extensions && json.extensions[this.name]) || {}
            const lightDefs = extensions.lights || []
            const lightDef = lightDefs[lightIndex]
            let lightNode
            const color = new THREE.Color(0xffffff)
            if (lightDef.color !== undefined) color.fromArray(lightDef.color)
            const range = lightDef.range !== undefined ? lightDef.range : 0

            switch (lightDef.type) {
                case 'directional':
                    lightNode = new THREE.DirectionalLight(color)
                    lightNode.target.position.set(0, 0, -1)
                    lightNode.add(lightNode.target)
                    break

                case 'point':
                    lightNode = new THREE.PointLight(color)
                    lightNode.distance = range
                    break

                case 'spot':
                    lightNode = new THREE.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
        }

        createNodeAttachment(nodeIndex) {
            const self = this
            const parser = this.parser
            const json = parser.json
            const nodeDef = json.nodes[nodeIndex]
            const lightDef = (nodeDef.extensions && nodeDef.extensions[this.name]) || {}
            const 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
     */

    class GLTFMaterialsUnlitExtension {
        constructor() {
            this.name = EXTENSIONS.KHR_MATERIALS_UNLIT
        }

        getMaterialType() {
            return THREE.MeshBasicMaterial
        }

        extendParams(materialParams, materialDef, parser) {
            const pending = []
            materialParams.color = new THREE.Color(1.0, 1.0, 1.0)
            materialParams.opacity = 1.0
            const metallicRoughness = materialDef.pbrMetallicRoughness

            if (metallicRoughness) {
                if (Array.isArray(metallicRoughness.baseColorFactor)) {
                    const array = metallicRoughness.baseColorFactor
                    materialParams.color.fromArray(array)
                    materialParams.opacity = array[3]
                }

                if (metallicRoughness.baseColorTexture !== undefined) {
                    pending.push(parser.assignTexture(materialParams, 'map', metallicRoughness.baseColorTexture, THREE.sRGBEncoding))
                }
            }

            return Promise.all(pending)
        }
    }
    /**
     * Materials Emissive Strength Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/blob/5768b3ce0ef32bc39cdf1bef10b948586635ead3/extensions/2.0/Khronos/KHR_materials_emissive_strength/README.md
     */

    class GLTFMaterialsEmissiveStrengthExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_MATERIALS_EMISSIVE_STRENGTH
        }

        extendMaterialParams(materialIndex, materialParams) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]

            if (!materialDef.extensions || !materialDef.extensions[this.name]) {
                return Promise.resolve()
            }

            const emissiveStrength = materialDef.extensions[this.name].emissiveStrength

            if (emissiveStrength !== undefined) {
                materialParams.emissiveIntensity = emissiveStrength
            }

            return Promise.resolve()
        }
    }
    /**
     * Clearcoat Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
     */

    class GLTFMaterialsClearcoatExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT
        }

        getMaterialType(materialIndex) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]
            if (!materialDef.extensions || !materialDef.extensions[this.name]) return null
            return THREE.MeshPhysicalMaterial
        }

        extendMaterialParams(materialIndex, materialParams) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]

            if (!materialDef.extensions || !materialDef.extensions[this.name]) {
                return Promise.resolve()
            }

            const pending = []
            const 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) {
                    const scale = extension.clearcoatNormalTexture.scale
                    materialParams.clearcoatNormalScale = new THREE.Vector2(scale, scale)
                }
            }

            return Promise.all(pending)
        }
    }
    /**
     * Iridescence Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_iridescence
     */

    class GLTFMaterialsIridescenceExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_MATERIALS_IRIDESCENCE
        }

        getMaterialType(materialIndex) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]
            if (!materialDef.extensions || !materialDef.extensions[this.name]) return null
            return THREE.MeshPhysicalMaterial
        }

        extendMaterialParams(materialIndex, materialParams) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]

            if (!materialDef.extensions || !materialDef.extensions[this.name]) {
                return Promise.resolve()
            }

            const pending = []
            const extension = materialDef.extensions[this.name]

            if (extension.iridescenceFactor !== undefined) {
                materialParams.iridescence = extension.iridescenceFactor
            }

            if (extension.iridescenceTexture !== undefined) {
                pending.push(parser.assignTexture(materialParams, 'iridescenceMap', extension.iridescenceTexture))
            }

            if (extension.iridescenceIor !== undefined) {
                materialParams.iridescenceIOR = extension.iridescenceIor
            }

            if (materialParams.iridescenceThicknessRange === undefined) {
                materialParams.iridescenceThicknessRange = [100, 400]
            }

            if (extension.iridescenceThicknessMinimum !== undefined) {
                materialParams.iridescenceThicknessRange[0] = extension.iridescenceThicknessMinimum
            }

            if (extension.iridescenceThicknessMaximum !== undefined) {
                materialParams.iridescenceThicknessRange[1] = extension.iridescenceThicknessMaximum
            }

            if (extension.iridescenceThicknessTexture !== undefined) {
                pending.push(parser.assignTexture(materialParams, 'iridescenceThicknessMap', extension.iridescenceThicknessTexture))
            }

            return Promise.all(pending)
        }
    }
    /**
     * Sheen Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_sheen
     */

    class GLTFMaterialsSheenExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_MATERIALS_SHEEN
        }

        getMaterialType(materialIndex) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]
            if (!materialDef.extensions || !materialDef.extensions[this.name]) return null
            return THREE.MeshPhysicalMaterial
        }

        extendMaterialParams(materialIndex, materialParams) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]

            if (!materialDef.extensions || !materialDef.extensions[this.name]) {
                return Promise.resolve()
            }

            const pending = []
            materialParams.sheenColor = new THREE.Color(0, 0, 0)
            materialParams.sheenRoughness = 0
            materialParams.sheen = 1
            const extension = materialDef.extensions[this.name]

            if (extension.sheenColorFactor !== undefined) {
                materialParams.sheenColor.fromArray(extension.sheenColorFactor)
            }

            if (extension.sheenRoughnessFactor !== undefined) {
                materialParams.sheenRoughness = extension.sheenRoughnessFactor
            }

            if (extension.sheenColorTexture !== undefined) {
                pending.push(parser.assignTexture(materialParams, 'sheenColorMap', extension.sheenColorTexture, THREE.sRGBEncoding))
            }

            if (extension.sheenRoughnessTexture !== undefined) {
                pending.push(parser.assignTexture(materialParams, 'sheenRoughnessMap', extension.sheenRoughnessTexture))
            }

            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
     */

    class GLTFMaterialsTransmissionExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_MATERIALS_TRANSMISSION
        }

        getMaterialType(materialIndex) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]
            if (!materialDef.extensions || !materialDef.extensions[this.name]) return null
            return THREE.MeshPhysicalMaterial
        }

        extendMaterialParams(materialIndex, materialParams) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]

            if (!materialDef.extensions || !materialDef.extensions[this.name]) {
                return Promise.resolve()
            }

            const pending = []
            const 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)
        }
    }
    /**
     * Materials Volume Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_volume
     */

    class GLTFMaterialsVolumeExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_MATERIALS_VOLUME
        }

        getMaterialType(materialIndex) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]
            if (!materialDef.extensions || !materialDef.extensions[this.name]) return null
            return THREE.MeshPhysicalMaterial
        }

        extendMaterialParams(materialIndex, materialParams) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]

            if (!materialDef.extensions || !materialDef.extensions[this.name]) {
                return Promise.resolve()
            }

            const pending = []
            const extension = materialDef.extensions[this.name]
            materialParams.thickness = extension.thicknessFactor !== undefined ? extension.thicknessFactor : 0

            if (extension.thicknessTexture !== undefined) {
                pending.push(parser.assignTexture(materialParams, 'thicknessMap', extension.thicknessTexture))
            }

            materialParams.attenuationDistance = extension.attenuationDistance || 0
            const colorArray = extension.attenuationColor || [1, 1, 1]
            materialParams.attenuationColor = new THREE.Color(colorArray[0], colorArray[1], colorArray[2])
            return Promise.all(pending)
        }
    }
    /**
     * Materials ior Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_ior
     */

    class GLTFMaterialsIorExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_MATERIALS_IOR
        }

        getMaterialType(materialIndex) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]
            if (!materialDef.extensions || !materialDef.extensions[this.name]) return null
            return THREE.MeshPhysicalMaterial
        }

        extendMaterialParams(materialIndex, materialParams) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]

            if (!materialDef.extensions || !materialDef.extensions[this.name]) {
                return Promise.resolve()
            }

            const extension = materialDef.extensions[this.name]
            materialParams.ior = extension.ior !== undefined ? extension.ior : 1.5
            return Promise.resolve()
        }
    }
    /**
     * Materials specular Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_specular
     */

    class GLTFMaterialsSpecularExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_MATERIALS_SPECULAR
        }

        getMaterialType(materialIndex) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]
            if (!materialDef.extensions || !materialDef.extensions[this.name]) return null
            return THREE.MeshPhysicalMaterial
        }

        extendMaterialParams(materialIndex, materialParams) {
            const parser = this.parser
            const materialDef = parser.json.materials[materialIndex]

            if (!materialDef.extensions || !materialDef.extensions[this.name]) {
                return Promise.resolve()
            }

            const pending = []
            const extension = materialDef.extensions[this.name]
            materialParams.specularIntensity = extension.specularFactor !== undefined ? extension.specularFactor : 1.0

            if (extension.specularTexture !== undefined) {
                pending.push(parser.assignTexture(materialParams, 'specularIntensityMap', extension.specularTexture))
            }

            const colorArray = extension.specularColorFactor || [1, 1, 1]
            materialParams.specularColor = new THREE.Color(colorArray[0], colorArray[1], colorArray[2])

            if (extension.specularColorTexture !== undefined) {
                pending.push(parser.assignTexture(materialParams, 'specularColorMap', extension.specularColorTexture, THREE.sRGBEncoding))
            }

            return Promise.all(pending)
        }
    }
    /**
     * BasisU THREE.Texture Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu
     */

    class GLTFTextureBasisUExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.KHR_TEXTURE_BASISU
        }

        loadTexture(textureIndex) {
            const parser = this.parser
            const json = parser.json
            const textureDef = json.textures[textureIndex]

            if (!textureDef.extensions || !textureDef.extensions[this.name]) {
                return null
            }

            const extension = textureDef.extensions[this.name]
            const 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, extension.source, loader)
        }
    }
    /**
     * WebP THREE.Texture Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_texture_webp
     */

    class GLTFTextureWebPExtension {
        constructor(parser) {
            this.parser = parser
            this.name = EXTENSIONS.EXT_TEXTURE_WEBP
            this.isSupported = null
        }

        loadTexture(textureIndex) {
            const name = this.name
            const parser = this.parser
            const json = parser.json
            const textureDef = json.textures[textureIndex]

            if (!textureDef.extensions || !textureDef.extensions[name]) {
                return null
            }

            const extension = textureDef.extensions[name]
            const source = json.images[extension.source]
            let loader = parser.textureLoader

            if (source.uri) {
                const handler = parser.options.manager.getHandler(source.uri)
                if (handler !== null) loader = handler
            }

            return this.detectSupport().then(function (isSupported) {
                if (isSupported) return parser.loadTextureImage(textureIndex, extension.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)
            })
        }

        detectSupport() {
            if (!this.isSupported) {
                this.isSupported = new Promise(function (resolve) {
                    const 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
     */

    class GLTFMeshoptCompression {
        constructor(parser) {
            this.name = EXTENSIONS.EXT_MESHOPT_COMPRESSION
            this.parser = parser
        }

        loadBufferView(index) {
            const json = this.parser.json
            const bufferView = json.bufferViews[index]

            if (bufferView.extensions && bufferView.extensions[this.name]) {
                const extensionDef = bufferView.extensions[this.name]
                const buffer = this.parser.getDependency('buffer', extensionDef.buffer)
                const 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 buffer.then(function (res) {
                    const byteOffset = extensionDef.byteOffset || 0
                    const byteLength = extensionDef.byteLength || 0
                    const count = extensionDef.count
                    const stride = extensionDef.byteStride
                    const source = new Uint8Array(res, byteOffset, byteLength)

                    if (decoder.decodeGltfBufferAsync) {
                        return decoder.decodeGltfBufferAsync(count, stride, source, extensionDef.mode, extensionDef.filter).then(function (res) {
                            return res.buffer
                        })
                    } else {
                        // Support for MeshoptDecoder 0.18 or earlier, without decodeGltfBufferAsync
                        return decoder.ready.then(function () {
                            const result = new ArrayBuffer(count * stride)
                            decoder.decodeGltfBuffer(new Uint8Array(result), count, stride, source, extensionDef.mode, extensionDef.filter)
                            return result
                        })
                    }
                })
            } else {
                return null
            }
        }
    }
    /* BINARY EXTENSION */

    const BINARY_EXTENSION_HEADER_MAGIC = 'glTF'
    const BINARY_EXTENSION_HEADER_LENGTH = 12
    const BINARY_EXTENSION_CHUNK_TYPES = {
        JSON: 0x4e4f534a,
        BIN: 0x004e4942,
    }

    class GLTFBinaryExtension {
        constructor(data) {
            this.name = EXTENSIONS.KHR_BINARY_GLTF
            this.content = null
            this.body = null
            const headerView = new DataView(data, 0, BINARY_EXTENSION_HEADER_LENGTH)
            this.header = {
                magic: THREE.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.')
            }

            const chunkContentsLength = this.header.length - BINARY_EXTENSION_HEADER_LENGTH
            const chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH)
            let chunkIndex = 0

            while (chunkIndex < chunkContentsLength) {
                const chunkLength = chunkView.getUint32(chunkIndex, true)
                chunkIndex += 4
                const chunkType = chunkView.getUint32(chunkIndex, true)
                chunkIndex += 4

                if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {
                    const contentArray = new Uint8Array(data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength)
                    this.content = THREE.LoaderUtils.decodeText(contentArray)
                } else if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN) {
                    const 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 THREE.Mesh Compression Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
     */

    class GLTFDracoMeshCompressionExtension {
        constructor(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()
        }

        decodePrimitive(primitive, parser) {
            const json = this.json
            const dracoLoader = this.dracoLoader
            const bufferViewIndex = primitive.extensions[this.name].bufferView
            const gltfAttributeMap = primitive.extensions[this.name].attributes
            const threeAttributeMap = {}
            const attributeNormalizedMap = {}
            const attributeTypeMap = {}

            for (const attributeName in gltfAttributeMap) {
                const threeAttributeName = ATTRIBUTES[attributeName] || attributeName.toLowerCase()
                threeAttributeMap[threeAttributeName] = gltfAttributeMap[attributeName]
            }

            for (const attributeName in primitive.attributes) {
                const threeAttributeName = ATTRIBUTES[attributeName] || attributeName.toLowerCase()

                if (gltfAttributeMap[attributeName] !== undefined) {
                    const accessorDef = json.accessors[primitive.attributes[attributeName]]
                    const componentType = WEBGL_COMPONENT_TYPES[accessorDef.componentType]
                    attributeTypeMap[threeAttributeName] = componentType.name
                    attributeNormalizedMap[threeAttributeName] = accessorDef.normalized === true
                }
            }

            return parser.getDependency('bufferView', bufferViewIndex).then(function (bufferView) {
                return new Promise(function (resolve) {
                    dracoLoader.decodeDracoFile(
                        bufferView,
                        function (geometry) {
                            for (const attributeName in geometry.attributes) {
                                const attribute = geometry.attributes[attributeName]
                                const normalized = attributeNormalizedMap[attributeName]
                                if (normalized !== undefined) attribute.normalized = normalized
                            }

                            resolve(geometry)
                        },
                        threeAttributeMap,
                        attributeTypeMap
                    )
                })
            })
        }
    }
    /**
     * THREE.Texture Transform Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
     */

    class GLTFTextureTransformExtension {
        constructor() {
            this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM
        }

        extendTexture(texture, transform) {
            if (transform.texCoord !== undefined) {
                console.warn('THREE.GLTFLoader: Custom UV sets in "' + this.name + '" extension not yet supported.')
            }

            if (transform.offset === undefined && transform.rotation === undefined && transform.scale === undefined) {
                // See https://github.com/mrdoob/three.js/issues/21819.
                return texture
            }

            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)
            }

            texture.needsUpdate = true
            return texture
        }
    }
    /**
     * Specular-Glossiness Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Archived/KHR_materials_pbrSpecularGlossiness
     */

    /**
     * A sub class of StandardMaterial with some of the functionality
     * changed via the `onBeforeCompile` callback
     * @pailhead
     */

    class GLTFMeshStandardSGMaterial extends THREE.MeshStandardMaterial {
        constructor(params) {
            super()
            this.isGLTFSpecularGlossinessMaterial = true //various chunks that need replacing

            const specularMapParsFragmentChunk = ['#ifdef USE_SPECULARMAP', '	uniform sampler2D specularMap;', '#endif'].join('\n')
            const glossinessMapParsFragmentChunk = ['#ifdef USE_GLOSSINESSMAP', '	uniform sampler2D glossinessMap;', '#endif'].join('\n')
            const specularMapFragmentChunk = [
                'vec3 specularFactor = specular;',
                '#ifdef USE_SPECULARMAP',
                '	vec4 texelSpecular = texture2D( specularMap, vUv );',
                '	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture',
                '	specularFactor *= texelSpecular.rgb;',
                '#endif',
            ].join('\n')
            const 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')
            const 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.roughness = max( 1.0 - glossinessFactor, 0.0525 ); // 0.0525 corresponds to the base mip of a 256 cubemap.',
                'material.roughness += geometryRoughness;',
                'material.roughness = min( material.roughness, 1.0 );',
                'material.specularColor = specularFactor;',
            ].join('\n')
            const uniforms = {
                specular: {
                    value: new THREE.Color().setHex(0xffffff),
                },
                glossiness: {
                    value: 1,
                },
                specularMap: {
                    value: null,
                },
                glossinessMap: {
                    value: null,
                },
            }
            this._extraUniforms = uniforms

            this.onBeforeCompile = function (shader) {
                for (const 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)
        }

        copy(source) {
            super.copy(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
        }
    }

    class GLTFMaterialsPbrSpecularGlossinessExtension {
        constructor() {
            this.name = EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS
            this.specularGlossinessParams = [
                'color',
                'map',
                'lightMap',
                'lightMapIntensity',
                'aoMap',
                'aoMapIntensity',
                'emissive',
                'emissiveIntensity',
                'emissiveMap',
                'bumpMap',
                'bumpScale',
                'normalMap',
                'normalMapType',
                'displacementMap',
                'displacementScale',
                'displacementBias',
                'specularMap',
                'specular',
                'glossinessMap',
                'glossiness',
                'alphaMap',
                'envMap',
                'envMapIntensity',
            ]
        }

        getMaterialType() {
            return GLTFMeshStandardSGMaterial
        }

        extendParams(materialParams, materialDef, parser) {
            const pbrSpecularGlossiness = materialDef.extensions[this.name]
            materialParams.color = new THREE.Color(1.0, 1.0, 1.0)
            materialParams.opacity = 1.0
            const pending = []

            if (Array.isArray(pbrSpecularGlossiness.diffuseFactor)) {
                const array = pbrSpecularGlossiness.diffuseFactor
                materialParams.color.fromArray(array)
                materialParams.opacity = array[3]
            }

            if (pbrSpecularGlossiness.diffuseTexture !== undefined) {
                pending.push(parser.assignTexture(materialParams, 'map', pbrSpecularGlossiness.diffuseTexture, THREE.sRGBEncoding))
            }

            materialParams.emissive = new THREE.Color(0.0, 0.0, 0.0)
            materialParams.glossiness = pbrSpecularGlossiness.glossinessFactor !== undefined ? pbrSpecularGlossiness.glossinessFactor : 1.0
            materialParams.specular = new THREE.Color(1.0, 1.0, 1.0)

            if (Array.isArray(pbrSpecularGlossiness.specularFactor)) {
                materialParams.specular.fromArray(pbrSpecularGlossiness.specularFactor)
            }

            if (pbrSpecularGlossiness.specularGlossinessTexture !== undefined) {
                const specGlossMapDef = pbrSpecularGlossiness.specularGlossinessTexture
                pending.push(parser.assignTexture(materialParams, 'glossinessMap', specGlossMapDef))
                pending.push(parser.assignTexture(materialParams, 'specularMap', specGlossMapDef, THREE.sRGBEncoding))
            }

            return Promise.all(pending)
        }

        createMaterial(materialParams) {
            const 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 = materialParams.emissiveIntensity === undefined ? 1.0 : materialParams.emissiveIntensity
            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 = THREE.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
            return material
        }
    }
    /**
     * THREE.Mesh Quantization Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
     */

    class GLTFMeshQuantizationExtension {
        constructor() {
            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

    class GLTFCubicSplineInterpolant extends THREE.Interpolant {
        constructor(parameterPositions, sampleValues, sampleSize, resultBuffer) {
            super(parameterPositions, sampleValues, sampleSize, resultBuffer)
        }

        copySampleValue_(index) {
            // Copies a sample value to the result buffer. See description of glTF
            // CUBICSPLINE values layout in interpolate_() function below.
            const result = this.resultBuffer,
                values = this.sampleValues,
                valueSize = this.valueSize,
                offset = index * valueSize * 3 + valueSize

            for (let i = 0; i !== valueSize; i++) {
                result[i] = values[offset + i]
            }

            return result
        }

        interpolate_(i1, t0, t, t1) {
            const result = this.resultBuffer
            const values = this.sampleValues
            const stride = this.valueSize
            const stride2 = stride * 2
            const stride3 = stride * 3
            const td = t1 - t0
            const p = (t - t0) / td
            const pp = p * p
            const ppp = pp * p
            const offset1 = i1 * stride3
            const offset0 = offset1 - stride3
            const s2 = -2 * ppp + 3 * pp
            const s3 = ppp - pp
            const s0 = 1 - s2
            const s1 = s3 - pp + p // Layout of keyframe output values for CUBICSPLINE animations:
            //   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]

            for (let i = 0; i !== stride; i++) {
                const p0 = values[offset0 + i + stride] // splineVertex_k

                const m0 = values[offset0 + i + stride2] * td // outTangent_k * (t_k+1 - t_k)

                const p1 = values[offset1 + i + stride] // splineVertex_k+1

                const 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
        }
    }

    const _q = new THREE.Quaternion()

    class GLTFCubicSplineQuaternionInterpolant extends GLTFCubicSplineInterpolant {
        interpolate_(i1, t0, t, t1) {
            const result = super.interpolate_(i1, t0, t, t1)

            _q.fromArray(result).normalize().toArray(result)

            return result
        }
    }
    /*********************************/

    /********** INTERNALS ************/

    /*********************************/

    /* CONSTANTS */

    const 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,
    }
    const WEBGL_COMPONENT_TYPES = {
        5120: Int8Array,
        5121: Uint8Array,
        5122: Int16Array,
        5123: Uint16Array,
        5125: Uint32Array,
        5126: Float32Array,
    }
    const WEBGL_FILTERS = {
        9728: THREE.NearestFilter,
        9729: THREE.LinearFilter,
        9984: THREE.NearestMipmapNearestFilter,
        9985: THREE.LinearMipmapNearestFilter,
        9986: THREE.NearestMipmapLinearFilter,
        9987: THREE.LinearMipmapLinearFilter,
    }
    const WEBGL_WRAPPINGS = {
        33071: THREE.ClampToEdgeWrapping,
        33648: THREE.MirroredRepeatWrapping,
        10497: THREE.RepeatWrapping,
    }
    const WEBGL_TYPE_SIZES = {
        SCALAR: 1,
        VEC2: 2,
        VEC3: 3,
        VEC4: 4,
        MAT2: 4,
        MAT3: 9,
        MAT4: 16,
    }
    const ATTRIBUTES = {
        POSITION: 'position',
        NORMAL: 'normal',
        TANGENT: 'tangent',
        TEXCOORD_0: 'uv',
        TEXCOORD_1: 'uv2',
        COLOR_0: 'color',
        WEIGHTS_0: 'skinWeight',
        JOINTS_0: 'skinIndex',
    }
    const PATH_PROPERTIES = {
        scale: 'scale',
        translation: 'position',
        rotation: 'quaternion',
        weights: 'morphTargetInfluences',
    }
    const 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: THREE.InterpolateLinear,
        STEP: THREE.InterpolateDiscrete,
    }
    const ALPHA_MODES = {
        OPAQUE: 'OPAQUE',
        MASK: 'MASK',
        BLEND: 'BLEND',
    }
    /**
     * 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 THREE.MeshStandardMaterial({
                color: 0xffffff,
                emissive: 0x000000,
                metalness: 1,
                roughness: 1,
                transparent: false,
                depthTest: true,
                side: THREE.FrontSide,
            })
        }

        return cache['DefaultMaterial']
    }

    function addUnknownExtensionsToUserData(knownExtensions, object, objectDef) {
        // Add unknown glTF extensions to an object's userData.
        for (const 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) {
        let hasMorphPosition = false
        let hasMorphNormal = false
        let hasMorphColor = false

        for (let i = 0, il = targets.length; i < il; i++) {
            const target = targets[i]
            if (target.POSITION !== undefined) hasMorphPosition = true
            if (target.NORMAL !== undefined) hasMorphNormal = true
            if (target.COLOR_0 !== undefined) hasMorphColor = true
            if (hasMorphPosition && hasMorphNormal && hasMorphColor) break
        }

        if (!hasMorphPosition && !hasMorphNormal && !hasMorphColor) return Promise.resolve(geometry)
        const pendingPositionAccessors = []
        const pendingNormalAccessors = []
        const pendingColorAccessors = []

        for (let i = 0, il = targets.length; i < il; i++) {
            const target = targets[i]

            if (hasMorphPosition) {
                const pendingAccessor = target.POSITION !== undefined ? parser.getDependency('accessor', target.POSITION) : geometry.attributes.position
                pendingPositionAccessors.push(pendingAccessor)
            }

            if (hasMorphNormal) {
                const pendingAccessor = target.NORMAL !== undefined ? parser.getDependency('accessor', target.NORMAL) : geometry.attributes.normal
                pendingNormalAccessors.push(pendingAccessor)
            }

            if (hasMorphColor) {
                const pendingAccessor = target.COLOR_0 !== undefined ? parser.getDependency('accessor', target.COLOR_0) : geometry.attributes.color
                pendingColorAccessors.push(pendingAccessor)
            }
        }

        return Promise.all([Promise.all(pendingPositionAccessors), Promise.all(pendingNormalAccessors), Promise.all(pendingColorAccessors)]).then(function (accessors) {
            const morphPositions = accessors[0]
            const morphNormals = accessors[1]
            const morphColors = accessors[2]
            if (hasMorphPosition) geometry.morphAttributes.position = morphPositions
            if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals
            if (hasMorphColor) geometry.morphAttributes.color = morphColors
            geometry.morphTargetsRelative = true
            return geometry
        })
    }
    /**
     * @param {Mesh} mesh
     * @param {GLTF.Mesh} meshDef
     */

    function updateMorphTargets(mesh, meshDef) {
        mesh.updateMorphTargets()

        if (meshDef.weights !== undefined) {
            for (let 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)) {
            const targetNames = meshDef.extras.targetNames

            if (mesh.morphTargetInfluences.length === targetNames.length) {
                mesh.morphTargetDictionary = {}

                for (let 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) {
        const dracoExtension = primitiveDef.extensions && primitiveDef.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
        let 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) {
        let attributesKey = ''
        const keys = Object.keys(attributes).sort()

        for (let i = 0, il = keys.length; i < il; i++) {
            attributesKey += keys[i] + ':' + attributes[keys[i]] + ';'
        }

        return attributesKey
    }

    function getNormalizedComponentScale(constructor) {
        // Reference:
        // https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization#encoding-quantized-data
        switch (constructor) {
            case Int8Array:
                return 1 / 127

            case Uint8Array:
                return 1 / 255

            case Int16Array:
                return 1 / 32767

            case Uint16Array:
                return 1 / 65535

            default:
                throw new Error('THREE.GLTFLoader: Unsupported normalized accessor component type.')
        }
    }

    function getImageURIMimeType(uri) {
        if (uri.search(/\.jpe?g($|\?)/i) > 0 || uri.search(/^data\:image\/jpeg/) === 0) return 'image/jpeg'
        if (uri.search(/\.webp($|\?)/i) > 0 || uri.search(/^data\:image\/webp/) === 0) return 'image/webp'
        return 'image/png'
    }
    /* GLTF PARSER */

    class GLTFParser {
        constructor(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() // THREE.BufferGeometry caching

            this.primitiveCache = {} // THREE.Object3D instance caches

            this.meshCache = {
                refs: {},
                uses: {},
            }
            this.cameraCache = {
                refs: {},
                uses: {},
            }
            this.lightCache = {
                refs: {},
                uses: {},
            }
            this.sourceCache = {}
            this.textureCache = {} // Track node names, to ensure no duplicates

            this.nodeNamesUsed = {} // Use an THREE.ImageBitmapLoader if imageBitmaps are supported. Moves much of the
            // expensive work of uploading a texture to the GPU off the main thread.

            const isSafari = /^((?!chrome|android).)*safari/i.test(navigator.userAgent) === true
            const isFirefox = navigator.userAgent.indexOf('Firefox') > -1
            const firefoxVersion = isFirefox ? navigator.userAgent.match(/Firefox\/([0-9]+)\./)[1] : -1

            if (typeof createImageBitmap === 'undefined' || isSafari || (isFirefox && firefoxVersion < 98)) {
                this.textureLoader = new THREE.TextureLoader(this.options.manager)
            } else {
                this.textureLoader = new THREE.ImageBitmapLoader(this.options.manager)
            }

            this.textureLoader.setCrossOrigin(this.options.crossOrigin)
            this.textureLoader.setRequestHeader(this.options.requestHeader)
            this.fileLoader = new THREE.FileLoader(this.options.manager)
            this.fileLoader.setResponseType('arraybuffer')

            if (this.options.crossOrigin === 'use-credentials') {
                this.fileLoader.setWithCredentials(true)
            }
        }

        setExtensions(extensions) {
            this.extensions = extensions
        }

        setPlugins(plugins) {
            this.plugins = plugins
        }

        parse(onLoad, onError) {
            const parser = this
            const json = this.json
            const 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._invokeAll(function (ext) {
                    return ext.beforeRoot && ext.beforeRoot()
                })
            )
                .then(function () {
                    return Promise.all([parser.getDependencies('scene'), parser.getDependencies('animation'), parser.getDependencies('camera')])
                })
                .then(function (dependencies) {
                    const 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)
                    Promise.all(
                        parser._invokeAll(function (ext) {
                            return ext.afterRoot && ext.afterRoot(result)
                        })
                    ).then(function () {
                        onLoad(result)
                    })
                })
                .catch(onError)
        }
        /**
         * Marks the special nodes/meshes in json for efficient parse.
         */

        _markDefs() {
            const nodeDefs = this.json.nodes || []
            const skinDefs = this.json.skins || []
            const meshDefs = this.json.meshes || [] // Nothing in the node definition indicates whether it is a THREE.Bone or an
            // THREE.Object3D. Use the skins' joint references to mark bones.

            for (let skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex++) {
                const joints = skinDefs[skinIndex].joints

                for (let 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 (let nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex++) {
                const nodeDef = nodeDefs[nodeIndex]

                if (nodeDef.mesh !== undefined) {
                    this._addNodeRef(this.meshCache, nodeDef.mesh) // Nothing in the mesh definition indicates whether it is
                    // a THREE.SkinnedMesh or THREE.Mesh. Use the node's mesh reference
                    // to mark THREE.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 / THREE.Object3D resources. These resources
         * can be reused, or "instantiated", at multiple nodes in the scene
         * hierarchy. THREE.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.
         */

        _addNodeRef(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. */

        _getNodeRef(cache, index, object) {
            if (cache.refs[index] <= 1) return object
            const ref = object.clone() // Propagates mappings to the cloned object, prevents mappings on the
            // original object from being lost.

            const updateMappings = (original, clone) => {
                const mappings = this.associations.get(original)

                if (mappings != null) {
                    this.associations.set(clone, mappings)
                }

                for (const [i, child] of original.children.entries()) {
                    updateMappings(child, clone.children[i])
                }
            }

            updateMappings(object, ref)
            ref.name += '_instance_' + cache.uses[index]++
            return ref
        }

        _invokeOne(func) {
            const extensions = Object.values(this.plugins)
            extensions.push(this)

            for (let i = 0; i < extensions.length; i++) {
                const result = func(extensions[i])
                if (result) return result
            }

            return null
        }

        _invokeAll(func) {
            const extensions = Object.values(this.plugins)
            extensions.unshift(this)
            const pending = []

            for (let i = 0; i < extensions.length; i++) {
                const 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>}
         */

        getDependency(type, index) {
            const cacheKey = type + ':' + index
            let 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._invokeOne(function (ext) {
                            return ext.loadAnimation && ext.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>>}
         */

        getDependencies(type) {
            let dependencies = this.cache.get(type)

            if (!dependencies) {
                const parser = this
                const 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>}
         */

        loadBuffer(bufferIndex) {
            const bufferDef = this.json.buffers[bufferIndex]
            const 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)
            }

            const options = this.options
            return new Promise(function (resolve, reject) {
                loader.load(THREE.LoaderUtils.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>}
         */

        loadBufferView(bufferViewIndex) {
            const bufferViewDef = this.json.bufferViews[bufferViewIndex]
            return this.getDependency('buffer', bufferViewDef.buffer).then(function (buffer) {
                const byteLength = bufferViewDef.byteLength || 0
                const 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>}
         */

        loadAccessor(accessorIndex) {
            const parser = this
            const json = this.json
            const 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)
            }

            const 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) {
                const bufferView = bufferViews[0]
                const itemSize = WEBGL_TYPE_SIZES[accessorDef.type]
                const TypedArray = WEBGL_COMPONENT_TYPES[accessorDef.componentType] // For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.

                const elementBytes = TypedArray.BYTES_PER_ELEMENT
                const itemBytes = elementBytes * itemSize
                const byteOffset = accessorDef.byteOffset || 0
                const byteStride = accessorDef.bufferView !== undefined ? json.bufferViews[accessorDef.bufferView].byteStride : undefined
                const normalized = accessorDef.normalized === true
                let 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 THREE.InterleavedBuffer
                    // This makes sure that IBA.count reflects accessor.count properly
                    const ibSlice = Math.floor(byteOffset / byteStride)
                    const ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType + ':' + ibSlice + ':' + accessorDef.count
                    let 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 THREE.InterleavedBuffer(array, byteStride / elementBytes)
                        parser.cache.add(ibCacheKey, ib)
                    }

                    bufferAttribute = new THREE.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 THREE.BufferAttribute(array, itemSize, normalized)
                } // https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors

                if (accessorDef.sparse !== undefined) {
                    const itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR
                    const TypedArrayIndices = WEBGL_COMPONENT_TYPES[accessorDef.sparse.indices.componentType]
                    const byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0
                    const byteOffsetValues = accessorDef.sparse.values.byteOffset || 0
                    const sparseIndices = new TypedArrayIndices(bufferViews[1], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices)
                    const 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 THREE.BufferAttribute(bufferAttribute.array.slice(), bufferAttribute.itemSize, bufferAttribute.normalized)
                    }

                    for (let i = 0, il = sparseIndices.length; i < il; i++) {
                        const 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 THREE.BufferAttribute.')
                    }
                }

                return bufferAttribute
            })
        }
        /**
         * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
         * @param {number} textureIndex
         * @return {Promise<THREE.Texture>}
         */

        loadTexture(textureIndex) {
            const json = this.json
            const options = this.options
            const textureDef = json.textures[textureIndex]
            const sourceIndex = textureDef.source
            const sourceDef = json.images[sourceIndex]
            let loader = this.textureLoader

            if (sourceDef.uri) {
                const handler = options.manager.getHandler(sourceDef.uri)
                if (handler !== null) loader = handler
            }

            return this.loadTextureImage(textureIndex, sourceIndex, loader)
        }

        loadTextureImage(textureIndex, sourceIndex, loader) {
            const parser = this
            const json = this.json
            const textureDef = json.textures[textureIndex]
            const sourceDef = json.images[sourceIndex]
            const cacheKey = (sourceDef.uri || sourceDef.bufferView) + ':' + textureDef.sampler

            if (this.textureCache[cacheKey]) {
                // See https://github.com/mrdoob/three.js/issues/21559.
                return this.textureCache[cacheKey]
            }

            const promise = this.loadImageSource(sourceIndex, loader)
                .then(function (texture) {
                    texture.flipY = false
                    if (textureDef.name) texture.name = textureDef.name
                    const samplers = json.samplers || {}
                    const sampler = samplers[textureDef.sampler] || {}
                    texture.magFilter = WEBGL_FILTERS[sampler.magFilter] || THREE.LinearFilter
                    texture.minFilter = WEBGL_FILTERS[sampler.minFilter] || THREE.LinearMipmapLinearFilter
                    texture.wrapS = WEBGL_WRAPPINGS[sampler.wrapS] || THREE.RepeatWrapping
                    texture.wrapT = WEBGL_WRAPPINGS[sampler.wrapT] || THREE.RepeatWrapping
                    parser.associations.set(texture, {
                        textures: textureIndex,
                    })
                    return texture
                })
                .catch(function () {
                    return null
                })
            this.textureCache[cacheKey] = promise
            return promise
        }

        loadImageSource(sourceIndex, loader) {
            const parser = this
            const json = this.json
            const options = this.options

            if (this.sourceCache[sourceIndex] !== undefined) {
                return this.sourceCache[sourceIndex].then(texture => texture.clone())
            }

            const sourceDef = json.images[sourceIndex]
            const URL = self.URL || self.webkitURL
            let sourceURI = sourceDef.uri || ''
            let isObjectURL = false

            if (sourceDef.bufferView !== undefined) {
                // Load binary image data from bufferView, if provided.
                sourceURI = parser.getDependency('bufferView', sourceDef.bufferView).then(function (bufferView) {
                    isObjectURL = true
                    const blob = new Blob([bufferView], {
                        type: sourceDef.mimeType,
                    })
                    sourceURI = URL.createObjectURL(blob)
                    return sourceURI
                })
            } else if (sourceDef.uri === undefined) {
                throw new Error('THREE.GLTFLoader: Image ' + sourceIndex + ' is missing URI and bufferView')
            }

            const promise = Promise.resolve(sourceURI)
                .then(function (sourceURI) {
                    return new Promise(function (resolve, reject) {
                        let onLoad = resolve

                        if (loader.isImageBitmapLoader === true) {
                            onLoad = function (imageBitmap) {
                                const texture = new THREE.Texture(imageBitmap)
                                texture.needsUpdate = true
                                resolve(texture)
                            }
                        }

                        loader.load(THREE.LoaderUtils.resolveURL(sourceURI, options.path), onLoad, undefined, reject)
                    })
                })
                .then(function (texture) {
                    // Clean up resources and configure THREE.Texture.
                    if (isObjectURL === true) {
                        URL.revokeObjectURL(sourceURI)
                    }

                    texture.userData.mimeType = sourceDef.mimeType || getImageURIMimeType(sourceDef.uri)
                    return texture
                })
                .catch(function (error) {
                    console.error("THREE.GLTFLoader: Couldn't load texture", sourceURI)
                    throw error
                })
            this.sourceCache[sourceIndex] = promise
            return promise
        }
        /**
         * Asynchronously assigns a texture to the given material parameters.
         * @param {Object} materialParams
         * @param {string} mapName
         * @param {Object} mapDef
         * @return {Promise<Texture>}
         */

        assignTexture(materialParams, mapName, mapDef, encoding) {
            const 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]) {
                    const transform = mapDef.extensions !== undefined ? mapDef.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM] : undefined

                    if (transform) {
                        const gltfReference = parser.associations.get(texture)
                        texture = parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM].extendTexture(texture, transform)
                        parser.associations.set(texture, gltfReference)
                    }
                }

                if (encoding !== undefined) {
                    texture.encoding = encoding
                }

                materialParams[mapName] = texture
                return texture
            })
        }
        /**
         * Assigns final material to a THREE.Mesh, THREE.Line, or THREE.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 accommodate different primitive types, defines, etc. New materials will
         * be created if necessary, and reused from a cache.
         * @param  {Object3D} mesh THREE.Mesh, THREE.Line, or THREE.Points instance.
         */

        assignFinalMaterial(mesh) {
            const geometry = mesh.geometry
            let material = mesh.material
            const useDerivativeTangents = geometry.attributes.tangent === undefined
            const useVertexColors = geometry.attributes.color !== undefined
            const useFlatShading = geometry.attributes.normal === undefined

            if (mesh.isPoints) {
                const cacheKey = 'PointsMaterial:' + material.uuid
                let pointsMaterial = this.cache.get(cacheKey)

                if (!pointsMaterial) {
                    pointsMaterial = new THREE.PointsMaterial()
                    THREE.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) {
                const cacheKey = 'LineBasicMaterial:' + material.uuid
                let lineMaterial = this.cache.get(cacheKey)

                if (!lineMaterial) {
                    lineMaterial = new THREE.LineBasicMaterial()
                    THREE.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 (useDerivativeTangents || useVertexColors || useFlatShading) {
                let cacheKey = 'ClonedMaterial:' + material.uuid + ':'
                if (material.isGLTFSpecularGlossinessMaterial) cacheKey += 'specular-glossiness:'
                if (useDerivativeTangents) cacheKey += 'derivative-tangents:'
                if (useVertexColors) cacheKey += 'vertex-colors:'
                if (useFlatShading) cacheKey += 'flat-shading:'
                let cachedMaterial = this.cache.get(cacheKey)

                if (!cachedMaterial) {
                    cachedMaterial = material.clone()
                    if (useVertexColors) cachedMaterial.vertexColors = true
                    if (useFlatShading) cachedMaterial.flatShading = true

                    if (useDerivativeTangents) {
                        // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
                        if (cachedMaterial.normalScale) cachedMaterial.normalScale.y *= -1
                        if (cachedMaterial.clearcoatNormalScale) cachedMaterial.clearcoatNormalScale.y *= -1
                    }

                    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)
            }

            mesh.material = material
        }

        getMaterialType() {
            return THREE.MeshStandardMaterial
        }
        /**
         * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
         * @param {number} materialIndex
         * @return {Promise<Material>}
         */

        loadMaterial(materialIndex) {
            const parser = this
            const json = this.json
            const extensions = this.extensions
            const materialDef = json.materials[materialIndex]
            let materialType
            const materialParams = {}
            const materialExtensions = materialDef.extensions || {}
            const pending = []

            if (materialExtensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS]) {
                const 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]) {
                const 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
                const metallicRoughness = materialDef.pbrMetallicRoughness || {}
                materialParams.color = new THREE.Color(1.0, 1.0, 1.0)
                materialParams.opacity = 1.0

                if (Array.isArray(metallicRoughness.baseColorFactor)) {
                    const array = metallicRoughness.baseColorFactor
                    materialParams.color.fromArray(array)
                    materialParams.opacity = array[3]
                }

                if (metallicRoughness.baseColorTexture !== undefined) {
                    pending.push(parser.assignTexture(materialParams, 'map', metallicRoughness.baseColorTexture, THREE.sRGBEncoding))
                }

                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 = THREE.DoubleSide
            }

            const 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 !== THREE.MeshBasicMaterial) {
                pending.push(parser.assignTexture(materialParams, 'normalMap', materialDef.normalTexture))
                materialParams.normalScale = new THREE.Vector2(1, 1)

                if (materialDef.normalTexture.scale !== undefined) {
                    const scale = materialDef.normalTexture.scale
                    materialParams.normalScale.set(scale, scale)
                }
            }

            if (materialDef.occlusionTexture !== undefined && materialType !== THREE.MeshBasicMaterial) {
                pending.push(parser.assignTexture(materialParams, 'aoMap', materialDef.occlusionTexture))

                if (materialDef.occlusionTexture.strength !== undefined) {
                    materialParams.aoMapIntensity = materialDef.occlusionTexture.strength
                }
            }

            if (materialDef.emissiveFactor !== undefined && materialType !== THREE.MeshBasicMaterial) {
                materialParams.emissive = new THREE.Color().fromArray(materialDef.emissiveFactor)
            }

            if (materialDef.emissiveTexture !== undefined && materialType !== THREE.MeshBasicMaterial) {
                pending.push(parser.assignTexture(materialParams, 'emissiveMap', materialDef.emissiveTexture, THREE.sRGBEncoding))
            }

            return Promise.all(pending).then(function () {
                let 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
                assignExtrasToUserData(material, materialDef)
                parser.associations.set(material, {
                    materials: materialIndex,
                })
                if (materialDef.extensions) addUnknownExtensionsToUserData(extensions, material, materialDef)
                return material
            })
        }
        /** When THREE.Object3D instances are targeted by animation, they need unique names. */

        createUniqueName(originalName) {
            const sanitizedName = THREE.PropertyBinding.sanitizeNodeName(originalName || '')
            let name = sanitizedName

            for (let i = 1; this.nodeNamesUsed[name]; ++i) {
                name = sanitizedName + '_' + i
            }

            this.nodeNamesUsed[name] = true
            return name
        }
        /**
         * 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>>}
         */

        loadGeometries(primitives) {
            const parser = this
            const extensions = this.extensions
            const cache = this.primitiveCache

            function createDracoPrimitive(primitive) {
                return extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION].decodePrimitive(primitive, parser).then(function (geometry) {
                    return addPrimitiveAttributes(geometry, primitive, parser)
                })
            }

            const pending = []

            for (let i = 0, il = primitives.length; i < il; i++) {
                const primitive = primitives[i]
                const cacheKey = createPrimitiveKey(primitive) // See if we've already created this geometry

                const cached = cache[cacheKey]

                if (cached) {
                    // Use the cached geometry if it exists
                    pending.push(cached.promise)
                } else {
                    let 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 THREE.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>}
         */

        loadMesh(meshIndex) {
            const parser = this
            const json = this.json
            const extensions = this.extensions
            const meshDef = json.meshes[meshIndex]
            const primitives = meshDef.primitives
            const pending = []

            for (let i = 0, il = primitives.length; i < il; i++) {
                const 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) {
                const materials = results.slice(0, results.length - 1)
                const geometries = results[results.length - 1]
                const meshes = []

                for (let i = 0, il = geometries.length; i < il; i++) {
                    const geometry = geometries[i]
                    const primitive = primitives[i] // 1. create THREE.Mesh

                    let mesh
                    const 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 THREE.SkinnedMesh(geometry, material) : new THREE.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, THREE.TriangleStripDrawMode)
                        } else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {
                            mesh.geometry = toTrianglesDrawMode(mesh.geometry, THREE.TriangleFanDrawMode)
                        }
                    } else if (primitive.mode === WEBGL_CONSTANTS.LINES) {
                        mesh = new THREE.LineSegments(geometry, material)
                    } else if (primitive.mode === WEBGL_CONSTANTS.LINE_STRIP) {
                        mesh = new THREE.Line(geometry, material)
                    } else if (primitive.mode === WEBGL_CONSTANTS.LINE_LOOP) {
                        mesh = new THREE.LineLoop(geometry, material)
                    } else if (primitive.mode === WEBGL_CONSTANTS.POINTS) {
                        mesh = new THREE.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)
                    if (primitive.extensions) addUnknownExtensionsToUserData(extensions, mesh, primitive)
                    parser.assignFinalMaterial(mesh)
                    meshes.push(mesh)
                }

                for (let i = 0, il = meshes.length; i < il; i++) {
                    parser.associations.set(meshes[i], {
                        meshes: meshIndex,
                        primitives: i,
                    })
                }

                if (meshes.length === 1) {
                    return meshes[0]
                }

                const group = new THREE.Group()
                parser.associations.set(group, {
                    meshes: meshIndex,
                })

                for (let 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>}
         */

        loadCamera(cameraIndex) {
            let camera
            const cameraDef = this.json.cameras[cameraIndex]
            const params = cameraDef[cameraDef.type]

            if (!params) {
                console.warn('THREE.GLTFLoader: Missing camera parameters.')
                return
            }

            if (cameraDef.type === 'perspective') {
                camera = new THREE.PerspectiveCamera(THREE.MathUtils.radToDeg(params.yfov), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6)
            } else if (cameraDef.type === 'orthographic') {
                camera = new THREE.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>}
         */

        loadSkin(skinIndex) {
            const skinDef = this.json.skins[skinIndex]
            const 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>}
         */

        loadAnimation(animationIndex) {
            const json = this.json
            const animationDef = json.animations[animationIndex]
            const pendingNodes = []
            const pendingInputAccessors = []
            const pendingOutputAccessors = []
            const pendingSamplers = []
            const pendingTargets = []

            for (let i = 0, il = animationDef.channels.length; i < il; i++) {
                const channel = animationDef.channels[i]
                const sampler = animationDef.samplers[channel.sampler]
                const target = channel.target
                const name = target.node
                const input = animationDef.parameters !== undefined ? animationDef.parameters[sampler.input] : sampler.input
                const 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) {
                    const nodes = dependencies[0]
                    const inputAccessors = dependencies[1]
                    const outputAccessors = dependencies[2]
                    const samplers = dependencies[3]
                    const targets = dependencies[4]
                    const tracks = []

                    for (let i = 0, il = nodes.length; i < il; i++) {
                        const node = nodes[i]
                        const inputAccessor = inputAccessors[i]
                        const outputAccessor = outputAccessors[i]
                        const sampler = samplers[i]
                        const target = targets[i]
                        if (node === undefined) continue
                        node.updateMatrix()
                        let TypedKeyframeTrack

                        switch (PATH_PROPERTIES[target.path]) {
                            case PATH_PROPERTIES.weights:
                                TypedKeyframeTrack = THREE.NumberKeyframeTrack
                                break

                            case PATH_PROPERTIES.rotation:
                                TypedKeyframeTrack = THREE.QuaternionKeyframeTrack
                                break

                            case PATH_PROPERTIES.position:
                            case PATH_PROPERTIES.scale:
                            default:
                                TypedKeyframeTrack = THREE.VectorKeyframeTrack
                                break
                        }

                        const targetName = node.name ? node.name : node.uuid
                        const interpolation = sampler.interpolation !== undefined ? INTERPOLATION[sampler.interpolation] : THREE.InterpolateLinear
                        const targetNames = []

                        if (PATH_PROPERTIES[target.path] === PATH_PROPERTIES.weights) {
                            node.traverse(function (object) {
                                if (object.morphTargetInfluences) {
                                    targetNames.push(object.name ? object.name : object.uuid)
                                }
                            })
                        } else {
                            targetNames.push(targetName)
                        }

                        let outputArray = outputAccessor.array

                        if (outputAccessor.normalized) {
                            const scale = getNormalizedComponentScale(outputArray.constructor)
                            const scaled = new Float32Array(outputArray.length)

                            for (let j = 0, jl = outputArray.length; j < jl; j++) {
                                scaled[j] = outputArray[j] * scale
                            }

                            outputArray = scaled
                        }

                        for (let j = 0, jl = targetNames.length; j < jl; j++) {
                            const 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.
                                    const interpolantType = this instanceof THREE.QuaternionKeyframeTrack ? GLTFCubicSplineQuaternionInterpolant : GLTFCubicSplineInterpolant
                                    return new interpolantType(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)
                        }
                    }

                    const name = animationDef.name ? animationDef.name : 'animation_' + animationIndex
                    return new THREE.AnimationClip(name, undefined, tracks)
                }
            )
        }

        createNodeMesh(nodeIndex) {
            const json = this.json
            const parser = this
            const nodeDef = json.nodes[nodeIndex]
            if (nodeDef.mesh === undefined) return null
            return parser.getDependency('mesh', nodeDef.mesh).then(function (mesh) {
                const 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 (let i = 0, il = nodeDef.weights.length; i < il; i++) {
                            o.morphTargetInfluences[i] = nodeDef.weights[i]
                        }
                    })
                }

                return node
            })
        }
        /**
         * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
         * @param {number} nodeIndex
         * @return {Promise<Object3D>}
         */

        loadNode(nodeIndex) {
            const json = this.json
            const extensions = this.extensions
            const parser = this
            const nodeDef = json.nodes[nodeIndex] // reserve node's name before its dependencies, so the root has the intended name.

            const nodeName = nodeDef.name ? parser.createUniqueName(nodeDef.name) : ''
            return (function () {
                const pending = []

                const meshPromise = parser._invokeOne(function (ext) {
                    return ext.createNodeMesh && ext.createNodeMesh(nodeIndex)
                })

                if (meshPromise) {
                    pending.push(meshPromise)
                }

                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) {
                let node // .isBone isn't in glTF spec. See ._markDefs

                if (nodeDef.isBone === true) {
                    node = new THREE.Bone()
                } else if (objects.length > 1) {
                    node = new THREE.Group()
                } else if (objects.length === 1) {
                    node = objects[0]
                } else {
                    node = new THREE.Object3D()
                }

                if (node !== objects[0]) {
                    for (let 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) {
                    const matrix = new THREE.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)
                    }
                }

                if (!parser.associations.has(node)) {
                    parser.associations.set(node, {})
                }

                parser.associations.get(node).nodes = nodeIndex
                return node
            })
        }
        /**
         * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
         * @param {number} sceneIndex
         * @return {Promise<Group>}
         */

        loadScene(sceneIndex) {
            const json = this.json
            const extensions = this.extensions
            const sceneDef = this.json.scenes[sceneIndex]
            const parser = this // THREE.Loader returns THREE.Group, not Scene.
            // See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172

            const scene = new THREE.Group()
            if (sceneDef.name) scene.name = parser.createUniqueName(sceneDef.name)
            assignExtrasToUserData(scene, sceneDef)
            if (sceneDef.extensions) addUnknownExtensionsToUserData(extensions, scene, sceneDef)
            const nodeIds = sceneDef.nodes || []
            const pending = []

            for (let i = 0, il = nodeIds.length; i < il; i++) {
                pending.push(buildNodeHierarchy(nodeIds[i], scene, json, parser))
            }

            return Promise.all(pending).then(function () {
                // Removes dangling associations, associations that reference a node that
                // didn't make it into the scene.
                const reduceAssociations = node => {
                    const reducedAssociations = new Map()

                    for (const [key, value] of parser.associations) {
                        if (key instanceof THREE.Material || key instanceof THREE.Texture) {
                            reducedAssociations.set(key, value)
                        }
                    }

                    node.traverse(node => {
                        const mappings = parser.associations.get(node)

                        if (mappings != null) {
                            reducedAssociations.set(node, mappings)
                        }
                    })
                    return reducedAssociations
                }

                parser.associations = reduceAssociations(scene)
                return scene
            })
        }
    }

    function buildNodeHierarchy(nodeId, parentObject, json, parser) {
        const nodeDef = json.nodes[nodeId]
        return parser
            .getDependency('node', nodeId)
            .then(function (node) {
                if (nodeDef.skin === undefined) return node // build skeleton here as well

                let skinEntry
                return parser
                    .getDependency('skin', nodeDef.skin)
                    .then(function (skin) {
                        skinEntry = skin
                        const pendingJoints = []

                        for (let 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
                            const bones = []
                            const boneInverses = []

                            for (let j = 0, jl = jointNodes.length; j < jl; j++) {
                                const jointNode = jointNodes[j]

                                if (jointNode) {
                                    bones.push(jointNode)
                                    const mat = new THREE.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 THREE.Skeleton(bones, boneInverses), mesh.matrixWorld)
                        })
                        return node
                    })
            })
            .then(function (node) {
                // build node hierachy
                parentObject.add(node)
                const pending = []

                if (nodeDef.children) {
                    const children = nodeDef.children

                    for (let i = 0, il = children.length; i < il; i++) {
                        const child = children[i]
                        pending.push(buildNodeHierarchy(child, node, json, parser))
                    }
                }

                return Promise.all(pending)
            })
    }
    /**
     * @param {BufferGeometry} geometry
     * @param {GLTF.Primitive} primitiveDef
     * @param {GLTFParser} parser
     */

    function computeBounds(geometry, primitiveDef, parser) {
        const attributes = primitiveDef.attributes
        const box = new THREE.Box3()

        if (attributes.POSITION !== undefined) {
            const accessor = parser.json.accessors[attributes.POSITION]
            const min = accessor.min
            const 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 THREE.Vector3(min[0], min[1], min[2]), new THREE.Vector3(max[0], max[1], max[2]))

                if (accessor.normalized) {
                    const boxScale = getNormalizedComponentScale(WEBGL_COMPONENT_TYPES[accessor.componentType])
                    box.min.multiplyScalar(boxScale)
                    box.max.multiplyScalar(boxScale)
                }
            } else {
                console.warn('THREE.GLTFLoader: Missing min/max properties for accessor POSITION.')
                return
            }
        } else {
            return
        }

        const targets = primitiveDef.targets

        if (targets !== undefined) {
            const maxDisplacement = new THREE.Vector3()
            const vector = new THREE.Vector3()

            for (let i = 0, il = targets.length; i < il; i++) {
                const target = targets[i]

                if (target.POSITION !== undefined) {
                    const accessor = parser.json.accessors[target.POSITION]
                    const min = accessor.min
                    const 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])))

                        if (accessor.normalized) {
                            const boxScale = getNormalizedComponentScale(WEBGL_COMPONENT_TYPES[accessor.componentType])
                            vector.multiplyScalar(boxScale)
                        } // 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
        const sphere = new THREE.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) {
        const attributes = primitiveDef.attributes
        const pending = []

        function assignAttributeAccessor(accessorIndex, attributeName) {
            return parser.getDependency('accessor', accessorIndex).then(function (accessor) {
                geometry.setAttribute(attributeName, accessor)
            })
        }

        for (const gltfAttributeName in attributes) {
            const 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) {
            const 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) {
        let index = geometry.getIndex() // generate index if not present

        if (index === null) {
            const indices = []
            const position = geometry.getAttribute('position')

            if (position !== undefined) {
                for (let 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
            }
        } //

        const numberOfTriangles = index.count - 2
        const newIndices = []

        if (drawMode === THREE.TriangleFanDrawMode) {
            // gl.TRIANGLE_FAN
            for (let 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 (let 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

        const newGeometry = geometry.clone()
        newGeometry.setIndex(newIndices)
        return newGeometry
    }

    THREE.GLTFLoader = GLTFLoader
})()