import {
    AnimationClip,
    Bone,
    Box3,
    BufferAttribute,
    BufferGeometry,
    ClampToEdgeWrapping,
    Color,
    DirectionalLight,
    DoubleSide,
    FileLoader,
    FrontSide,
    Group,
    ImageBitmapLoader,
    InterleavedBuffer,
    InterleavedBufferAttribute,
    Interpolant,
    InterpolateDiscrete,
    InterpolateLinear,
    Line,
    LineBasicMaterial,
    LineLoop,
    LineSegments,
    LinearFilter,
    LinearMipmapLinearFilter,
    LinearMipmapNearestFilter,
    Loader,
    LoaderUtils,
    Material,
    MathUtils,
    Matrix4,
    Mesh,
    MeshBasicMaterial,
    MeshPhysicalMaterial,
    MeshStandardMaterial,
    MirroredRepeatWrapping,
    NearestFilter,
    NearestMipmapLinearFilter,
    NearestMipmapNearestFilter,
    NumberKeyframeTrack,
    Object3D,
    OrthographicCamera,
    PerspectiveCamera,
    PointLight,
    Points,
    PointsMaterial,
    PropertyBinding,
    Quaternion,
    QuaternionKeyframeTrack,
    RepeatWrapping,
    Skeleton,
    SkinnedMesh,
    Sphere,
    SpotLight,
    TangentSpaceNormalMap,
    Texture,
    TextureLoader,
    TriangleFanDrawMode,
    TriangleStripDrawMode,
    Vector2,
    Vector3,
    VectorKeyframeTrack,
    sRGBEncoding
} from '../lib/three.module.js'

import { DRACOLoader } from './DRACOLoader.js'

class GLTFLoader extends Loader {
    constructor(manager) {
        super(manager)

        // bimrocket
        this.dracoLoader = new DRACOLoader().setDecoderPath('js/lib/draco/')
        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 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 = 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 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 = LoaderUtils.decodeText(new Uint8Array(data, 0, 4))

            if (magic === BINARY_EXTENSION_HEADER_MAGIC) {
                try {
                    extensions[EXTENSIONS.KHR_BINARY_GLTF] = new GLTFBinaryExtension(data)
                } catch (error) {
                    if (onError) onError(error)
                    return
                }

                content = extensions[EXTENSIONS.KHR_BINARY_GLTF].content
            } else {
                content = LoaderUtils.decodeText(new Uint8Array(data))
            }
        }

        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_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

        // 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 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 DirectionalLight(color)
                lightNode.target.position.set(0, 0, -1)
                lightNode.add(lightNode.target)
                break

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

            case 'spot':
                lightNode = new SpotLight(color)
                lightNode.distance = range
                // Handle spotlight properties.
                lightDef.spot = lightDef.spot || {}
                lightDef.spot.innerConeAngle = lightDef.spot.innerConeAngle !== undefined ? lightDef.spot.innerConeAngle : 0
                lightDef.spot.outerConeAngle = lightDef.spot.outerConeAngle !== undefined ? lightDef.spot.outerConeAngle : Math.PI / 4.0
                lightNode.angle = lightDef.spot.outerConeAngle
                lightNode.penumbra = 1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle
                lightNode.target.position.set(0, 0, -1)
                lightNode.add(lightNode.target)
                break

            default:
                throw new Error('THREE.GLTFLoader: Unexpected light type: ' + lightDef.type)
        }

        // Some lights (e.g. spot) default to a position other than the origin. Reset the position
        // here, because node-level parsing will only override position if explicitly specified.
        lightNode.position.set(0, 0, 0)

        lightNode.decay = 2

        if (lightDef.intensity !== undefined) lightNode.intensity = lightDef.intensity

        lightNode.name = parser.createUniqueName(lightDef.name || 'light_' + lightIndex)

        dependency = Promise.resolve(lightNode)

        parser.cache.add(cacheKey, dependency)

        return dependency
    }

    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 MeshBasicMaterial
    }

    extendParams(materialParams, materialDef, parser) {
        const pending = []

        materialParams.color = new 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, 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 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 Vector2(scale, scale)
            }
        }

        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 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 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, 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 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 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 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 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 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 Color(colorArray[0], colorArray[1], colorArray[2])

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

        return Promise.all(pending)
    }
}

/**
 * BasisU 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 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 Promise.all([buffer, decoder.ready]).then(function(res) {
                const byteOffset = extensionDef.byteOffset || 0
                const byteLength = extensionDef.byteLength || 0

                const count = extensionDef.count
                const stride = extensionDef.byteStride

                const result = new ArrayBuffer(count * stride)
                const source = new Uint8Array(res[0], byteOffset, byteLength)

                decoder.decodeGltfBuffer(new Uint8Array(result), count, stride, source, extensionDef.mode, extensionDef.filter)
                return result
            })
        } else {
            return null
        }
    }
}

/* BINARY EXTENSION */
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: 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 = 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 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
                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
                )
            })
        })
    }
}

/**
 * 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 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 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 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, sRGBEncoding))
        }

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

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

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

/**
 * 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 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
    }
}

GLTFCubicSplineInterpolant.prototype.beforeStart_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_

GLTFCubicSplineInterpolant.prototype.afterEnd_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_

GLTFCubicSplineInterpolant.prototype.interpolate_ = function(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 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: NearestFilter,
    9729: LinearFilter,
    9984: NearestMipmapNearestFilter,
    9985: LinearMipmapNearestFilter,
    9986: NearestMipmapLinearFilter,
    9987: LinearMipmapLinearFilter
}

const WEBGL_WRAPPINGS = {
    33071: ClampToEdgeWrapping,
    33648: MirroredRepeatWrapping,
    10497: 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: InterpolateLinear,
    STEP: 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 MeshStandardMaterial({
            color: 0xffffff,
            emissive: 0x000000,
            metalness: 1,
            roughness: 1,
            transparent: false,
            depthTest: true,
            side: FrontSide
        })
    }

    return cache['DefaultMaterial']
}

function addUnknownExtensionsToUserData(knownExtensions, object, objectDef) {
    // Add unknown glTF extensions to an object's userData.

    for (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()

        // BufferGeometry caching
        this.primitiveCache = {}

        // 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 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 TextureLoader(this.options.manager)
        } else {
            this.textureLoader = new ImageBitmapLoader(this.options.manager)
        }

        this.textureLoader.setCrossOrigin(this.options.crossOrigin)
        this.textureLoader.setRequestHeader(this.options.requestHeader)

        this.fileLoader = new 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: {}
                }

                // bimrocket: Z_UP
                const rotMatrix = new Matrix4().makeRotationX(Math.PI / 2)
                for (let child of result.scene.children) {
                    child.updateMatrix()
                    child.matrix.premultiply(rotMatrix) // rotate object 90 deg
                    child.matrix.decompose(child.position, child.quaternion, child.scale)
                }

                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 Bone or an
        // 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 SkinnedMesh or Mesh. Use the node's mesh reference
                // to mark SkinnedMesh if node has skin.
                if (nodeDef.skin !== undefined) {
                    meshDefs[nodeDef.mesh].isSkinnedMesh = true
                }
            }

            if (nodeDef.camera !== undefined) {
                this._addNodeRef(this.cameraCache, nodeDef.camera)
            }
        }
    }

    /**
     * Counts references to shared node / Object3D resources. These resources
     * can be reused, or "instantiated", at multiple nodes in the scene
     * hierarchy. Mesh, Camera, and Light instances are instantiated and must
     * be marked. Non-scenegraph resources (like Materials, Geometries, and
     * Textures) can be reused directly and are not marked here.
     *
     * Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
     */
    _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(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 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 InterleavedBuffer(array, byteStride / elementBytes)

                    parser.cache.add(ibCacheKey, ib)
                }

                bufferAttribute = new InterleavedBufferAttribute(ib, itemSize, (byteOffset % byteStride) / elementBytes, normalized)
            } else {
                if (bufferView === null) {
                    array = new TypedArray(accessorDef.count * itemSize)
                } else {
                    array = new TypedArray(bufferView, byteOffset, accessorDef.count * itemSize)
                }

                bufferAttribute = new BufferAttribute(array, itemSize, normalized)
            }

            // https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
            if (accessorDef.sparse !== undefined) {
                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 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 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] || LinearFilter
                texture.minFilter = WEBGL_FILTERS[sampler.minFilter] || LinearMipmapLinearFilter
                texture.wrapS = WEBGL_WRAPPINGS[sampler.wrapS] || RepeatWrapping
                texture.wrapT = WEBGL_WRAPPINGS[sampler.wrapT] || RepeatWrapping

                parser.associations.set(texture, { 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 Texture(imageBitmap)
                            texture.needsUpdate = true

                            resolve(texture)
                        }
                    }

                    loader.load(LoaderUtils.resolveURL(sourceURI, options.path), onLoad, undefined, reject)
                })
            })
            .then(function(texture) {
                // Clean up resources and configure 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 Mesh, Line, or Points instance. The instance
     * already has a material (generated from the glTF material options alone)
     * but reuse of the same glTF material may require multiple threejs materials
     * to accommodate different primitive types, defines, etc. New materials will
     * be created if necessary, and reused from a cache.
     * @param  {Object3D} mesh Mesh, Line, or Points instance.
     */
    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 PointsMaterial()
                Material.prototype.copy.call(pointsMaterial, material)
                pointsMaterial.color.copy(material.color)
                pointsMaterial.map = material.map
                pointsMaterial.sizeAttenuation = false // glTF spec says points should be 1px

                this.cache.add(cacheKey, pointsMaterial)
            }

            material = pointsMaterial
        } else if (mesh.isLine) {
            const cacheKey = 'LineBasicMaterial:' + material.uuid

            let lineMaterial = this.cache.get(cacheKey)

            if (!lineMaterial) {
                lineMaterial = new LineBasicMaterial()
                Material.prototype.copy.call(lineMaterial, material)
                lineMaterial.color.copy(material.color)

                this.cache.add(cacheKey, lineMaterial)
            }

            material = lineMaterial
        }

        // Clone the material if it will be modified
        if (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(/* materialIndex */) {
        return 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 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, 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 = 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 !== MeshBasicMaterial) {
            pending.push(parser.assignTexture(materialParams, 'normalMap', materialDef.normalTexture))

            materialParams.normalScale = new Vector2(1, 1)

            if (materialDef.normalTexture.scale !== undefined) {
                const scale = materialDef.normalTexture.scale

                materialParams.normalScale.set(scale, scale)
            }
        }

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

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

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

        if (materialDef.emissiveTexture !== undefined && materialType !== MeshBasicMaterial) {
            pending.push(parser.assignTexture(materialParams, 'emissiveMap', materialDef.emissiveTexture, 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 Object3D instances are targeted by animation, they need unique names. */
    createUniqueName(originalName) {
        const sanitizedName = 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 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 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 SkinnedMesh(geometry, material) : new Mesh(geometry, material)

                    if (mesh.isSkinnedMesh === true && !mesh.geometry.attributes.skinWeight.normalized) {
                        // we normalize floating point skin weight array to fix malformed assets (see #15319)
                        // it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
                        mesh.normalizeSkinWeights()
                    }

                    if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP) {
                        mesh.geometry = toTrianglesDrawMode(mesh.geometry, TriangleStripDrawMode)
                    } else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {
                        mesh.geometry = toTrianglesDrawMode(mesh.geometry, TriangleFanDrawMode)
                    }
                } else if (primitive.mode === WEBGL_CONSTANTS.LINES) {
                    mesh = new LineSegments(geometry, material)
                } else if (primitive.mode === WEBGL_CONSTANTS.LINE_STRIP) {
                    mesh = new Line(geometry, material)
                } else if (primitive.mode === WEBGL_CONSTANTS.LINE_LOOP) {
                    mesh = new LineLoop(geometry, material)
                } else if (primitive.mode === WEBGL_CONSTANTS.POINTS) {
                    mesh = new Points(geometry, material)
                } else {
                    throw new Error('THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode)
                }

                if (Object.keys(mesh.geometry.morphAttributes).length > 0) {
                    updateMorphTargets(mesh, meshDef)
                }

                mesh.name = parser.createUniqueName(meshDef.name || 'mesh_' + meshIndex)

                assignExtrasToUserData(mesh, meshDef)

                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 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 PerspectiveCamera(MathUtils.radToDeg(params.yfov), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6)
        } else if (cameraDef.type === 'orthographic') {
            camera = new OrthographicCamera(-params.xmag, params.xmag, params.ymag, -params.ymag, params.znear, params.zfar)
        }

        if (cameraDef.name) camera.name = this.createUniqueName(cameraDef.name)

        assignExtrasToUserData(camera, cameraDef)

        return Promise.resolve(camera)
    }

    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
     * @param {number} skinIndex
     * @return {Promise<Object>}
     */
    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 !== undefined ? target.node : target.id // NOTE: target.id is deprecated.
            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()
                    node.matrixAutoUpdate = true

                    let TypedKeyframeTrack

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

                        case PATH_PROPERTIES.rotation:
                            TypedKeyframeTrack = QuaternionKeyframeTrack
                            break

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

                    const targetName = node.name ? node.name : node.uuid

                    const interpolation = sampler.interpolation !== undefined ? INTERPOLATION[sampler.interpolation] : 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 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 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 Bone()
            } else if (objects.length > 1) {
                node = new Group()
            } else if (objects.length === 1) {
                node = objects[0]
            } else {
                node = new Object3D()
            }

            if (node !== objects[0]) {
                for (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 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

        // Loader returns Group, not Scene.
        // See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172
        const scene = new 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 Material || key instanceof 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 Matrix4()

                                if (skinEntry.inverseBindMatrices !== undefined) {
                                    mat.fromArray(skinEntry.inverseBindMatrices.array, j * 16)
                                }

                                boneInverses.push(mat)
                            } else {
                                console.warn('THREE.GLTFLoader: Joint "%s" could not be found.', skinEntry.joints[j])
                            }
                        }

                        mesh.bind(new Skeleton(bones, boneInverses), mesh.matrixWorld)
                    })

                    return node
                })
        })
        .then(function(node) {
            // build node hierachy

            parentObject.add(node)

            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 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 Vector3(min[0], min[1], min[2]), new 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 Vector3()
        const vector = new 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 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 === 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
}

export { GLTFLoader }