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about-Leaflet / GLTFLoader.js
@SugawaraMiyu SugawaraMiyu on 3 Jun 2024 117 KB GLTFLoader.js
( function () {
     
    	class GLTFLoader extends THREE.Loader {
     
    		constructor( manager ) {
     
    			super( manager );
    			this.dracoLoader = null;
    			this.ktx2Loader = null;
    			this.meshoptDecoder = null;
    			this.pluginCallbacks = [];
    			this.register( function ( parser ) {
     
    				return new GLTFMaterialsClearcoatExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFTextureBasisUExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFTextureWebPExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMaterialsSheenExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMaterialsTransmissionExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMaterialsVolumeExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMaterialsIorExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMaterialsEmissiveStrengthExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMaterialsSpecularExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMaterialsIridescenceExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFLightsExtension( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMeshoptCompression( parser );
     
    			} );
    			this.register( function ( parser ) {
     
    				return new GLTFMeshGpuInstancing( parser );
     
    			} );
     
    		}
    		load( url, onLoad, onProgress, onError ) {
     
    			const scope = this;
    			let resourcePath;
    			if ( this.resourcePath !== '' ) {
     
    				resourcePath = this.resourcePath;
     
    			} else if ( this.path !== '' ) {
     
    				resourcePath = this.path;
     
    			} else {
     
    				resourcePath = THREE.LoaderUtils.extractUrlBase( url );
     
    			}
     
    			// Tells the LoadingManager to track an extra item, which resolves after
    			// the model is fully loaded. This means the count of items loaded will
    			// be incorrect, but ensures manager.onLoad() does not fire early.
    			this.manager.itemStart( url );
    			const _onError = function ( e ) {
     
    				if ( onError ) {
     
    					onError( e );
     
    				} else {
     
    					console.error( e );
     
    				}
     
    				scope.manager.itemError( url );
    				scope.manager.itemEnd( url );
     
    			};
     
    			const loader = new THREE.FileLoader( this.manager );
    			loader.setPath( this.path );
    			loader.setResponseType( 'arraybuffer' );
    			loader.setRequestHeader( this.requestHeader );
    			loader.setWithCredentials( this.withCredentials );
    			loader.load( url, function ( data ) {
     
    				try {
     
    					scope.parse( data, resourcePath, function ( gltf ) {
     
    						onLoad( gltf );
    						scope.manager.itemEnd( url );
     
    					}, _onError );
     
    				} catch ( e ) {
     
    					_onError( e );
     
    				}
     
    			}, onProgress, _onError );
     
    		}
    		setDRACOLoader( dracoLoader ) {
     
    			this.dracoLoader = dracoLoader;
    			return this;
     
    		}
    		setDDSLoader() {
     
    			throw new Error( 'THREE.GLTFLoader: "MSFT_texture_dds" no longer supported. Please update to "KHR_texture_basisu".' );
     
    		}
    		setKTX2Loader( ktx2Loader ) {
     
    			this.ktx2Loader = ktx2Loader;
    			return this;
     
    		}
    		setMeshoptDecoder( meshoptDecoder ) {
     
    			this.meshoptDecoder = meshoptDecoder;
    			return this;
     
    		}
    		register( callback ) {
     
    			if ( this.pluginCallbacks.indexOf( callback ) === - 1 ) {
     
    				this.pluginCallbacks.push( callback );
     
    			}
     
    			return this;
     
    		}
    		unregister( callback ) {
     
    			if ( this.pluginCallbacks.indexOf( callback ) !== - 1 ) {
     
    				this.pluginCallbacks.splice( this.pluginCallbacks.indexOf( callback ), 1 );
     
    			}
     
    			return this;
     
    		}
    		parse( data, path, onLoad, onError ) {
     
    			let json;
    			const extensions = {};
    			const plugins = {};
    			if ( typeof data === 'string' ) {
     
    				json = JSON.parse( data );
     
    			} else if ( data instanceof ArrayBuffer ) {
     
    				const magic = THREE.LoaderUtils.decodeText( new Uint8Array( data, 0, 4 ) );
    				if ( magic === BINARY_EXTENSION_HEADER_MAGIC ) {
     
    					try {
     
    						extensions[ EXTENSIONS.KHR_BINARY_GLTF ] = new GLTFBinaryExtension( data );
     
    					} catch ( error ) {
     
    						if ( onError ) onError( error );
    						return;
     
    					}
     
    					json = JSON.parse( extensions[ EXTENSIONS.KHR_BINARY_GLTF ].content );
     
    				} else {
     
    					json = JSON.parse( THREE.LoaderUtils.decodeText( new Uint8Array( data ) ) );
     
    				}
     
    			} else {
     
    				json = data;
     
    			}
     
    			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_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_SHEEN: 'KHR_materials_sheen',
    		KHR_MATERIALS_SPECULAR: 'KHR_materials_specular',
    		KHR_MATERIALS_TRANSMISSION: 'KHR_materials_transmission',
    		KHR_MATERIALS_IRIDESCENCE: 'KHR_materials_iridescence',
    		KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
    		KHR_MATERIALS_VOLUME: 'KHR_materials_volume',
    		KHR_TEXTURE_BASISU: 'KHR_texture_basisu',
    		KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
    		KHR_MESH_QUANTIZATION: 'KHR_mesh_quantization',
    		KHR_MATERIALS_EMISSIVE_STRENGTH: 'KHR_materials_emissive_strength',
    		EXT_TEXTURE_WEBP: 'EXT_texture_webp',
    		EXT_MESHOPT_COMPRESSION: 'EXT_meshopt_compression',
    		EXT_MESH_GPU_INSTANCING: 'EXT_mesh_gpu_instancing'
    	};
     
    	/**
     * Punctual Lights Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
     */
    	class GLTFLightsExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;
     
    			// THREE.Object3D instance caches
    			this.cache = {
    				refs: {},
    				uses: {}
    			};
     
    		}
    		_markDefs() {
     
    			const parser = this.parser;
    			const nodeDefs = this.parser.json.nodes || [];
    			for ( let nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex ++ ) {
     
    				const nodeDef = nodeDefs[ nodeIndex ];
    				if ( nodeDef.extensions && nodeDef.extensions[ this.name ] && nodeDef.extensions[ this.name ].light !== undefined ) {
     
    					parser._addNodeRef( this.cache, nodeDef.extensions[ this.name ].light );
     
    				}
     
    			}
     
    		}
    		_loadLight( lightIndex ) {
     
    			const parser = this.parser;
    			const cacheKey = 'light:' + lightIndex;
    			let dependency = parser.cache.get( cacheKey );
    			if ( dependency ) return dependency;
    			const json = parser.json;
    			const extensions = json.extensions && json.extensions[ this.name ] || {};
    			const lightDefs = extensions.lights || [];
    			const lightDef = lightDefs[ lightIndex ];
    			let lightNode;
    			const color = new THREE.Color( 0xffffff );
    			if ( lightDef.color !== undefined ) color.fromArray( lightDef.color );
    			const range = lightDef.range !== undefined ? lightDef.range : 0;
    			switch ( lightDef.type ) {
     
    				case 'directional':
    					lightNode = new THREE.DirectionalLight( color );
    					lightNode.target.position.set( 0, 0, - 1 );
    					lightNode.add( lightNode.target );
    					break;
    				case 'point':
    					lightNode = new THREE.PointLight( color );
    					lightNode.distance = range;
    					break;
    				case 'spot':
    					lightNode = new THREE.SpotLight( color );
    					lightNode.distance = range;
    					// Handle spotlight properties.
    					lightDef.spot = lightDef.spot || {};
    					lightDef.spot.innerConeAngle = lightDef.spot.innerConeAngle !== undefined ? lightDef.spot.innerConeAngle : 0;
    					lightDef.spot.outerConeAngle = lightDef.spot.outerConeAngle !== undefined ? lightDef.spot.outerConeAngle : Math.PI / 4.0;
    					lightNode.angle = lightDef.spot.outerConeAngle;
    					lightNode.penumbra = 1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
    					lightNode.target.position.set( 0, 0, - 1 );
    					lightNode.add( lightNode.target );
    					break;
    				default:
    					throw new Error( 'THREE.GLTFLoader: Unexpected light type: ' + lightDef.type );
     
    			}
     
    			// Some lights (e.g. spot) default to a position other than the origin. Reset the position
    			// here, because node-level parsing will only override position if explicitly specified.
    			lightNode.position.set( 0, 0, 0 );
    			lightNode.decay = 2;
    			assignExtrasToUserData( lightNode, lightDef );
    			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;
     
    		}
    		getDependency( type, index ) {
     
    			if ( type !== 'light' ) return;
    			return this._loadLight( index );
     
    		}
    		createNodeAttachment( nodeIndex ) {
     
    			const self = this;
    			const parser = this.parser;
    			const json = parser.json;
    			const nodeDef = json.nodes[ nodeIndex ];
    			const lightDef = nodeDef.extensions && nodeDef.extensions[ this.name ] || {};
    			const lightIndex = lightDef.light;
    			if ( lightIndex === undefined ) return null;
    			return this._loadLight( lightIndex ).then( function ( light ) {
     
    				return parser._getNodeRef( self.cache, lightIndex, light );
     
    			} );
     
    		}
     
    	}
     
    	/**
     * Unlit Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
     */
    	class GLTFMaterialsUnlitExtension {
     
    		constructor() {
     
    			this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;
     
    		}
    		getMaterialType() {
     
    			return THREE.MeshBasicMaterial;
     
    		}
    		extendParams( materialParams, materialDef, parser ) {
     
    			const pending = [];
    			materialParams.color = new THREE.Color( 1.0, 1.0, 1.0 );
    			materialParams.opacity = 1.0;
    			const metallicRoughness = materialDef.pbrMetallicRoughness;
    			if ( metallicRoughness ) {
     
    				if ( Array.isArray( metallicRoughness.baseColorFactor ) ) {
     
    					const array = metallicRoughness.baseColorFactor;
    					materialParams.color.fromArray( array );
    					materialParams.opacity = array[ 3 ];
     
    				}
     
    				if ( metallicRoughness.baseColorTexture !== undefined ) {
     
    					pending.push( parser.assignTexture( materialParams, 'map', metallicRoughness.baseColorTexture, THREE.sRGBEncoding ) );
     
    				}
     
    			}
     
    			return Promise.all( pending );
     
    		}
     
    	}
     
    	/**
     * Materials Emissive Strength Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/blob/5768b3ce0ef32bc39cdf1bef10b948586635ead3/extensions/2.0/Khronos/KHR_materials_emissive_strength/README.md
     */
    	class GLTFMaterialsEmissiveStrengthExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_MATERIALS_EMISSIVE_STRENGTH;
     
    		}
    		extendMaterialParams( materialIndex, materialParams ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {
     
    				return Promise.resolve();
     
    			}
     
    			const emissiveStrength = materialDef.extensions[ this.name ].emissiveStrength;
    			if ( emissiveStrength !== undefined ) {
     
    				materialParams.emissiveIntensity = emissiveStrength;
     
    			}
     
    			return Promise.resolve();
     
    		}
     
    	}
     
    	/**
     * Clearcoat Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
     */
    	class GLTFMaterialsClearcoatExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;
     
    		}
    		getMaterialType( materialIndex ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
    			return THREE.MeshPhysicalMaterial;
     
    		}
    		extendMaterialParams( materialIndex, materialParams ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {
     
    				return Promise.resolve();
     
    			}
     
    			const pending = [];
    			const extension = materialDef.extensions[ this.name ];
    			if ( extension.clearcoatFactor !== undefined ) {
     
    				materialParams.clearcoat = extension.clearcoatFactor;
     
    			}
     
    			if ( extension.clearcoatTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'clearcoatMap', extension.clearcoatTexture ) );
     
    			}
     
    			if ( extension.clearcoatRoughnessFactor !== undefined ) {
     
    				materialParams.clearcoatRoughness = extension.clearcoatRoughnessFactor;
     
    			}
     
    			if ( extension.clearcoatRoughnessTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'clearcoatRoughnessMap', extension.clearcoatRoughnessTexture ) );
     
    			}
     
    			if ( extension.clearcoatNormalTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'clearcoatNormalMap', extension.clearcoatNormalTexture ) );
    				if ( extension.clearcoatNormalTexture.scale !== undefined ) {
     
    					const scale = extension.clearcoatNormalTexture.scale;
    					materialParams.clearcoatNormalScale = new THREE.Vector2( scale, scale );
     
    				}
     
    			}
     
    			return Promise.all( pending );
     
    		}
     
    	}
     
    	/**
     * Iridescence Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_iridescence
     */
    	class GLTFMaterialsIridescenceExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_MATERIALS_IRIDESCENCE;
     
    		}
    		getMaterialType( materialIndex ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
    			return THREE.MeshPhysicalMaterial;
     
    		}
    		extendMaterialParams( materialIndex, materialParams ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {
     
    				return Promise.resolve();
     
    			}
     
    			const pending = [];
    			const extension = materialDef.extensions[ this.name ];
    			if ( extension.iridescenceFactor !== undefined ) {
     
    				materialParams.iridescence = extension.iridescenceFactor;
     
    			}
     
    			if ( extension.iridescenceTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'iridescenceMap', extension.iridescenceTexture ) );
     
    			}
     
    			if ( extension.iridescenceIor !== undefined ) {
     
    				materialParams.iridescenceIOR = extension.iridescenceIor;
     
    			}
     
    			if ( materialParams.iridescenceThicknessRange === undefined ) {
     
    				materialParams.iridescenceThicknessRange = [ 100, 400 ];
     
    			}
     
    			if ( extension.iridescenceThicknessMinimum !== undefined ) {
     
    				materialParams.iridescenceThicknessRange[ 0 ] = extension.iridescenceThicknessMinimum;
     
    			}
     
    			if ( extension.iridescenceThicknessMaximum !== undefined ) {
     
    				materialParams.iridescenceThicknessRange[ 1 ] = extension.iridescenceThicknessMaximum;
     
    			}
     
    			if ( extension.iridescenceThicknessTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'iridescenceThicknessMap', extension.iridescenceThicknessTexture ) );
     
    			}
     
    			return Promise.all( pending );
     
    		}
     
    	}
     
    	/**
     * Sheen Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_sheen
     */
    	class GLTFMaterialsSheenExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_MATERIALS_SHEEN;
     
    		}
    		getMaterialType( materialIndex ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
    			return THREE.MeshPhysicalMaterial;
     
    		}
    		extendMaterialParams( materialIndex, materialParams ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {
     
    				return Promise.resolve();
     
    			}
     
    			const pending = [];
    			materialParams.sheenColor = new THREE.Color( 0, 0, 0 );
    			materialParams.sheenRoughness = 0;
    			materialParams.sheen = 1;
    			const extension = materialDef.extensions[ this.name ];
    			if ( extension.sheenColorFactor !== undefined ) {
     
    				materialParams.sheenColor.fromArray( extension.sheenColorFactor );
     
    			}
     
    			if ( extension.sheenRoughnessFactor !== undefined ) {
     
    				materialParams.sheenRoughness = extension.sheenRoughnessFactor;
     
    			}
     
    			if ( extension.sheenColorTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'sheenColorMap', extension.sheenColorTexture, THREE.sRGBEncoding ) );
     
    			}
     
    			if ( extension.sheenRoughnessTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'sheenRoughnessMap', extension.sheenRoughnessTexture ) );
     
    			}
     
    			return Promise.all( pending );
     
    		}
     
    	}
     
    	/**
     * Transmission Materials Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_transmission
     * Draft: https://github.com/KhronosGroup/glTF/pull/1698
     */
    	class GLTFMaterialsTransmissionExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_MATERIALS_TRANSMISSION;
     
    		}
    		getMaterialType( materialIndex ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
    			return THREE.MeshPhysicalMaterial;
     
    		}
    		extendMaterialParams( materialIndex, materialParams ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {
     
    				return Promise.resolve();
     
    			}
     
    			const pending = [];
    			const extension = materialDef.extensions[ this.name ];
    			if ( extension.transmissionFactor !== undefined ) {
     
    				materialParams.transmission = extension.transmissionFactor;
     
    			}
     
    			if ( extension.transmissionTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'transmissionMap', extension.transmissionTexture ) );
     
    			}
     
    			return Promise.all( pending );
     
    		}
     
    	}
     
    	/**
     * Materials Volume Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_volume
     */
    	class GLTFMaterialsVolumeExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_MATERIALS_VOLUME;
     
    		}
    		getMaterialType( materialIndex ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
    			return THREE.MeshPhysicalMaterial;
     
    		}
    		extendMaterialParams( materialIndex, materialParams ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {
     
    				return Promise.resolve();
     
    			}
     
    			const pending = [];
    			const extension = materialDef.extensions[ this.name ];
    			materialParams.thickness = extension.thicknessFactor !== undefined ? extension.thicknessFactor : 0;
    			if ( extension.thicknessTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'thicknessMap', extension.thicknessTexture ) );
     
    			}
     
    			materialParams.attenuationDistance = extension.attenuationDistance || Infinity;
    			const colorArray = extension.attenuationColor || [ 1, 1, 1 ];
    			materialParams.attenuationColor = new THREE.Color( colorArray[ 0 ], colorArray[ 1 ], colorArray[ 2 ] );
    			return Promise.all( pending );
     
    		}
     
    	}
     
    	/**
     * Materials ior Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_ior
     */
    	class GLTFMaterialsIorExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_MATERIALS_IOR;
     
    		}
    		getMaterialType( materialIndex ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
    			return THREE.MeshPhysicalMaterial;
     
    		}
    		extendMaterialParams( materialIndex, materialParams ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {
     
    				return Promise.resolve();
     
    			}
     
    			const extension = materialDef.extensions[ this.name ];
    			materialParams.ior = extension.ior !== undefined ? extension.ior : 1.5;
    			return Promise.resolve();
     
    		}
     
    	}
     
    	/**
     * Materials specular Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_specular
     */
    	class GLTFMaterialsSpecularExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_MATERIALS_SPECULAR;
     
    		}
    		getMaterialType( materialIndex ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
    			return THREE.MeshPhysicalMaterial;
     
    		}
    		extendMaterialParams( materialIndex, materialParams ) {
     
    			const parser = this.parser;
    			const materialDef = parser.json.materials[ materialIndex ];
    			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {
     
    				return Promise.resolve();
     
    			}
     
    			const pending = [];
    			const extension = materialDef.extensions[ this.name ];
    			materialParams.specularIntensity = extension.specularFactor !== undefined ? extension.specularFactor : 1.0;
    			if ( extension.specularTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'specularIntensityMap', extension.specularTexture ) );
     
    			}
     
    			const colorArray = extension.specularColorFactor || [ 1, 1, 1 ];
    			materialParams.specularColor = new THREE.Color( colorArray[ 0 ], colorArray[ 1 ], colorArray[ 2 ] );
    			if ( extension.specularColorTexture !== undefined ) {
     
    				pending.push( parser.assignTexture( materialParams, 'specularColorMap', extension.specularColorTexture, THREE.sRGBEncoding ) );
     
    			}
     
    			return Promise.all( pending );
     
    		}
     
    	}
     
    	/**
     * BasisU THREE.Texture Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu
     */
    	class GLTFTextureBasisUExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.KHR_TEXTURE_BASISU;
     
    		}
    		loadTexture( textureIndex ) {
     
    			const parser = this.parser;
    			const json = parser.json;
    			const textureDef = json.textures[ textureIndex ];
    			if ( ! textureDef.extensions || ! textureDef.extensions[ this.name ] ) {
     
    				return null;
     
    			}
     
    			const extension = textureDef.extensions[ this.name ];
    			const loader = parser.options.ktx2Loader;
    			if ( ! loader ) {
     
    				if ( json.extensionsRequired && json.extensionsRequired.indexOf( this.name ) >= 0 ) {
     
    					throw new Error( 'THREE.GLTFLoader: setKTX2Loader must be called before loading KTX2 textures' );
     
    				} else {
     
    					// Assumes that the extension is optional and that a fallback texture is present
    					return null;
     
    				}
     
    			}
     
    			return parser.loadTextureImage( textureIndex, extension.source, loader );
     
    		}
     
    	}
     
    	/**
     * WebP THREE.Texture Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_texture_webp
     */
    	class GLTFTextureWebPExtension {
     
    		constructor( parser ) {
     
    			this.parser = parser;
    			this.name = EXTENSIONS.EXT_TEXTURE_WEBP;
    			this.isSupported = null;
     
    		}
    		loadTexture( textureIndex ) {
     
    			const name = this.name;
    			const parser = this.parser;
    			const json = parser.json;
    			const textureDef = json.textures[ textureIndex ];
    			if ( ! textureDef.extensions || ! textureDef.extensions[ name ] ) {
     
    				return null;
     
    			}
     
    			const extension = textureDef.extensions[ name ];
    			const source = json.images[ extension.source ];
    			let loader = parser.textureLoader;
    			if ( source.uri ) {
     
    				const handler = parser.options.manager.getHandler( source.uri );
    				if ( handler !== null ) loader = handler;
     
    			}
     
    			return this.detectSupport().then( function ( isSupported ) {
     
    				if ( isSupported ) return parser.loadTextureImage( textureIndex, extension.source, loader );
    				if ( json.extensionsRequired && json.extensionsRequired.indexOf( name ) >= 0 ) {
     
    					throw new Error( 'THREE.GLTFLoader: WebP required by asset but unsupported.' );
     
    				}
     
    				// Fall back to PNG or JPEG.
    				return parser.loadTexture( textureIndex );
     
    			} );
     
    		}
    		detectSupport() {
     
    			if ( ! this.isSupported ) {
     
    				this.isSupported = new Promise( function ( resolve ) {
     
    					const image = new Image();
     
    					// Lossy test image. Support for lossy images doesn't guarantee support for all
    					// WebP images, unfortunately.
    					image.src = 'data:image/webp;base64,UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA';
    					image.onload = image.onerror = function () {
     
    						resolve( image.height === 1 );
     
    					};
     
    				} );
     
    			}
     
    			return this.isSupported;
     
    		}
     
    	}
     
    	/**
     * meshopt BufferView Compression Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_meshopt_compression
     */
    	class GLTFMeshoptCompression {
     
    		constructor( parser ) {
     
    			this.name = EXTENSIONS.EXT_MESHOPT_COMPRESSION;
    			this.parser = parser;
     
    		}
    		loadBufferView( index ) {
     
    			const json = this.parser.json;
    			const bufferView = json.bufferViews[ index ];
    			if ( bufferView.extensions && bufferView.extensions[ this.name ] ) {
     
    				const extensionDef = bufferView.extensions[ this.name ];
    				const buffer = this.parser.getDependency( 'buffer', extensionDef.buffer );
    				const decoder = this.parser.options.meshoptDecoder;
    				if ( ! decoder || ! decoder.supported ) {
     
    					if ( json.extensionsRequired && json.extensionsRequired.indexOf( this.name ) >= 0 ) {
     
    						throw new Error( 'THREE.GLTFLoader: setMeshoptDecoder must be called before loading compressed files' );
     
    					} else {
     
    						// Assumes that the extension is optional and that fallback buffer data is present
    						return null;
     
    					}
     
    				}
     
    				return buffer.then( function ( res ) {
     
    					const byteOffset = extensionDef.byteOffset || 0;
    					const byteLength = extensionDef.byteLength || 0;
    					const count = extensionDef.count;
    					const stride = extensionDef.byteStride;
    					const source = new Uint8Array( res, byteOffset, byteLength );
    					if ( decoder.decodeGltfBufferAsync ) {
     
    						return decoder.decodeGltfBufferAsync( count, stride, source, extensionDef.mode, extensionDef.filter ).then( function ( res ) {
     
    							return res.buffer;
     
    						} );
     
    					} else {
     
    						// Support for MeshoptDecoder 0.18 or earlier, without decodeGltfBufferAsync
    						return decoder.ready.then( function () {
     
    							const result = new ArrayBuffer( count * stride );
    							decoder.decodeGltfBuffer( new Uint8Array( result ), count, stride, source, extensionDef.mode, extensionDef.filter );
    							return result;
     
    						} );
     
    					}
     
    				} );
     
    			} else {
     
    				return null;
     
    			}
     
    		}
     
    	}
     
    	/**
     * GPU Instancing Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_mesh_gpu_instancing
     *
     */
    	class GLTFMeshGpuInstancing {
     
    		constructor( parser ) {
     
    			this.name = EXTENSIONS.EXT_MESH_GPU_INSTANCING;
    			this.parser = parser;
     
    		}
    		createNodeMesh( nodeIndex ) {
     
    			const json = this.parser.json;
    			const nodeDef = json.nodes[ nodeIndex ];
    			if ( ! nodeDef.extensions || ! nodeDef.extensions[ this.name ] || nodeDef.mesh === undefined ) {
     
    				return null;
     
    			}
     
    			const meshDef = json.meshes[ nodeDef.mesh ];
     
    			// No THREE.Points or Lines + Instancing support yet
     
    			for ( const primitive of meshDef.primitives ) {
     
    				if ( primitive.mode !== WEBGL_CONSTANTS.TRIANGLES && primitive.mode !== WEBGL_CONSTANTS.TRIANGLE_STRIP && primitive.mode !== WEBGL_CONSTANTS.TRIANGLE_FAN && primitive.mode !== undefined ) {
     
    					return null;
     
    				}
     
    			}
     
    			const extensionDef = nodeDef.extensions[ this.name ];
    			const attributesDef = extensionDef.attributes;
     
    			// @TODO: Can we support THREE.InstancedMesh + THREE.SkinnedMesh?
     
    			const pending = [];
    			const attributes = {};
    			for ( const key in attributesDef ) {
     
    				pending.push( this.parser.getDependency( 'accessor', attributesDef[ key ] ).then( accessor => {
     
    					attributes[ key ] = accessor;
    					return attributes[ key ];
     
    				} ) );
     
    			}
     
    			if ( pending.length < 1 ) {
     
    				return null;
     
    			}
     
    			pending.push( this.parser.createNodeMesh( nodeIndex ) );
    			return Promise.all( pending ).then( results => {
     
    				const nodeObject = results.pop();
    				const meshes = nodeObject.isGroup ? nodeObject.children : [ nodeObject ];
    				const count = results[ 0 ].count; // All attribute counts should be same
    				const instancedMeshes = [];
    				for ( const mesh of meshes ) {
     
    					// Temporal variables
    					const m = new THREE.Matrix4();
    					const p = new THREE.Vector3();
    					const q = new THREE.Quaternion();
    					const s = new THREE.Vector3( 1, 1, 1 );
    					const instancedMesh = new THREE.InstancedMesh( mesh.geometry, mesh.material, count );
    					for ( let i = 0; i < count; i ++ ) {
     
    						if ( attributes.TRANSLATION ) {
     
    							p.fromBufferAttribute( attributes.TRANSLATION, i );
     
    						}
     
    						if ( attributes.ROTATION ) {
     
    							q.fromBufferAttribute( attributes.ROTATION, i );
     
    						}
     
    						if ( attributes.SCALE ) {
     
    							s.fromBufferAttribute( attributes.SCALE, i );
     
    						}
     
    						instancedMesh.setMatrixAt( i, m.compose( p, q, s ) );
     
    					}
     
    					// Add instance attributes to the geometry, excluding TRS.
    					for ( const attributeName in attributes ) {
     
    						if ( attributeName !== 'TRANSLATION' && attributeName !== 'ROTATION' && attributeName !== 'SCALE' ) {
     
    							mesh.geometry.setAttribute( attributeName, attributes[ attributeName ] );
     
    						}
     
    					}
     
    					// Just in case
    					THREE.Object3D.prototype.copy.call( instancedMesh, mesh );
     
    					// https://github.com/mrdoob/three.js/issues/18334
    					instancedMesh.frustumCulled = false;
    					this.parser.assignFinalMaterial( instancedMesh );
    					instancedMeshes.push( instancedMesh );
     
    				}
     
    				if ( nodeObject.isGroup ) {
     
    					nodeObject.clear();
    					nodeObject.add( ...instancedMeshes );
    					return nodeObject;
     
    				}
     
    				return instancedMeshes[ 0 ];
     
    			} );
     
    		}
     
    	}
     
    	/* BINARY EXTENSION */
    	const BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
    	const BINARY_EXTENSION_HEADER_LENGTH = 12;
    	const BINARY_EXTENSION_CHUNK_TYPES = {
    		JSON: 0x4E4F534A,
    		BIN: 0x004E4942
    	};
    	class GLTFBinaryExtension {
     
    		constructor( data ) {
     
    			this.name = EXTENSIONS.KHR_BINARY_GLTF;
    			this.content = null;
    			this.body = null;
    			const headerView = new DataView( data, 0, BINARY_EXTENSION_HEADER_LENGTH );
    			this.header = {
    				magic: THREE.LoaderUtils.decodeText( new Uint8Array( data.slice( 0, 4 ) ) ),
    				version: headerView.getUint32( 4, true ),
    				length: headerView.getUint32( 8, true )
    			};
    			if ( this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC ) {
     
    				throw new Error( 'THREE.GLTFLoader: Unsupported glTF-Binary header.' );
     
    			} else if ( this.header.version < 2.0 ) {
     
    				throw new Error( 'THREE.GLTFLoader: Legacy binary file detected.' );
     
    			}
     
    			const chunkContentsLength = this.header.length - BINARY_EXTENSION_HEADER_LENGTH;
    			const chunkView = new DataView( data, BINARY_EXTENSION_HEADER_LENGTH );
    			let chunkIndex = 0;
    			while ( chunkIndex < chunkContentsLength ) {
     
    				const chunkLength = chunkView.getUint32( chunkIndex, true );
    				chunkIndex += 4;
    				const chunkType = chunkView.getUint32( chunkIndex, true );
    				chunkIndex += 4;
    				if ( chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON ) {
     
    					const contentArray = new Uint8Array( data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength );
    					this.content = THREE.LoaderUtils.decodeText( contentArray );
     
    				} else if ( chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN ) {
     
    					const byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
    					this.body = data.slice( byteOffset, byteOffset + chunkLength );
     
    				}
     
    				// Clients must ignore chunks with unknown types.
     
    				chunkIndex += chunkLength;
     
    			}
     
    			if ( this.content === null ) {
     
    				throw new Error( 'THREE.GLTFLoader: JSON content not found.' );
     
    			}
     
    		}
     
    	}
     
    	/**
     * DRACO THREE.Mesh Compression Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
     */
    	class GLTFDracoMeshCompressionExtension {
     
    		constructor( json, dracoLoader ) {
     
    			if ( ! dracoLoader ) {
     
    				throw new Error( 'THREE.GLTFLoader: No DRACOLoader instance provided.' );
     
    			}
     
    			this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
    			this.json = json;
    			this.dracoLoader = dracoLoader;
    			this.dracoLoader.preload();
     
    		}
    		decodePrimitive( primitive, parser ) {
     
    			const json = this.json;
    			const dracoLoader = this.dracoLoader;
    			const bufferViewIndex = primitive.extensions[ this.name ].bufferView;
    			const gltfAttributeMap = primitive.extensions[ this.name ].attributes;
    			const threeAttributeMap = {};
    			const attributeNormalizedMap = {};
    			const attributeTypeMap = {};
    			for ( const attributeName in gltfAttributeMap ) {
     
    				const threeAttributeName = ATTRIBUTES[ attributeName ] || attributeName.toLowerCase();
    				threeAttributeMap[ threeAttributeName ] = gltfAttributeMap[ attributeName ];
     
    			}
     
    			for ( const attributeName in primitive.attributes ) {
     
    				const threeAttributeName = ATTRIBUTES[ attributeName ] || attributeName.toLowerCase();
    				if ( gltfAttributeMap[ attributeName ] !== undefined ) {
     
    					const accessorDef = json.accessors[ primitive.attributes[ attributeName ] ];
    					const componentType = WEBGL_COMPONENT_TYPES[ accessorDef.componentType ];
    					attributeTypeMap[ threeAttributeName ] = componentType.name;
    					attributeNormalizedMap[ threeAttributeName ] = accessorDef.normalized === true;
     
    				}
     
    			}
     
    			return parser.getDependency( 'bufferView', bufferViewIndex ).then( function ( bufferView ) {
     
    				return new Promise( function ( resolve ) {
     
    					dracoLoader.decodeDracoFile( bufferView, function ( geometry ) {
     
    						for ( const attributeName in geometry.attributes ) {
     
    							const attribute = geometry.attributes[ attributeName ];
    							const normalized = attributeNormalizedMap[ attributeName ];
    							if ( normalized !== undefined ) attribute.normalized = normalized;
     
    						}
     
    						resolve( geometry );
     
    					}, threeAttributeMap, attributeTypeMap );
     
    				} );
     
    			} );
     
    		}
     
    	}
     
    	/**
     * THREE.Texture Transform Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
     */
    	class GLTFTextureTransformExtension {
     
    		constructor() {
     
    			this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;
     
    		}
    		extendTexture( texture, transform ) {
     
    			if ( transform.texCoord !== undefined ) {
     
    				console.warn( 'THREE.GLTFLoader: Custom UV sets in "' + this.name + '" extension not yet supported.' );
     
    			}
     
    			if ( transform.offset === undefined && transform.rotation === undefined && transform.scale === undefined ) {
     
    				// See https://github.com/mrdoob/three.js/issues/21819.
    				return texture;
     
    			}
     
    			texture = texture.clone();
    			if ( transform.offset !== undefined ) {
     
    				texture.offset.fromArray( transform.offset );
     
    			}
     
    			if ( transform.rotation !== undefined ) {
     
    				texture.rotation = transform.rotation;
     
    			}
     
    			if ( transform.scale !== undefined ) {
     
    				texture.repeat.fromArray( transform.scale );
     
    			}
     
    			texture.needsUpdate = true;
    			return texture;
     
    		}
     
    	}
     
    	/**
     * THREE.Mesh Quantization Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
     */
    	class GLTFMeshQuantizationExtension {
     
    		constructor() {
     
    			this.name = EXTENSIONS.KHR_MESH_QUANTIZATION;
     
    		}
     
    	}
     
    	/*********************************/
    	/********** INTERPOLATION ********/
    	/*********************************/
     
    	// Spline Interpolation
    	// Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
    	class GLTFCubicSplineInterpolant extends THREE.Interpolant {
     
    		constructor( parameterPositions, sampleValues, sampleSize, resultBuffer ) {
     
    			super( parameterPositions, sampleValues, sampleSize, resultBuffer );
     
    		}
    		copySampleValue_( index ) {
     
    			// Copies a sample value to the result buffer. See description of glTF
    			// CUBICSPLINE values layout in interpolate_() function below.
     
    			const result = this.resultBuffer,
    				values = this.sampleValues,
    				valueSize = this.valueSize,
    				offset = index * valueSize * 3 + valueSize;
    			for ( let i = 0; i !== valueSize; i ++ ) {
     
    				result[ i ] = values[ offset + i ];
     
    			}
     
    			return result;
     
    		}
    		interpolate_( i1, t0, t, t1 ) {
     
    			const result = this.resultBuffer;
    			const values = this.sampleValues;
    			const stride = this.valueSize;
    			const stride2 = stride * 2;
    			const stride3 = stride * 3;
    			const td = t1 - t0;
    			const p = ( t - t0 ) / td;
    			const pp = p * p;
    			const ppp = pp * p;
    			const offset1 = i1 * stride3;
    			const offset0 = offset1 - stride3;
    			const s2 = - 2 * ppp + 3 * pp;
    			const s3 = ppp - pp;
    			const s0 = 1 - s2;
    			const s1 = s3 - pp + p;
     
    			// Layout of keyframe output values for CUBICSPLINE animations:
    			//   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]
    			for ( let i = 0; i !== stride; i ++ ) {
     
    				const p0 = values[ offset0 + i + stride ]; // splineVertex_k
    				const m0 = values[ offset0 + i + stride2 ] * td; // outTangent_k * (t_k+1 - t_k)
    				const p1 = values[ offset1 + i + stride ]; // splineVertex_k+1
    				const m1 = values[ offset1 + i ] * td; // inTangent_k+1 * (t_k+1 - t_k)
     
    				result[ i ] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;
     
    			}
     
    			return result;
     
    		}
     
    	}
    	const _q = new THREE.Quaternion();
    	class GLTFCubicSplineQuaternionInterpolant extends GLTFCubicSplineInterpolant {
     
    		interpolate_( i1, t0, t, t1 ) {
     
    			const result = super.interpolate_( i1, t0, t, t1 );
    			_q.fromArray( result ).normalize().toArray( result );
    			return result;
     
    		}
     
    	}
     
    	/*********************************/
    	/********** INTERNALS ************/
    	/*********************************/
     
    	/* CONSTANTS */
     
    	const WEBGL_CONSTANTS = {
    		FLOAT: 5126,
    		//FLOAT_MAT2: 35674,
    		FLOAT_MAT3: 35675,
    		FLOAT_MAT4: 35676,
    		FLOAT_VEC2: 35664,
    		FLOAT_VEC3: 35665,
    		FLOAT_VEC4: 35666,
    		LINEAR: 9729,
    		REPEAT: 10497,
    		SAMPLER_2D: 35678,
    		POINTS: 0,
    		LINES: 1,
    		LINE_LOOP: 2,
    		LINE_STRIP: 3,
    		TRIANGLES: 4,
    		TRIANGLE_STRIP: 5,
    		TRIANGLE_FAN: 6,
    		UNSIGNED_BYTE: 5121,
    		UNSIGNED_SHORT: 5123
    	};
    	const WEBGL_COMPONENT_TYPES = {
    		5120: Int8Array,
    		5121: Uint8Array,
    		5122: Int16Array,
    		5123: Uint16Array,
    		5125: Uint32Array,
    		5126: Float32Array
    	};
    	const WEBGL_FILTERS = {
    		9728: THREE.NearestFilter,
    		9729: THREE.LinearFilter,
    		9984: THREE.NearestMipmapNearestFilter,
    		9985: THREE.LinearMipmapNearestFilter,
    		9986: THREE.NearestMipmapLinearFilter,
    		9987: THREE.LinearMipmapLinearFilter
    	};
    	const WEBGL_WRAPPINGS = {
    		33071: THREE.ClampToEdgeWrapping,
    		33648: THREE.MirroredRepeatWrapping,
    		10497: THREE.RepeatWrapping
    	};
    	const WEBGL_TYPE_SIZES = {
    		'SCALAR': 1,
    		'VEC2': 2,
    		'VEC3': 3,
    		'VEC4': 4,
    		'MAT2': 4,
    		'MAT3': 9,
    		'MAT4': 16
    	};
    	const ATTRIBUTES = {
    		POSITION: 'position',
    		NORMAL: 'normal',
    		TANGENT: 'tangent',
    		TEXCOORD_0: 'uv',
    		TEXCOORD_1: 'uv2',
    		COLOR_0: 'color',
    		WEIGHTS_0: 'skinWeight',
    		JOINTS_0: 'skinIndex'
    	};
    	const PATH_PROPERTIES = {
    		scale: 'scale',
    		translation: 'position',
    		rotation: 'quaternion',
    		weights: 'morphTargetInfluences'
    	};
    	const INTERPOLATION = {
    		CUBICSPLINE: undefined,
    		// We use a custom interpolant (GLTFCubicSplineInterpolation) for CUBICSPLINE tracks. Each
    		// keyframe track will be initialized with a default interpolation type, then modified.
    		LINEAR: THREE.InterpolateLinear,
    		STEP: THREE.InterpolateDiscrete
    	};
    	const ALPHA_MODES = {
    		OPAQUE: 'OPAQUE',
    		MASK: 'MASK',
    		BLEND: 'BLEND'
    	};
     
    	/**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
     */
    	function createDefaultMaterial( cache ) {
     
    		if ( cache[ 'DefaultMaterial' ] === undefined ) {
     
    			cache[ 'DefaultMaterial' ] = new THREE.MeshStandardMaterial( {
    				color: 0xFFFFFF,
    				emissive: 0x000000,
    				metalness: 1,
    				roughness: 1,
    				transparent: false,
    				depthTest: true,
    				side: THREE.FrontSide
    			} );
     
    		}
     
    		return cache[ 'DefaultMaterial' ];
     
    	}
     
    	function addUnknownExtensionsToUserData( knownExtensions, object, objectDef ) {
     
    		// Add unknown glTF extensions to an object's userData.
     
    		for ( const name in objectDef.extensions ) {
     
    			if ( knownExtensions[ name ] === undefined ) {
     
    				object.userData.gltfExtensions = object.userData.gltfExtensions || {};
    				object.userData.gltfExtensions[ name ] = objectDef.extensions[ name ];
     
    			}
     
    		}
     
    	}
     
    	/**
     * @param {Object3D|Material|BufferGeometry} object
     * @param {GLTF.definition} gltfDef
     */
    	function assignExtrasToUserData( object, gltfDef ) {
     
    		if ( gltfDef.extras !== undefined ) {
     
    			if ( typeof gltfDef.extras === 'object' ) {
     
    				Object.assign( object.userData, gltfDef.extras );
     
    			} else {
     
    				console.warn( 'THREE.GLTFLoader: Ignoring primitive type .extras, ' + gltfDef.extras );
     
    			}
     
    		}
     
    	}
     
    	/**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
     *
     * @param {BufferGeometry} geometry
     * @param {Array<GLTF.Target>} targets
     * @param {GLTFParser} parser
     * @return {Promise<BufferGeometry>}
     */
    	function addMorphTargets( geometry, targets, parser ) {
     
    		let hasMorphPosition = false;
    		let hasMorphNormal = false;
    		let hasMorphColor = false;
    		for ( let i = 0, il = targets.length; i < il; i ++ ) {
     
    			const target = targets[ i ];
    			if ( target.POSITION !== undefined ) hasMorphPosition = true;
    			if ( target.NORMAL !== undefined ) hasMorphNormal = true;
    			if ( target.COLOR_0 !== undefined ) hasMorphColor = true;
    			if ( hasMorphPosition && hasMorphNormal && hasMorphColor ) break;
     
    		}
     
    		if ( ! hasMorphPosition && ! hasMorphNormal && ! hasMorphColor ) return Promise.resolve( geometry );
    		const pendingPositionAccessors = [];
    		const pendingNormalAccessors = [];
    		const pendingColorAccessors = [];
    		for ( let i = 0, il = targets.length; i < il; i ++ ) {
     
    			const target = targets[ i ];
    			if ( hasMorphPosition ) {
     
    				const pendingAccessor = target.POSITION !== undefined ? parser.getDependency( 'accessor', target.POSITION ) : geometry.attributes.position;
    				pendingPositionAccessors.push( pendingAccessor );
     
    			}
     
    			if ( hasMorphNormal ) {
     
    				const pendingAccessor = target.NORMAL !== undefined ? parser.getDependency( 'accessor', target.NORMAL ) : geometry.attributes.normal;
    				pendingNormalAccessors.push( pendingAccessor );
     
    			}
     
    			if ( hasMorphColor ) {
     
    				const pendingAccessor = target.COLOR_0 !== undefined ? parser.getDependency( 'accessor', target.COLOR_0 ) : geometry.attributes.color;
    				pendingColorAccessors.push( pendingAccessor );
     
    			}
     
    		}
     
    		return Promise.all( [ Promise.all( pendingPositionAccessors ), Promise.all( pendingNormalAccessors ), Promise.all( pendingColorAccessors ) ] ).then( function ( accessors ) {
     
    			const morphPositions = accessors[ 0 ];
    			const morphNormals = accessors[ 1 ];
    			const morphColors = accessors[ 2 ];
    			if ( hasMorphPosition ) geometry.morphAttributes.position = morphPositions;
    			if ( hasMorphNormal ) geometry.morphAttributes.normal = morphNormals;
    			if ( hasMorphColor ) geometry.morphAttributes.color = morphColors;
    			geometry.morphTargetsRelative = true;
    			return geometry;
     
    		} );
     
    	}
     
    	/**
     * @param {Mesh} mesh
     * @param {GLTF.Mesh} meshDef
     */
    	function updateMorphTargets( mesh, meshDef ) {
     
    		mesh.updateMorphTargets();
    		if ( meshDef.weights !== undefined ) {
     
    			for ( let i = 0, il = meshDef.weights.length; i < il; i ++ ) {
     
    				mesh.morphTargetInfluences[ i ] = meshDef.weights[ i ];
     
    			}
     
    		}
     
    		// .extras has user-defined data, so check that .extras.targetNames is an array.
    		if ( meshDef.extras && Array.isArray( meshDef.extras.targetNames ) ) {
     
    			const targetNames = meshDef.extras.targetNames;
    			if ( mesh.morphTargetInfluences.length === targetNames.length ) {
     
    				mesh.morphTargetDictionary = {};
    				for ( let i = 0, il = targetNames.length; i < il; i ++ ) {
     
    					mesh.morphTargetDictionary[ targetNames[ i ] ] = i;
     
    				}
     
    			} else {
     
    				console.warn( 'THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names.' );
     
    			}
     
    		}
     
    	}
     
    	function createPrimitiveKey( primitiveDef ) {
     
    		const dracoExtension = primitiveDef.extensions && primitiveDef.extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ];
    		let geometryKey;
    		if ( dracoExtension ) {
     
    			geometryKey = 'draco:' + dracoExtension.bufferView + ':' + dracoExtension.indices + ':' + createAttributesKey( dracoExtension.attributes );
     
    		} else {
     
    			geometryKey = primitiveDef.indices + ':' + createAttributesKey( primitiveDef.attributes ) + ':' + primitiveDef.mode;
     
    		}
     
    		return geometryKey;
     
    	}
     
    	function createAttributesKey( attributes ) {
     
    		let attributesKey = '';
    		const keys = Object.keys( attributes ).sort();
    		for ( let i = 0, il = keys.length; i < il; i ++ ) {
     
    			attributesKey += keys[ i ] + ':' + attributes[ keys[ i ] ] + ';';
     
    		}
     
    		return attributesKey;
     
    	}
     
    	function getNormalizedComponentScale( constructor ) {
     
    		// Reference:
    		// https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization#encoding-quantized-data
     
    		switch ( constructor ) {
     
    			case Int8Array:
    				return 1 / 127;
    			case Uint8Array:
    				return 1 / 255;
    			case Int16Array:
    				return 1 / 32767;
    			case Uint16Array:
    				return 1 / 65535;
    			default:
    				throw new Error( 'THREE.GLTFLoader: Unsupported normalized accessor component type.' );
     
    		}
     
    	}
     
    	function getImageURIMimeType( uri ) {
     
    		if ( uri.search( /\.jpe?g($|\?)/i ) > 0 || uri.search( /^data\:image\/jpeg/ ) === 0 ) return 'image/jpeg';
    		if ( uri.search( /\.webp($|\?)/i ) > 0 || uri.search( /^data\:image\/webp/ ) === 0 ) return 'image/webp';
    		return 'image/png';
     
    	}
     
    	/* GLTF PARSER */
     
    	class GLTFParser {
     
    		constructor( json = {}, options = {} ) {
     
    			this.json = json;
    			this.extensions = {};
    			this.plugins = {};
    			this.options = options;
     
    			// loader object cache
    			this.cache = new GLTFRegistry();
     
    			// associations between Three.js objects and glTF elements
    			this.associations = new Map();
     
    			// THREE.BufferGeometry caching
    			this.primitiveCache = {};
     
    			// THREE.Object3D instance caches
    			this.meshCache = {
    				refs: {},
    				uses: {}
    			};
    			this.cameraCache = {
    				refs: {},
    				uses: {}
    			};
    			this.lightCache = {
    				refs: {},
    				uses: {}
    			};
    			this.sourceCache = {};
    			this.textureCache = {};
     
    			// Track node names, to ensure no duplicates
    			this.nodeNamesUsed = {};
     
    			// Use an THREE.ImageBitmapLoader if imageBitmaps are supported. Moves much of the
    			// expensive work of uploading a texture to the GPU off the main thread.
     
    			let isSafari = false;
    			let isFirefox = false;
    			let firefoxVersion = - 1;
    			if ( typeof navigator !== 'undefined' ) {
     
    				isSafari = /^((?!chrome|android).)*safari/i.test( navigator.userAgent ) === true;
    				isFirefox = navigator.userAgent.indexOf( 'Firefox' ) > - 1;
    				firefoxVersion = isFirefox ? navigator.userAgent.match( /Firefox\/([0-9]+)\./ )[ 1 ] : - 1;
     
    			}
     
    			if ( typeof createImageBitmap === 'undefined' || isSafari || isFirefox && firefoxVersion < 98 ) {
     
    				this.textureLoader = new THREE.TextureLoader( this.options.manager );
     
    			} else {
     
    				this.textureLoader = new THREE.ImageBitmapLoader( this.options.manager );
     
    			}
     
    			this.textureLoader.setCrossOrigin( this.options.crossOrigin );
    			this.textureLoader.setRequestHeader( this.options.requestHeader );
    			this.fileLoader = new THREE.FileLoader( this.options.manager );
    			this.fileLoader.setResponseType( 'arraybuffer' );
    			if ( this.options.crossOrigin === 'use-credentials' ) {
     
    				this.fileLoader.setWithCredentials( true );
     
    			}
     
    		}
    		setExtensions( extensions ) {
     
    			this.extensions = extensions;
     
    		}
    		setPlugins( plugins ) {
     
    			this.plugins = plugins;
     
    		}
    		parse( onLoad, onError ) {
     
    			const parser = this;
    			const json = this.json;
    			const extensions = this.extensions;
     
    			// Clear the loader cache
    			this.cache.removeAll();
     
    			// Mark the special nodes/meshes in json for efficient parse
    			this._invokeAll( function ( ext ) {
     
    				return ext._markDefs && ext._markDefs();
     
    			} );
    			Promise.all( this._invokeAll( function ( ext ) {
     
    				return ext.beforeRoot && ext.beforeRoot();
     
    			} ) ).then( function () {
     
    				return Promise.all( [ parser.getDependencies( 'scene' ), parser.getDependencies( 'animation' ), parser.getDependencies( 'camera' ) ] );
     
    			} ).then( function ( dependencies ) {
     
    				const result = {
    					scene: dependencies[ 0 ][ json.scene || 0 ],
    					scenes: dependencies[ 0 ],
    					animations: dependencies[ 1 ],
    					cameras: dependencies[ 2 ],
    					asset: json.asset,
    					parser: parser,
    					userData: {}
    				};
    				addUnknownExtensionsToUserData( extensions, result, json );
    				assignExtrasToUserData( result, json );
    				Promise.all( parser._invokeAll( function ( ext ) {
     
    					return ext.afterRoot && ext.afterRoot( result );
     
    				} ) ).then( function () {
     
    					onLoad( result );
     
    				} );
     
    			} ).catch( onError );
     
    		}
     
    		/**
       * Marks the special nodes/meshes in json for efficient parse.
       */
    		_markDefs() {
     
    			const nodeDefs = this.json.nodes || [];
    			const skinDefs = this.json.skins || [];
    			const meshDefs = this.json.meshes || [];
     
    			// Nothing in the node definition indicates whether it is a THREE.Bone or an
    			// THREE.Object3D. Use the skins' joint references to mark bones.
    			for ( let skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex ++ ) {
     
    				const joints = skinDefs[ skinIndex ].joints;
    				for ( let i = 0, il = joints.length; i < il; i ++ ) {
     
    					nodeDefs[ joints[ i ] ].isBone = true;
     
    				}
     
    			}
     
    			// Iterate over all nodes, marking references to shared resources,
    			// as well as skeleton joints.
    			for ( let nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex ++ ) {
     
    				const nodeDef = nodeDefs[ nodeIndex ];
    				if ( nodeDef.mesh !== undefined ) {
     
    					this._addNodeRef( this.meshCache, nodeDef.mesh );
     
    					// Nothing in the mesh definition indicates whether it is
    					// a THREE.SkinnedMesh or THREE.Mesh. Use the node's mesh reference
    					// to mark THREE.SkinnedMesh if node has skin.
    					if ( nodeDef.skin !== undefined ) {
     
    						meshDefs[ nodeDef.mesh ].isSkinnedMesh = true;
     
    					}
     
    				}
     
    				if ( nodeDef.camera !== undefined ) {
     
    					this._addNodeRef( this.cameraCache, nodeDef.camera );
     
    				}
     
    			}
     
    		}
     
    		/**
       * Counts references to shared node / THREE.Object3D resources. These resources
       * can be reused, or "instantiated", at multiple nodes in the scene
       * hierarchy. THREE.Mesh, Camera, and Light instances are instantiated and must
       * be marked. Non-scenegraph resources (like Materials, Geometries, and
       * Textures) can be reused directly and are not marked here.
       *
       * Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
       */
    		_addNodeRef( cache, index ) {
     
    			if ( index === undefined ) return;
    			if ( cache.refs[ index ] === undefined ) {
     
    				cache.refs[ index ] = cache.uses[ index ] = 0;
     
    			}
     
    			cache.refs[ index ] ++;
     
    		}
     
    		/** Returns a reference to a shared resource, cloning it if necessary. */
    		_getNodeRef( cache, index, object ) {
     
    			if ( cache.refs[ index ] <= 1 ) return object;
    			const ref = object.clone();
     
    			// Propagates mappings to the cloned object, prevents mappings on the
    			// original object from being lost.
    			const updateMappings = ( original, clone ) => {
     
    				const mappings = this.associations.get( original );
    				if ( mappings != null ) {
     
    					this.associations.set( clone, mappings );
     
    				}
     
    				for ( const [ i, child ] of original.children.entries() ) {
     
    					updateMappings( child, clone.children[ i ] );
     
    				}
     
    			};
     
    			updateMappings( object, ref );
    			ref.name += '_instance_' + cache.uses[ index ] ++;
    			return ref;
     
    		}
    		_invokeOne( func ) {
     
    			const extensions = Object.values( this.plugins );
    			extensions.push( this );
    			for ( let i = 0; i < extensions.length; i ++ ) {
     
    				const result = func( extensions[ i ] );
    				if ( result ) return result;
     
    			}
     
    			return null;
     
    		}
    		_invokeAll( func ) {
     
    			const extensions = Object.values( this.plugins );
    			extensions.unshift( this );
    			const pending = [];
    			for ( let i = 0; i < extensions.length; i ++ ) {
     
    				const result = func( extensions[ i ] );
    				if ( result ) pending.push( result );
     
    			}
     
    			return pending;
     
    		}
     
    		/**
       * Requests the specified dependency asynchronously, with caching.
       * @param {string} type
       * @param {number} index
       * @return {Promise<Object3D|Material|THREE.Texture|AnimationClip|ArrayBuffer|Object>}
       */
    		getDependency( type, index ) {
     
    			const cacheKey = type + ':' + index;
    			let dependency = this.cache.get( cacheKey );
    			if ( ! dependency ) {
     
    				switch ( type ) {
     
    					case 'scene':
    						dependency = this.loadScene( index );
    						break;
    					case 'node':
    						dependency = this.loadNode( index );
    						break;
    					case 'mesh':
    						dependency = this._invokeOne( function ( ext ) {
     
    							return ext.loadMesh && ext.loadMesh( index );
     
    						} );
    						break;
    					case 'accessor':
    						dependency = this.loadAccessor( index );
    						break;
    					case 'bufferView':
    						dependency = this._invokeOne( function ( ext ) {
     
    							return ext.loadBufferView && ext.loadBufferView( index );
     
    						} );
    						break;
    					case 'buffer':
    						dependency = this.loadBuffer( index );
    						break;
    					case 'material':
    						dependency = this._invokeOne( function ( ext ) {
     
    							return ext.loadMaterial && ext.loadMaterial( index );
     
    						} );
    						break;
    					case 'texture':
    						dependency = this._invokeOne( function ( ext ) {
     
    							return ext.loadTexture && ext.loadTexture( index );
     
    						} );
    						break;
    					case 'skin':
    						dependency = this.loadSkin( index );
    						break;
    					case 'animation':
    						dependency = this._invokeOne( function ( ext ) {
     
    							return ext.loadAnimation && ext.loadAnimation( index );
     
    						} );
    						break;
    					case 'camera':
    						dependency = this.loadCamera( index );
    						break;
    					default:
    						dependency = this._invokeOne( function ( ext ) {
     
    							return ext != this && ext.getDependency && ext.getDependency( type, index );
     
    						} );
    						if ( ! dependency ) {
     
    							throw new Error( 'Unknown type: ' + type );
     
    						}
     
    						break;
     
    				}
     
    				this.cache.add( cacheKey, dependency );
     
    			}
     
    			return dependency;
     
    		}
     
    		/**
       * Requests all dependencies of the specified type asynchronously, with caching.
       * @param {string} type
       * @return {Promise<Array<Object>>}
       */
    		getDependencies( type ) {
     
    			let dependencies = this.cache.get( type );
    			if ( ! dependencies ) {
     
    				const parser = this;
    				const defs = this.json[ type + ( type === 'mesh' ? 'es' : 's' ) ] || [];
    				dependencies = Promise.all( defs.map( function ( def, index ) {
     
    					return parser.getDependency( type, index );
     
    				} ) );
    				this.cache.add( type, dependencies );
     
    			}
     
    			return dependencies;
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
       * @param {number} bufferIndex
       * @return {Promise<ArrayBuffer>}
       */
    		loadBuffer( bufferIndex ) {
     
    			const bufferDef = this.json.buffers[ bufferIndex ];
    			const loader = this.fileLoader;
    			if ( bufferDef.type && bufferDef.type !== 'arraybuffer' ) {
     
    				throw new Error( 'THREE.GLTFLoader: ' + bufferDef.type + ' buffer type is not supported.' );
     
    			}
     
    			// If present, GLB container is required to be the first buffer.
    			if ( bufferDef.uri === undefined && bufferIndex === 0 ) {
     
    				return Promise.resolve( this.extensions[ EXTENSIONS.KHR_BINARY_GLTF ].body );
     
    			}
     
    			const options = this.options;
    			return new Promise( function ( resolve, reject ) {
     
    				loader.load( THREE.LoaderUtils.resolveURL( bufferDef.uri, options.path ), resolve, undefined, function () {
     
    					reject( new Error( 'THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".' ) );
     
    				} );
     
    			} );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
       * @param {number} bufferViewIndex
       * @return {Promise<ArrayBuffer>}
       */
    		loadBufferView( bufferViewIndex ) {
     
    			const bufferViewDef = this.json.bufferViews[ bufferViewIndex ];
    			return this.getDependency( 'buffer', bufferViewDef.buffer ).then( function ( buffer ) {
     
    				const byteLength = bufferViewDef.byteLength || 0;
    				const byteOffset = bufferViewDef.byteOffset || 0;
    				return buffer.slice( byteOffset, byteOffset + byteLength );
     
    			} );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
       * @param {number} accessorIndex
       * @return {Promise<BufferAttribute|InterleavedBufferAttribute>}
       */
    		loadAccessor( accessorIndex ) {
     
    			const parser = this;
    			const json = this.json;
    			const accessorDef = this.json.accessors[ accessorIndex ];
    			if ( accessorDef.bufferView === undefined && accessorDef.sparse === undefined ) {
     
    				const itemSize = WEBGL_TYPE_SIZES[ accessorDef.type ];
    				const TypedArray = WEBGL_COMPONENT_TYPES[ accessorDef.componentType ];
    				const normalized = accessorDef.normalized === true;
    				const array = new TypedArray( accessorDef.count * itemSize );
    				return Promise.resolve( new THREE.BufferAttribute( array, itemSize, normalized ) );
     
    			}
     
    			const pendingBufferViews = [];
    			if ( accessorDef.bufferView !== undefined ) {
     
    				pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.bufferView ) );
     
    			} else {
     
    				pendingBufferViews.push( null );
     
    			}
     
    			if ( accessorDef.sparse !== undefined ) {
     
    				pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.sparse.indices.bufferView ) );
    				pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.sparse.values.bufferView ) );
     
    			}
     
    			return Promise.all( pendingBufferViews ).then( function ( bufferViews ) {
     
    				const bufferView = bufferViews[ 0 ];
    				const itemSize = WEBGL_TYPE_SIZES[ accessorDef.type ];
    				const TypedArray = WEBGL_COMPONENT_TYPES[ accessorDef.componentType ];
     
    				// For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.
    				const elementBytes = TypedArray.BYTES_PER_ELEMENT;
    				const itemBytes = elementBytes * itemSize;
    				const byteOffset = accessorDef.byteOffset || 0;
    				const byteStride = accessorDef.bufferView !== undefined ? json.bufferViews[ accessorDef.bufferView ].byteStride : undefined;
    				const normalized = accessorDef.normalized === true;
    				let array, bufferAttribute;
     
    				// The buffer is not interleaved if the stride is the item size in bytes.
    				if ( byteStride && byteStride !== itemBytes ) {
     
    					// Each "slice" of the buffer, as defined by 'count' elements of 'byteStride' bytes, gets its own THREE.InterleavedBuffer
    					// This makes sure that IBA.count reflects accessor.count properly
    					const ibSlice = Math.floor( byteOffset / byteStride );
    					const ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType + ':' + ibSlice + ':' + accessorDef.count;
    					let ib = parser.cache.get( ibCacheKey );
    					if ( ! ib ) {
     
    						array = new TypedArray( bufferView, ibSlice * byteStride, accessorDef.count * byteStride / elementBytes );
     
    						// Integer parameters to IB/IBA are in array elements, not bytes.
    						ib = new THREE.InterleavedBuffer( array, byteStride / elementBytes );
    						parser.cache.add( ibCacheKey, ib );
     
    					}
     
    					bufferAttribute = new THREE.InterleavedBufferAttribute( ib, itemSize, byteOffset % byteStride / elementBytes, normalized );
     
    				} else {
     
    					if ( bufferView === null ) {
     
    						array = new TypedArray( accessorDef.count * itemSize );
     
    					} else {
     
    						array = new TypedArray( bufferView, byteOffset, accessorDef.count * itemSize );
     
    					}
     
    					bufferAttribute = new THREE.BufferAttribute( array, itemSize, normalized );
     
    				}
     
    				// https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
    				if ( accessorDef.sparse !== undefined ) {
     
    					const itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
    					const TypedArrayIndices = WEBGL_COMPONENT_TYPES[ accessorDef.sparse.indices.componentType ];
    					const byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
    					const byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;
    					const sparseIndices = new TypedArrayIndices( bufferViews[ 1 ], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices );
    					const sparseValues = new TypedArray( bufferViews[ 2 ], byteOffsetValues, accessorDef.sparse.count * itemSize );
    					if ( bufferView !== null ) {
     
    						// Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
    						bufferAttribute = new THREE.BufferAttribute( bufferAttribute.array.slice(), bufferAttribute.itemSize, bufferAttribute.normalized );
     
    					}
     
    					for ( let i = 0, il = sparseIndices.length; i < il; i ++ ) {
     
    						const index = sparseIndices[ i ];
    						bufferAttribute.setX( index, sparseValues[ i * itemSize ] );
    						if ( itemSize >= 2 ) bufferAttribute.setY( index, sparseValues[ i * itemSize + 1 ] );
    						if ( itemSize >= 3 ) bufferAttribute.setZ( index, sparseValues[ i * itemSize + 2 ] );
    						if ( itemSize >= 4 ) bufferAttribute.setW( index, sparseValues[ i * itemSize + 3 ] );
    						if ( itemSize >= 5 ) throw new Error( 'THREE.GLTFLoader: Unsupported itemSize in sparse THREE.BufferAttribute.' );
     
    					}
     
    				}
     
    				return bufferAttribute;
     
    			} );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
       * @param {number} textureIndex
       * @return {Promise<THREE.Texture|null>}
       */
    		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;
    				texture.name = textureDef.name || sourceDef.name || '';
    				const samplers = json.samplers || {};
    				const sampler = samplers[ textureDef.sampler ] || {};
    				texture.magFilter = WEBGL_FILTERS[ sampler.magFilter ] || THREE.LinearFilter;
    				texture.minFilter = WEBGL_FILTERS[ sampler.minFilter ] || THREE.LinearMipmapLinearFilter;
    				texture.wrapS = WEBGL_WRAPPINGS[ sampler.wrapS ] || THREE.RepeatWrapping;
    				texture.wrapT = WEBGL_WRAPPINGS[ sampler.wrapT ] || THREE.RepeatWrapping;
    				parser.associations.set( texture, {
    					textures: textureIndex
    				} );
    				return texture;
     
    			} ).catch( function () {
     
    				return null;
     
    			} );
    			this.textureCache[ cacheKey ] = promise;
    			return promise;
     
    		}
    		loadImageSource( sourceIndex, loader ) {
     
    			const parser = this;
    			const json = this.json;
    			const options = this.options;
    			if ( this.sourceCache[ sourceIndex ] !== undefined ) {
     
    				return this.sourceCache[ sourceIndex ].then( texture => texture.clone() );
     
    			}
     
    			const sourceDef = json.images[ sourceIndex ];
    			const URL = self.URL || self.webkitURL;
    			let sourceURI = sourceDef.uri || '';
    			let isObjectURL = false;
    			if ( sourceDef.bufferView !== undefined ) {
     
    				// Load binary image data from bufferView, if provided.
     
    				sourceURI = parser.getDependency( 'bufferView', sourceDef.bufferView ).then( function ( bufferView ) {
     
    					isObjectURL = true;
    					const blob = new Blob( [ bufferView ], {
    						type: sourceDef.mimeType
    					} );
    					sourceURI = URL.createObjectURL( blob );
    					return sourceURI;
     
    				} );
     
    			} else if ( sourceDef.uri === undefined ) {
     
    				throw new Error( 'THREE.GLTFLoader: Image ' + sourceIndex + ' is missing URI and bufferView' );
     
    			}
     
    			const promise = Promise.resolve( sourceURI ).then( function ( sourceURI ) {
     
    				return new Promise( function ( resolve, reject ) {
     
    					let onLoad = resolve;
    					if ( loader.isImageBitmapLoader === true ) {
     
    						onLoad = function ( imageBitmap ) {
     
    							const texture = new THREE.Texture( imageBitmap );
    							texture.needsUpdate = true;
    							resolve( texture );
     
    						};
     
    					}
     
    					loader.load( THREE.LoaderUtils.resolveURL( sourceURI, options.path ), onLoad, undefined, reject );
     
    				} );
     
    			} ).then( function ( texture ) {
     
    				// Clean up resources and configure THREE.Texture.
     
    				if ( isObjectURL === true ) {
     
    					URL.revokeObjectURL( sourceURI );
     
    				}
     
    				texture.userData.mimeType = sourceDef.mimeType || getImageURIMimeType( sourceDef.uri );
    				return texture;
     
    			} ).catch( function ( error ) {
     
    				console.error( 'THREE.GLTFLoader: Couldn\'t load texture', sourceURI );
    				throw error;
     
    			} );
    			this.sourceCache[ sourceIndex ] = promise;
    			return promise;
     
    		}
     
    		/**
       * Asynchronously assigns a texture to the given material parameters.
       * @param {Object} materialParams
       * @param {string} mapName
       * @param {Object} mapDef
       * @return {Promise<Texture>}
       */
    		assignTexture( materialParams, mapName, mapDef, encoding ) {
     
    			const parser = this;
    			return this.getDependency( 'texture', mapDef.index ).then( function ( texture ) {
     
    				if ( ! texture ) return null;
     
    				// Materials sample aoMap from UV set 1 and other maps from UV set 0 - this can't be configured
    				// However, we will copy UV set 0 to UV set 1 on demand for aoMap
    				if ( mapDef.texCoord !== undefined && mapDef.texCoord != 0 && ! ( mapName === 'aoMap' && mapDef.texCoord == 1 ) ) {
     
    					console.warn( 'THREE.GLTFLoader: Custom UV set ' + mapDef.texCoord + ' for texture ' + mapName + ' not yet supported.' );
     
    				}
     
    				if ( parser.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ] ) {
     
    					const transform = mapDef.extensions !== undefined ? mapDef.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ] : undefined;
    					if ( transform ) {
     
    						const gltfReference = parser.associations.get( texture );
    						texture = parser.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ].extendTexture( texture, transform );
    						parser.associations.set( texture, gltfReference );
     
    					}
     
    				}
     
    				if ( encoding !== undefined ) {
     
    					texture.encoding = encoding;
     
    				}
     
    				materialParams[ mapName ] = texture;
    				return texture;
     
    			} );
     
    		}
     
    		/**
       * Assigns final material to a THREE.Mesh, THREE.Line, or THREE.Points instance. The instance
       * already has a material (generated from the glTF material options alone)
       * but reuse of the same glTF material may require multiple threejs materials
       * to accommodate different primitive types, defines, etc. New materials will
       * be created if necessary, and reused from a cache.
       * @param  {Object3D} mesh THREE.Mesh, THREE.Line, or THREE.Points instance.
       */
    		assignFinalMaterial( mesh ) {
     
    			const geometry = mesh.geometry;
    			let material = mesh.material;
    			const useDerivativeTangents = geometry.attributes.tangent === undefined;
    			const useVertexColors = geometry.attributes.color !== undefined;
    			const useFlatShading = geometry.attributes.normal === undefined;
    			if ( mesh.isPoints ) {
     
    				const cacheKey = 'PointsMaterial:' + material.uuid;
    				let pointsMaterial = this.cache.get( cacheKey );
    				if ( ! pointsMaterial ) {
     
    					pointsMaterial = new THREE.PointsMaterial();
    					THREE.Material.prototype.copy.call( pointsMaterial, material );
    					pointsMaterial.color.copy( material.color );
    					pointsMaterial.map = material.map;
    					pointsMaterial.sizeAttenuation = false; // glTF spec says points should be 1px
     
    					this.cache.add( cacheKey, pointsMaterial );
     
    				}
     
    				material = pointsMaterial;
     
    			} else if ( mesh.isLine ) {
     
    				const cacheKey = 'LineBasicMaterial:' + material.uuid;
    				let lineMaterial = this.cache.get( cacheKey );
    				if ( ! lineMaterial ) {
     
    					lineMaterial = new THREE.LineBasicMaterial();
    					THREE.Material.prototype.copy.call( lineMaterial, material );
    					lineMaterial.color.copy( material.color );
    					this.cache.add( cacheKey, lineMaterial );
     
    				}
     
    				material = lineMaterial;
     
    			}
     
    			// Clone the material if it will be modified
    			if ( useDerivativeTangents || useVertexColors || useFlatShading ) {
     
    				let cacheKey = 'ClonedMaterial:' + material.uuid + ':';
    				if ( useDerivativeTangents ) cacheKey += 'derivative-tangents:';
    				if ( useVertexColors ) cacheKey += 'vertex-colors:';
    				if ( useFlatShading ) cacheKey += 'flat-shading:';
    				let cachedMaterial = this.cache.get( cacheKey );
    				if ( ! cachedMaterial ) {
     
    					cachedMaterial = material.clone();
    					if ( useVertexColors ) cachedMaterial.vertexColors = true;
    					if ( useFlatShading ) cachedMaterial.flatShading = true;
    					if ( useDerivativeTangents ) {
     
    						// https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
    						if ( cachedMaterial.normalScale ) cachedMaterial.normalScale.y *= - 1;
    						if ( cachedMaterial.clearcoatNormalScale ) cachedMaterial.clearcoatNormalScale.y *= - 1;
     
    					}
     
    					this.cache.add( cacheKey, cachedMaterial );
    					this.associations.set( cachedMaterial, this.associations.get( material ) );
     
    				}
     
    				material = cachedMaterial;
     
    			}
     
    			// workarounds for mesh and geometry
     
    			if ( material.aoMap && geometry.attributes.uv2 === undefined && geometry.attributes.uv !== undefined ) {
     
    				geometry.setAttribute( 'uv2', geometry.attributes.uv );
     
    			}
     
    			mesh.material = material;
     
    		}
    		getMaterialType() {
     
    			return THREE.MeshStandardMaterial;
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
       * @param {number} materialIndex
       * @return {Promise<Material>}
       */
    		loadMaterial( materialIndex ) {
     
    			const parser = this;
    			const json = this.json;
    			const extensions = this.extensions;
    			const materialDef = json.materials[ materialIndex ];
    			let materialType;
    			const materialParams = {};
    			const materialExtensions = materialDef.extensions || {};
    			const pending = [];
    			if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_UNLIT ] ) {
     
    				const kmuExtension = extensions[ EXTENSIONS.KHR_MATERIALS_UNLIT ];
    				materialType = kmuExtension.getMaterialType();
    				pending.push( kmuExtension.extendParams( materialParams, materialDef, parser ) );
     
    			} else {
     
    				// Specification:
    				// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material
     
    				const metallicRoughness = materialDef.pbrMetallicRoughness || {};
    				materialParams.color = new THREE.Color( 1.0, 1.0, 1.0 );
    				materialParams.opacity = 1.0;
    				if ( Array.isArray( metallicRoughness.baseColorFactor ) ) {
     
    					const array = metallicRoughness.baseColorFactor;
    					materialParams.color.fromArray( array );
    					materialParams.opacity = array[ 3 ];
     
    				}
     
    				if ( metallicRoughness.baseColorTexture !== undefined ) {
     
    					pending.push( parser.assignTexture( materialParams, 'map', metallicRoughness.baseColorTexture, THREE.sRGBEncoding ) );
     
    				}
     
    				materialParams.metalness = metallicRoughness.metallicFactor !== undefined ? metallicRoughness.metallicFactor : 1.0;
    				materialParams.roughness = metallicRoughness.roughnessFactor !== undefined ? metallicRoughness.roughnessFactor : 1.0;
    				if ( metallicRoughness.metallicRoughnessTexture !== undefined ) {
     
    					pending.push( parser.assignTexture( materialParams, 'metalnessMap', metallicRoughness.metallicRoughnessTexture ) );
    					pending.push( parser.assignTexture( materialParams, 'roughnessMap', metallicRoughness.metallicRoughnessTexture ) );
     
    				}
     
    				materialType = this._invokeOne( function ( ext ) {
     
    					return ext.getMaterialType && ext.getMaterialType( materialIndex );
     
    				} );
    				pending.push( Promise.all( this._invokeAll( function ( ext ) {
     
    					return ext.extendMaterialParams && ext.extendMaterialParams( materialIndex, materialParams );
     
    				} ) ) );
     
    			}
     
    			if ( materialDef.doubleSided === true ) {
     
    				materialParams.side = THREE.DoubleSide;
     
    			}
     
    			const alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;
    			if ( alphaMode === ALPHA_MODES.BLEND ) {
     
    				materialParams.transparent = true;
     
    				// See: https://github.com/mrdoob/three.js/issues/17706
    				materialParams.depthWrite = false;
     
    			} else {
     
    				materialParams.transparent = false;
    				if ( alphaMode === ALPHA_MODES.MASK ) {
     
    					materialParams.alphaTest = materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;
     
    				}
     
    			}
     
    			if ( materialDef.normalTexture !== undefined && materialType !== THREE.MeshBasicMaterial ) {
     
    				pending.push( parser.assignTexture( materialParams, 'normalMap', materialDef.normalTexture ) );
    				materialParams.normalScale = new THREE.Vector2( 1, 1 );
    				if ( materialDef.normalTexture.scale !== undefined ) {
     
    					const scale = materialDef.normalTexture.scale;
    					materialParams.normalScale.set( scale, scale );
     
    				}
     
    			}
     
    			if ( materialDef.occlusionTexture !== undefined && materialType !== THREE.MeshBasicMaterial ) {
     
    				pending.push( parser.assignTexture( materialParams, 'aoMap', materialDef.occlusionTexture ) );
    				if ( materialDef.occlusionTexture.strength !== undefined ) {
     
    					materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;
     
    				}
     
    			}
     
    			if ( materialDef.emissiveFactor !== undefined && materialType !== THREE.MeshBasicMaterial ) {
     
    				materialParams.emissive = new THREE.Color().fromArray( materialDef.emissiveFactor );
     
    			}
     
    			if ( materialDef.emissiveTexture !== undefined && materialType !== THREE.MeshBasicMaterial ) {
     
    				pending.push( parser.assignTexture( materialParams, 'emissiveMap', materialDef.emissiveTexture, THREE.sRGBEncoding ) );
     
    			}
     
    			return Promise.all( pending ).then( function () {
     
    				const material = new materialType( materialParams );
    				if ( materialDef.name ) material.name = materialDef.name;
    				assignExtrasToUserData( material, materialDef );
    				parser.associations.set( material, {
    					materials: materialIndex
    				} );
    				if ( materialDef.extensions ) addUnknownExtensionsToUserData( extensions, material, materialDef );
    				return material;
     
    			} );
     
    		}
     
    		/** When THREE.Object3D instances are targeted by animation, they need unique names. */
    		createUniqueName( originalName ) {
     
    			const sanitizedName = THREE.PropertyBinding.sanitizeNodeName( originalName || '' );
    			let name = sanitizedName;
    			for ( let i = 1; this.nodeNamesUsed[ name ]; ++ i ) {
     
    				name = sanitizedName + '_' + i;
     
    			}
     
    			this.nodeNamesUsed[ name ] = true;
    			return name;
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
       *
       * Creates BufferGeometries from primitives.
       *
       * @param {Array<GLTF.Primitive>} primitives
       * @return {Promise<Array<BufferGeometry>>}
       */
    		loadGeometries( primitives ) {
     
    			const parser = this;
    			const extensions = this.extensions;
    			const cache = this.primitiveCache;
    			function createDracoPrimitive( primitive ) {
     
    				return extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ].decodePrimitive( primitive, parser ).then( function ( geometry ) {
     
    					return addPrimitiveAttributes( geometry, primitive, parser );
     
    				} );
     
    			}
     
    			const pending = [];
    			for ( let i = 0, il = primitives.length; i < il; i ++ ) {
     
    				const primitive = primitives[ i ];
    				const cacheKey = createPrimitiveKey( primitive );
     
    				// See if we've already created this geometry
    				const cached = cache[ cacheKey ];
    				if ( cached ) {
     
    					// Use the cached geometry if it exists
    					pending.push( cached.promise );
     
    				} else {
     
    					let geometryPromise;
    					if ( primitive.extensions && primitive.extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ] ) {
     
    						// Use DRACO geometry if available
    						geometryPromise = createDracoPrimitive( primitive );
     
    					} else {
     
    						// Otherwise create a new geometry
    						geometryPromise = addPrimitiveAttributes( new THREE.BufferGeometry(), primitive, parser );
     
    					}
     
    					// Cache this geometry
    					cache[ cacheKey ] = {
    						primitive: primitive,
    						promise: geometryPromise
    					};
    					pending.push( geometryPromise );
     
    				}
     
    			}
     
    			return Promise.all( pending );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
       * @param {number} meshIndex
       * @return {Promise<Group|Mesh|SkinnedMesh>}
       */
    		loadMesh( meshIndex ) {
     
    			const parser = this;
    			const json = this.json;
    			const extensions = this.extensions;
    			const meshDef = json.meshes[ meshIndex ];
    			const primitives = meshDef.primitives;
    			const pending = [];
    			for ( let i = 0, il = primitives.length; i < il; i ++ ) {
     
    				const material = primitives[ i ].material === undefined ? createDefaultMaterial( this.cache ) : this.getDependency( 'material', primitives[ i ].material );
    				pending.push( material );
     
    			}
     
    			pending.push( parser.loadGeometries( primitives ) );
    			return Promise.all( pending ).then( function ( results ) {
     
    				const materials = results.slice( 0, results.length - 1 );
    				const geometries = results[ results.length - 1 ];
    				const meshes = [];
    				for ( let i = 0, il = geometries.length; i < il; i ++ ) {
     
    					const geometry = geometries[ i ];
    					const primitive = primitives[ i ];
     
    					// 1. create THREE.Mesh
     
    					let mesh;
    					const material = materials[ i ];
    					if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLES || primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP || primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN || primitive.mode === undefined ) {
     
    						// .isSkinnedMesh isn't in glTF spec. See ._markDefs()
    						mesh = meshDef.isSkinnedMesh === true ? new THREE.SkinnedMesh( geometry, material ) : new THREE.Mesh( geometry, material );
    						if ( mesh.isSkinnedMesh === true && ! mesh.geometry.attributes.skinWeight.normalized ) {
     
    							// we normalize floating point skin weight array to fix malformed assets (see #15319)
    							// it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
    							mesh.normalizeSkinWeights();
     
    						}
     
    						if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ) {
     
    							mesh.geometry = toTrianglesDrawMode( mesh.geometry, THREE.TriangleStripDrawMode );
     
    						} else if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ) {
     
    							mesh.geometry = toTrianglesDrawMode( mesh.geometry, THREE.TriangleFanDrawMode );
     
    						}
     
    					} else if ( primitive.mode === WEBGL_CONSTANTS.LINES ) {
     
    						mesh = new THREE.LineSegments( geometry, material );
     
    					} else if ( primitive.mode === WEBGL_CONSTANTS.LINE_STRIP ) {
     
    						mesh = new THREE.Line( geometry, material );
     
    					} else if ( primitive.mode === WEBGL_CONSTANTS.LINE_LOOP ) {
     
    						mesh = new THREE.LineLoop( geometry, material );
     
    					} else if ( primitive.mode === WEBGL_CONSTANTS.POINTS ) {
     
    						mesh = new THREE.Points( geometry, material );
     
    					} else {
     
    						throw new Error( 'THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode );
     
    					}
     
    					if ( Object.keys( mesh.geometry.morphAttributes ).length > 0 ) {
     
    						updateMorphTargets( mesh, meshDef );
     
    					}
     
    					mesh.name = parser.createUniqueName( meshDef.name || 'mesh_' + meshIndex );
    					assignExtrasToUserData( mesh, meshDef );
    					if ( primitive.extensions ) addUnknownExtensionsToUserData( extensions, mesh, primitive );
    					parser.assignFinalMaterial( mesh );
    					meshes.push( mesh );
     
    				}
     
    				for ( let i = 0, il = meshes.length; i < il; i ++ ) {
     
    					parser.associations.set( meshes[ i ], {
    						meshes: meshIndex,
    						primitives: i
    					} );
     
    				}
     
    				if ( meshes.length === 1 ) {
     
    					return meshes[ 0 ];
     
    				}
     
    				const group = new THREE.Group();
    				parser.associations.set( group, {
    					meshes: meshIndex
    				} );
    				for ( let i = 0, il = meshes.length; i < il; i ++ ) {
     
    					group.add( meshes[ i ] );
     
    				}
     
    				return group;
     
    			} );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
       * @param {number} cameraIndex
       * @return {Promise<THREE.Camera>}
       */
    		loadCamera( cameraIndex ) {
     
    			let camera;
    			const cameraDef = this.json.cameras[ cameraIndex ];
    			const params = cameraDef[ cameraDef.type ];
    			if ( ! params ) {
     
    				console.warn( 'THREE.GLTFLoader: Missing camera parameters.' );
    				return;
     
    			}
     
    			if ( cameraDef.type === 'perspective' ) {
     
    				camera = new THREE.PerspectiveCamera( THREE.MathUtils.radToDeg( params.yfov ), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6 );
     
    			} else if ( cameraDef.type === 'orthographic' ) {
     
    				camera = new THREE.OrthographicCamera( - params.xmag, params.xmag, params.ymag, - params.ymag, params.znear, params.zfar );
     
    			}
     
    			if ( cameraDef.name ) camera.name = this.createUniqueName( cameraDef.name );
    			assignExtrasToUserData( camera, cameraDef );
    			return Promise.resolve( camera );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
       * @param {number} skinIndex
       * @return {Promise<Skeleton>}
       */
    		loadSkin( skinIndex ) {
     
    			const skinDef = this.json.skins[ skinIndex ];
    			const pending = [];
    			for ( let i = 0, il = skinDef.joints.length; i < il; i ++ ) {
     
    				pending.push( this.getDependency( 'node', skinDef.joints[ i ] ) );
     
    			}
     
    			if ( skinDef.inverseBindMatrices !== undefined ) {
     
    				pending.push( this.getDependency( 'accessor', skinDef.inverseBindMatrices ) );
     
    			} else {
     
    				pending.push( null );
     
    			}
     
    			return Promise.all( pending ).then( function ( results ) {
     
    				const inverseBindMatrices = results.pop();
    				const jointNodes = results;
    				const bones = [];
    				const boneInverses = [];
    				for ( let i = 0, il = jointNodes.length; i < il; i ++ ) {
     
    					const jointNode = jointNodes[ i ];
    					if ( jointNode ) {
     
    						bones.push( jointNode );
    						const mat = new THREE.Matrix4();
    						if ( inverseBindMatrices !== null ) {
     
    							mat.fromArray( inverseBindMatrices.array, i * 16 );
     
    						}
     
    						boneInverses.push( mat );
     
    					} else {
     
    						console.warn( 'THREE.GLTFLoader: Joint "%s" could not be found.', skinDef.joints[ i ] );
     
    					}
     
    				}
     
    				return new THREE.Skeleton( bones, boneInverses );
     
    			} );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
       * @param {number} animationIndex
       * @return {Promise<AnimationClip>}
       */
    		loadAnimation( animationIndex ) {
     
    			const json = this.json;
    			const animationDef = json.animations[ animationIndex ];
    			const pendingNodes = [];
    			const pendingInputAccessors = [];
    			const pendingOutputAccessors = [];
    			const pendingSamplers = [];
    			const pendingTargets = [];
    			for ( let i = 0, il = animationDef.channels.length; i < il; i ++ ) {
     
    				const channel = animationDef.channels[ i ];
    				const sampler = animationDef.samplers[ channel.sampler ];
    				const target = channel.target;
    				const name = target.node;
    				const input = animationDef.parameters !== undefined ? animationDef.parameters[ sampler.input ] : sampler.input;
    				const output = animationDef.parameters !== undefined ? animationDef.parameters[ sampler.output ] : sampler.output;
    				pendingNodes.push( this.getDependency( 'node', name ) );
    				pendingInputAccessors.push( this.getDependency( 'accessor', input ) );
    				pendingOutputAccessors.push( this.getDependency( 'accessor', output ) );
    				pendingSamplers.push( sampler );
    				pendingTargets.push( target );
     
    			}
     
    			return Promise.all( [ Promise.all( pendingNodes ), Promise.all( pendingInputAccessors ), Promise.all( pendingOutputAccessors ), Promise.all( pendingSamplers ), Promise.all( pendingTargets ) ] ).then( function ( dependencies ) {
     
    				const nodes = dependencies[ 0 ];
    				const inputAccessors = dependencies[ 1 ];
    				const outputAccessors = dependencies[ 2 ];
    				const samplers = dependencies[ 3 ];
    				const targets = dependencies[ 4 ];
    				const tracks = [];
    				for ( let i = 0, il = nodes.length; i < il; i ++ ) {
     
    					const node = nodes[ i ];
    					const inputAccessor = inputAccessors[ i ];
    					const outputAccessor = outputAccessors[ i ];
    					const sampler = samplers[ i ];
    					const target = targets[ i ];
    					if ( node === undefined ) continue;
    					node.updateMatrix();
    					let TypedKeyframeTrack;
    					switch ( PATH_PROPERTIES[ target.path ] ) {
     
    						case PATH_PROPERTIES.weights:
    							TypedKeyframeTrack = THREE.NumberKeyframeTrack;
    							break;
    						case PATH_PROPERTIES.rotation:
    							TypedKeyframeTrack = THREE.QuaternionKeyframeTrack;
    							break;
    						case PATH_PROPERTIES.position:
    						case PATH_PROPERTIES.scale:
    						default:
    							TypedKeyframeTrack = THREE.VectorKeyframeTrack;
    							break;
     
    					}
     
    					const targetName = node.name ? node.name : node.uuid;
    					const interpolation = sampler.interpolation !== undefined ? INTERPOLATION[ sampler.interpolation ] : THREE.InterpolateLinear;
    					const targetNames = [];
    					if ( PATH_PROPERTIES[ target.path ] === PATH_PROPERTIES.weights ) {
     
    						node.traverse( function ( object ) {
     
    							if ( object.morphTargetInfluences ) {
     
    								targetNames.push( object.name ? object.name : object.uuid );
     
    							}
     
    						} );
     
    					} else {
     
    						targetNames.push( targetName );
     
    					}
     
    					let outputArray = outputAccessor.array;
    					if ( outputAccessor.normalized ) {
     
    						const scale = getNormalizedComponentScale( outputArray.constructor );
    						const scaled = new Float32Array( outputArray.length );
    						for ( let j = 0, jl = outputArray.length; j < jl; j ++ ) {
     
    							scaled[ j ] = outputArray[ j ] * scale;
     
    						}
     
    						outputArray = scaled;
     
    					}
     
    					for ( let j = 0, jl = targetNames.length; j < jl; j ++ ) {
     
    						const track = new TypedKeyframeTrack( targetNames[ j ] + '.' + PATH_PROPERTIES[ target.path ], inputAccessor.array, outputArray, interpolation );
     
    						// Override interpolation with custom factory method.
    						if ( sampler.interpolation === 'CUBICSPLINE' ) {
     
    							track.createInterpolant = function InterpolantFactoryMethodGLTFCubicSpline( result ) {
     
    								// A CUBICSPLINE keyframe in glTF has three output values for each input value,
    								// representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
    								// must be divided by three to get the interpolant's sampleSize argument.
     
    								const interpolantType = this instanceof THREE.QuaternionKeyframeTrack ? GLTFCubicSplineQuaternionInterpolant : GLTFCubicSplineInterpolant;
    								return new interpolantType( this.times, this.values, this.getValueSize() / 3, result );
     
    							};
     
    							// Mark as CUBICSPLINE. `track.getInterpolation()` doesn't support custom interpolants.
    							track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;
     
    						}
     
    						tracks.push( track );
     
    					}
     
    				}
     
    				const name = animationDef.name ? animationDef.name : 'animation_' + animationIndex;
    				return new THREE.AnimationClip( name, undefined, tracks );
     
    			} );
     
    		}
    		createNodeMesh( nodeIndex ) {
     
    			const json = this.json;
    			const parser = this;
    			const nodeDef = json.nodes[ nodeIndex ];
    			if ( nodeDef.mesh === undefined ) return null;
    			return parser.getDependency( 'mesh', nodeDef.mesh ).then( function ( mesh ) {
     
    				const node = parser._getNodeRef( parser.meshCache, nodeDef.mesh, mesh );
     
    				// if weights are provided on the node, override weights on the mesh.
    				if ( nodeDef.weights !== undefined ) {
     
    					node.traverse( function ( o ) {
     
    						if ( ! o.isMesh ) return;
    						for ( let i = 0, il = nodeDef.weights.length; i < il; i ++ ) {
     
    							o.morphTargetInfluences[ i ] = nodeDef.weights[ i ];
     
    						}
     
    					} );
     
    				}
     
    				return node;
     
    			} );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
       * @param {number} nodeIndex
       * @return {Promise<Object3D>}
       */
    		loadNode( nodeIndex ) {
     
    			const json = this.json;
    			const extensions = this.extensions;
    			const parser = this;
    			const nodeDef = json.nodes[ nodeIndex ];
     
    			// reserve node's name before its dependencies, so the root has the intended name.
    			const nodeName = nodeDef.name ? parser.createUniqueName( nodeDef.name ) : '';
    			return function () {
     
    				const pending = [];
    				const meshPromise = parser._invokeOne( function ( ext ) {
     
    					return ext.createNodeMesh && ext.createNodeMesh( nodeIndex );
     
    				} );
    				if ( meshPromise ) {
     
    					pending.push( meshPromise );
     
    				}
     
    				if ( nodeDef.camera !== undefined ) {
     
    					pending.push( parser.getDependency( 'camera', nodeDef.camera ).then( function ( camera ) {
     
    						return parser._getNodeRef( parser.cameraCache, nodeDef.camera, camera );
     
    					} ) );
     
    				}
     
    				parser._invokeAll( function ( ext ) {
     
    					return ext.createNodeAttachment && ext.createNodeAttachment( nodeIndex );
     
    				} ).forEach( function ( promise ) {
     
    					pending.push( promise );
     
    				} );
    				return Promise.all( pending );
     
    			}().then( function ( objects ) {
     
    				let node;
     
    				// .isBone isn't in glTF spec. See ._markDefs
    				if ( nodeDef.isBone === true ) {
     
    					node = new THREE.Bone();
     
    				} else if ( objects.length > 1 ) {
     
    					node = new THREE.Group();
     
    				} else if ( objects.length === 1 ) {
     
    					node = objects[ 0 ];
     
    				} else {
     
    					node = new THREE.Object3D();
     
    				}
     
    				if ( node !== objects[ 0 ] ) {
     
    					for ( let i = 0, il = objects.length; i < il; i ++ ) {
     
    						node.add( objects[ i ] );
     
    					}
     
    				}
     
    				if ( nodeDef.name ) {
     
    					node.userData.name = nodeDef.name;
    					node.name = nodeName;
     
    				}
     
    				assignExtrasToUserData( node, nodeDef );
    				if ( nodeDef.extensions ) addUnknownExtensionsToUserData( extensions, node, nodeDef );
    				if ( nodeDef.matrix !== undefined ) {
     
    					const matrix = new THREE.Matrix4();
    					matrix.fromArray( nodeDef.matrix );
    					node.applyMatrix4( matrix );
     
    				} else {
     
    					if ( nodeDef.translation !== undefined ) {
     
    						node.position.fromArray( nodeDef.translation );
     
    					}
     
    					if ( nodeDef.rotation !== undefined ) {
     
    						node.quaternion.fromArray( nodeDef.rotation );
     
    					}
     
    					if ( nodeDef.scale !== undefined ) {
     
    						node.scale.fromArray( nodeDef.scale );
     
    					}
     
    				}
     
    				if ( ! parser.associations.has( node ) ) {
     
    					parser.associations.set( node, {} );
     
    				}
     
    				parser.associations.get( node ).nodes = nodeIndex;
    				return node;
     
    			} );
     
    		}
     
    		/**
       * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
       * @param {number} sceneIndex
       * @return {Promise<Group>}
       */
    		loadScene( sceneIndex ) {
     
    			const json = this.json;
    			const extensions = this.extensions;
    			const sceneDef = this.json.scenes[ sceneIndex ];
    			const parser = this;
     
    			// THREE.Loader returns THREE.Group, not Scene.
    			// See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172
    			const scene = new THREE.Group();
    			if ( sceneDef.name ) scene.name = parser.createUniqueName( sceneDef.name );
    			assignExtrasToUserData( scene, sceneDef );
    			if ( sceneDef.extensions ) addUnknownExtensionsToUserData( extensions, scene, sceneDef );
    			const nodeIds = sceneDef.nodes || [];
    			const pending = [];
    			for ( let i = 0, il = nodeIds.length; i < il; i ++ ) {
     
    				pending.push( buildNodeHierarchy( nodeIds[ i ], scene, json, parser ) );
     
    			}
     
    			return Promise.all( pending ).then( function () {
     
    				// Removes dangling associations, associations that reference a node that
    				// didn't make it into the scene.
    				const reduceAssociations = node => {
     
    					const reducedAssociations = new Map();
    					for ( const [ key, value ] of parser.associations ) {
     
    						if ( key instanceof THREE.Material || key instanceof THREE.Texture ) {
     
    							reducedAssociations.set( key, value );
     
    						}
     
    					}
     
    					node.traverse( node => {
     
    						const mappings = parser.associations.get( node );
    						if ( mappings != null ) {
     
    							reducedAssociations.set( node, mappings );
     
    						}
     
    					} );
    					return reducedAssociations;
     
    				};
     
    				parser.associations = reduceAssociations( scene );
    				return scene;
     
    			} );
     
    		}
     
    	}
    	function buildNodeHierarchy( nodeId, parentObject, json, parser ) {
     
    		const nodeDef = json.nodes[ nodeId ];
    		return parser.getDependency( 'node', nodeId ).then( function ( node ) {
     
    			if ( nodeDef.skin === undefined ) return node;
     
    			// build skeleton here as well
     
    			return parser.getDependency( 'skin', nodeDef.skin ).then( function ( skeleton ) {
     
    				node.traverse( function ( mesh ) {
     
    					if ( ! mesh.isSkinnedMesh ) return;
    					mesh.bind( skeleton, mesh.matrixWorld );
     
    				} );
    				return node;
     
    			} );
     
    		} ).then( function ( node ) {
     
    			// build node hierachy
     
    			parentObject.add( node );
    			const pending = [];
    			if ( nodeDef.children ) {
     
    				const children = nodeDef.children;
    				for ( let i = 0, il = children.length; i < il; i ++ ) {
     
    					const child = children[ i ];
    					pending.push( buildNodeHierarchy( child, node, json, parser ) );
     
    				}
     
    			}
     
    			return Promise.all( pending );
     
    		} );
     
    	}
     
    	/**
     * @param {BufferGeometry} geometry
     * @param {GLTF.Primitive} primitiveDef
     * @param {GLTFParser} parser
     */
    	function computeBounds( geometry, primitiveDef, parser ) {
     
    		const attributes = primitiveDef.attributes;
    		const box = new THREE.Box3();
    		if ( attributes.POSITION !== undefined ) {
     
    			const accessor = parser.json.accessors[ attributes.POSITION ];
    			const min = accessor.min;
    			const max = accessor.max;
     
    			// glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.
     
    			if ( min !== undefined && max !== undefined ) {
     
    				box.set( new THREE.Vector3( min[ 0 ], min[ 1 ], min[ 2 ] ), new THREE.Vector3( max[ 0 ], max[ 1 ], max[ 2 ] ) );
    				if ( accessor.normalized ) {
     
    					const boxScale = getNormalizedComponentScale( WEBGL_COMPONENT_TYPES[ accessor.componentType ] );
    					box.min.multiplyScalar( boxScale );
    					box.max.multiplyScalar( boxScale );
     
    				}
     
    			} else {
     
    				console.warn( 'THREE.GLTFLoader: Missing min/max properties for accessor POSITION.' );
    				return;
     
    			}
     
    		} else {
     
    			return;
     
    		}
     
    		const targets = primitiveDef.targets;
    		if ( targets !== undefined ) {
     
    			const maxDisplacement = new THREE.Vector3();
    			const vector = new THREE.Vector3();
    			for ( let i = 0, il = targets.length; i < il; i ++ ) {
     
    				const target = targets[ i ];
    				if ( target.POSITION !== undefined ) {
     
    					const accessor = parser.json.accessors[ target.POSITION ];
    					const min = accessor.min;
    					const max = accessor.max;
     
    					// glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.
     
    					if ( min !== undefined && max !== undefined ) {
     
    						// we need to get max of absolute components because target weight is [-1,1]
    						vector.setX( Math.max( Math.abs( min[ 0 ] ), Math.abs( max[ 0 ] ) ) );
    						vector.setY( Math.max( Math.abs( min[ 1 ] ), Math.abs( max[ 1 ] ) ) );
    						vector.setZ( Math.max( Math.abs( min[ 2 ] ), Math.abs( max[ 2 ] ) ) );
    						if ( accessor.normalized ) {
     
    							const boxScale = getNormalizedComponentScale( WEBGL_COMPONENT_TYPES[ accessor.componentType ] );
    							vector.multiplyScalar( boxScale );
     
    						}
     
    						// Note: this assumes that the sum of all weights is at most 1. This isn't quite correct - it's more conservative
    						// to assume that each target can have a max weight of 1. However, for some use cases - notably, when morph targets
    						// are used to implement key-frame animations and as such only two are active at a time - this results in very large
    						// boxes. So for now we make a box that's sometimes a touch too small but is hopefully mostly of reasonable size.
    						maxDisplacement.max( vector );
     
    					} else {
     
    						console.warn( 'THREE.GLTFLoader: Missing min/max properties for accessor POSITION.' );
     
    					}
     
    				}
     
    			}
     
    			// As per comment above this box isn't conservative, but has a reasonable size for a very large number of morph targets.
    			box.expandByVector( maxDisplacement );
     
    		}
     
    		geometry.boundingBox = box;
    		const sphere = new THREE.Sphere();
    		box.getCenter( sphere.center );
    		sphere.radius = box.min.distanceTo( box.max ) / 2;
    		geometry.boundingSphere = sphere;
     
    	}
     
    	/**
     * @param {BufferGeometry} geometry
     * @param {GLTF.Primitive} primitiveDef
     * @param {GLTFParser} parser
     * @return {Promise<BufferGeometry>}
     */
    	function addPrimitiveAttributes( geometry, primitiveDef, parser ) {
     
    		const attributes = primitiveDef.attributes;
    		const pending = [];
    		function assignAttributeAccessor( accessorIndex, attributeName ) {
     
    			return parser.getDependency( 'accessor', accessorIndex ).then( function ( accessor ) {
     
    				geometry.setAttribute( attributeName, accessor );
     
    			} );
     
    		}
     
    		for ( const gltfAttributeName in attributes ) {
     
    			const threeAttributeName = ATTRIBUTES[ gltfAttributeName ] || gltfAttributeName.toLowerCase();
     
    			// Skip attributes already provided by e.g. Draco extension.
    			if ( threeAttributeName in geometry.attributes ) continue;
    			pending.push( assignAttributeAccessor( attributes[ gltfAttributeName ], threeAttributeName ) );
     
    		}
     
    		if ( primitiveDef.indices !== undefined && ! geometry.index ) {
     
    			const accessor = parser.getDependency( 'accessor', primitiveDef.indices ).then( function ( accessor ) {
     
    				geometry.setIndex( accessor );
     
    			} );
    			pending.push( accessor );
     
    		}
     
    		assignExtrasToUserData( geometry, primitiveDef );
    		computeBounds( geometry, primitiveDef, parser );
    		return Promise.all( pending ).then( function () {
     
    			return primitiveDef.targets !== undefined ? addMorphTargets( geometry, primitiveDef.targets, parser ) : geometry;
     
    		} );
     
    	}
     
    	/**
     * @param {BufferGeometry} geometry
     * @param {Number} drawMode
     * @return {BufferGeometry}
     */
    	function toTrianglesDrawMode( geometry, drawMode ) {
     
    		let index = geometry.getIndex();
     
    		// generate index if not present
     
    		if ( index === null ) {
     
    			const indices = [];
    			const position = geometry.getAttribute( 'position' );
    			if ( position !== undefined ) {
     
    				for ( let i = 0; i < position.count; i ++ ) {
     
    					indices.push( i );
     
    				}
     
    				geometry.setIndex( indices );
    				index = geometry.getIndex();
     
    			} else {
     
    				console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.' );
    				return geometry;
     
    			}
     
    		}
     
    		//
     
    		const numberOfTriangles = index.count - 2;
    		const newIndices = [];
    		if ( drawMode === THREE.TriangleFanDrawMode ) {
     
    			// gl.TRIANGLE_FAN
     
    			for ( let i = 1; i <= numberOfTriangles; i ++ ) {
     
    				newIndices.push( index.getX( 0 ) );
    				newIndices.push( index.getX( i ) );
    				newIndices.push( index.getX( i + 1 ) );
     
    			}
     
    		} else {
     
    			// gl.TRIANGLE_STRIP
     
    			for ( let i = 0; i < numberOfTriangles; i ++ ) {
     
    				if ( i % 2 === 0 ) {
     
    					newIndices.push( index.getX( i ) );
    					newIndices.push( index.getX( i + 1 ) );
    					newIndices.push( index.getX( i + 2 ) );
     
    				} else {
     
    					newIndices.push( index.getX( i + 2 ) );
    					newIndices.push( index.getX( i + 1 ) );
    					newIndices.push( index.getX( i ) );
     
    				}
     
    			}
     
    		}
     
    		if ( newIndices.length / 3 !== numberOfTriangles ) {
     
    			console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles.' );
     
    		}
     
    		// build final geometry
     
    		const newGeometry = geometry.clone();
    		newGeometry.setIndex( newIndices );
    		return newGeometry;
     
    	}
     
    	THREE.GLTFLoader = GLTFLoader;
     
    } )();