three.js/examples/js/loaders/GLTFLoader.js

( function () {

	var GLTFLoader = function () {

		function GLTFLoader( manager ) {

			THREE.Loader.call( this, 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 GLTFMaterialsTransmissionExtension( parser );

			} );
			this.register( function ( parser ) {

				return new GLTFLightsExtension( parser );

			} );
			this.register( function ( parser ) {

				return new GLTFMeshoptCompression( parser );

			} );

		}

		GLTFLoader.prototype = Object.assign( Object.create( THREE.Loader.prototype ), {
			constructor: GLTFLoader,
			load: function ( url, onLoad, onProgress, onError ) {

				var scope = this;
				var resourcePath;

				if ( this.resourcePath !== '' ) {

					resourcePath = this.resourcePath;

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

					resourcePath = this.path;

				} else {

					resourcePath = 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 );

				var _onError = function ( e ) {

					if ( onError ) {

						onError( e );

					} else {

						console.error( e );

					}

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

				};

				var 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: function ( dracoLoader ) {

				this.dracoLoader = dracoLoader;
				return this;

			},
			setDDSLoader: function () {

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

			},
			setKTX2Loader: function ( ktx2Loader ) {

				this.ktx2Loader = ktx2Loader;
				return this;

			},
			setMeshoptDecoder: function ( meshoptDecoder ) {

				this.meshoptDecoder = meshoptDecoder;
				return this;

			},
			register: function ( callback ) {

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

					this.pluginCallbacks.push( callback );

				}

				return this;

			},
			unregister: function ( callback ) {

				if ( this.pluginCallbacks.indexOf( callback ) !== - 1 ) {

					this.pluginCallbacks.splice( this.pluginCallbacks.indexOf( callback ), 1 );

				}

				return this;

			},
			parse: function ( data, path, onLoad, onError ) {

				var content;
				var extensions = {};
				var plugins = {};

				if ( typeof data === 'string' ) {

					content = data;

				} else {

					var magic = THREE.LoaderUtils.decodeText( new Uint8Array( data, 0, 4 ) );

					if ( magic === BINARY_EXTENSION_HEADER_MAGIC ) {

						try {

							extensions[ EXTENSIONS.KHR_BINARY_GLTF ] = new GLTFBinaryExtension( data );

						} catch ( error ) {

							if ( onError ) onError( error );
							return;

						}

						content = extensions[ EXTENSIONS.KHR_BINARY_GLTF ].content;

					} else {

						content = THREE.LoaderUtils.decodeText( new Uint8Array( data ) );

					}

				}

				var json = JSON.parse( content );

				if ( json.asset === undefined || json.asset.version[ 0 ] < 2 ) {

					if ( onError ) onError( new Error( 'THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported.' ) );
					return;

				}

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

				for ( var i = 0; i < this.pluginCallbacks.length; i ++ ) {

					var plugin = this.pluginCallbacks[ i ]( parser );
					plugins[ plugin.name ] = plugin; // Workaround to avoid determining as unknown extension
					// in addUnknownExtensionsToUserData().
					// Remove this workaround if we move all the existing
					// extension handlers to plugin system

					extensions[ plugin.name ] = true;

				}

				if ( json.extensionsUsed ) {

					for ( var i = 0; i < json.extensionsUsed.length; ++ i ) {

						var extensionName = json.extensionsUsed[ i ];
						var extensionsRequired = json.extensionsRequired || [];

						switch ( extensionName ) {

							case EXTENSIONS.KHR_MATERIALS_UNLIT:
								extensions[ extensionName ] = new GLTFMaterialsUnlitExtension();
								break;

							case EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
								extensions[ extensionName ] = new GLTFMaterialsPbrSpecularGlossinessExtension();
								break;

							case EXTENSIONS.KHR_DRACO_MESH_COMPRESSION:
								extensions[ extensionName ] = new GLTFDracoMeshCompressionExtension( json, this.dracoLoader );
								break;

							case EXTENSIONS.KHR_TEXTURE_TRANSFORM:
								extensions[ extensionName ] = new GLTFTextureTransformExtension();
								break;

							case EXTENSIONS.KHR_MESH_QUANTIZATION:
								extensions[ extensionName ] = new GLTFMeshQuantizationExtension();
								break;

							default:
								if ( extensionsRequired.indexOf( extensionName ) >= 0 && plugins[ extensionName ] === undefined ) {

									console.warn( 'THREE.GLTFLoader: Unknown extension "' + extensionName + '".' );

								}

						}

					}

				}

				parser.setExtensions( extensions );
				parser.setPlugins( plugins );
				parser.parse( onLoad, onError );

			}
		} );
		/* GLTFREGISTRY */

		function GLTFRegistry() {

			var objects = {};
			return {
				get: function ( key ) {

					return objects[ key ];

				},
				add: function ( key, object ) {

					objects[ key ] = object;

				},
				remove: function ( key ) {

					delete objects[ key ];

				},
				removeAll: function () {

					objects = {};

				}
			};

		}
		/*********************************/

		/********** EXTENSIONS ***********/

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


		var EXTENSIONS = {
			KHR_BINARY_GLTF: 'KHR_binary_glTF',
			KHR_DRACO_MESH_COMPRESSION: 'KHR_draco_mesh_compression',
			KHR_LIGHTS_PUNCTUAL: 'KHR_lights_punctual',
			KHR_MATERIALS_CLEARCOAT: 'KHR_materials_clearcoat',
			KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
			KHR_MATERIALS_TRANSMISSION: 'KHR_materials_transmission',
			KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
			KHR_TEXTURE_BASISU: 'KHR_texture_basisu',
			KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
			KHR_MESH_QUANTIZATION: 'KHR_mesh_quantization',
			EXT_TEXTURE_WEBP: 'EXT_texture_webp',
			EXT_MESHOPT_COMPRESSION: 'EXT_meshopt_compression'
		};
		/**
	 * Punctual Lights Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
	 */

		function GLTFLightsExtension( parser ) {

			this.parser = parser;
			this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL; // THREE.Object3D instance caches

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

		}

		GLTFLightsExtension.prototype._markDefs = function () {

			var parser = this.parser;
			var nodeDefs = this.parser.json.nodes || [];

			for ( var nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex ++ ) {

				var nodeDef = nodeDefs[ nodeIndex ];

				if ( nodeDef.extensions && nodeDef.extensions[ this.name ] && nodeDef.extensions[ this.name ].light !== undefined ) {

					parser._addNodeRef( this.cache, nodeDef.extensions[ this.name ].light );

				}

			}

		};

		GLTFLightsExtension.prototype._loadLight = function ( lightIndex ) {

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

			switch ( lightDef.type ) {

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

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

				case 'spot':
					lightNode = new THREE.SpotLight( color );
					lightNode.distance = range; // Handle spotlight properties.

					lightDef.spot = lightDef.spot || {};
					lightDef.spot.innerConeAngle = lightDef.spot.innerConeAngle !== undefined ? lightDef.spot.innerConeAngle : 0;
					lightDef.spot.outerConeAngle = lightDef.spot.outerConeAngle !== undefined ? lightDef.spot.outerConeAngle : Math.PI / 4.0;
					lightNode.angle = lightDef.spot.outerConeAngle;
					lightNode.penumbra = 1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
					lightNode.target.position.set( 0, 0, - 1 );
					lightNode.add( lightNode.target );
					break;

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

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


			lightNode.position.set( 0, 0, 0 );
			lightNode.decay = 2;
			if ( lightDef.intensity !== undefined ) lightNode.intensity = lightDef.intensity;
			lightNode.name = parser.createUniqueName( lightDef.name || 'light_' + lightIndex );
			dependency = Promise.resolve( lightNode );
			parser.cache.add( cacheKey, dependency );
			return dependency;

		};

		GLTFLightsExtension.prototype.createNodeAttachment = function ( nodeIndex ) {

			var self = this;
			var parser = this.parser;
			var json = parser.json;
			var nodeDef = json.nodes[ nodeIndex ];
			var lightDef = nodeDef.extensions && nodeDef.extensions[ this.name ] || {};
			var lightIndex = lightDef.light;
			if ( lightIndex === undefined ) return null;
			return this._loadLight( lightIndex ).then( function ( light ) {

				return parser._getNodeRef( self.cache, lightIndex, light );

			} );

		};
		/**
	 * Unlit Materials Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
	 */


		function GLTFMaterialsUnlitExtension() {

			this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;

		}

		GLTFMaterialsUnlitExtension.prototype.getMaterialType = function () {

			return THREE.MeshBasicMaterial;

		};

		GLTFMaterialsUnlitExtension.prototype.extendParams = function ( materialParams, materialDef, parser ) {

			var pending = [];
			materialParams.color = new THREE.Color( 1.0, 1.0, 1.0 );
			materialParams.opacity = 1.0;
			var metallicRoughness = materialDef.pbrMetallicRoughness;

			if ( metallicRoughness ) {

				if ( Array.isArray( metallicRoughness.baseColorFactor ) ) {

					var array = metallicRoughness.baseColorFactor;
					materialParams.color.fromArray( array );
					materialParams.opacity = array[ 3 ];

				}

				if ( metallicRoughness.baseColorTexture !== undefined ) {

					pending.push( parser.assignTexture( materialParams, 'map', metallicRoughness.baseColorTexture ) );

				}

			}

			return Promise.all( pending );

		};
		/**
	 * Clearcoat Materials Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
	 */


		function GLTFMaterialsClearcoatExtension( parser ) {

			this.parser = parser;
			this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;

		}

		GLTFMaterialsClearcoatExtension.prototype.getMaterialType = function ( materialIndex ) {

			var parser = this.parser;
			var materialDef = parser.json.materials[ materialIndex ];
			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
			return THREE.MeshPhysicalMaterial;

		};

		GLTFMaterialsClearcoatExtension.prototype.extendMaterialParams = function ( materialIndex, materialParams ) {

			var parser = this.parser;
			var materialDef = parser.json.materials[ materialIndex ];

			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

				return Promise.resolve();

			}

			var pending = [];
			var extension = materialDef.extensions[ this.name ];

			if ( extension.clearcoatFactor !== undefined ) {

				materialParams.clearcoat = extension.clearcoatFactor;

			}

			if ( extension.clearcoatTexture !== undefined ) {

				pending.push( parser.assignTexture( materialParams, 'clearcoatMap', extension.clearcoatTexture ) );

			}

			if ( extension.clearcoatRoughnessFactor !== undefined ) {

				materialParams.clearcoatRoughness = extension.clearcoatRoughnessFactor;

			}

			if ( extension.clearcoatRoughnessTexture !== undefined ) {

				pending.push( parser.assignTexture( materialParams, 'clearcoatRoughnessMap', extension.clearcoatRoughnessTexture ) );

			}

			if ( extension.clearcoatNormalTexture !== undefined ) {

				pending.push( parser.assignTexture( materialParams, 'clearcoatNormalMap', extension.clearcoatNormalTexture ) );

				if ( extension.clearcoatNormalTexture.scale !== undefined ) {

					var scale = extension.clearcoatNormalTexture.scale; // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995

					materialParams.clearcoatNormalScale = new THREE.Vector2( scale, - scale );

				}

			}

			return Promise.all( pending );

		};
		/**
	 * Transmission Materials Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_transmission
	 * Draft: https://github.com/KhronosGroup/glTF/pull/1698
	 */


		function GLTFMaterialsTransmissionExtension( parser ) {

			this.parser = parser;
			this.name = EXTENSIONS.KHR_MATERIALS_TRANSMISSION;

		}

		GLTFMaterialsTransmissionExtension.prototype.getMaterialType = function ( materialIndex ) {

			var parser = this.parser;
			var materialDef = parser.json.materials[ materialIndex ];
			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;
			return THREE.MeshPhysicalMaterial;

		};

		GLTFMaterialsTransmissionExtension.prototype.extendMaterialParams = function ( materialIndex, materialParams ) {

			var parser = this.parser;
			var materialDef = parser.json.materials[ materialIndex ];

			if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

				return Promise.resolve();

			}

			var pending = [];
			var extension = materialDef.extensions[ this.name ];

			if ( extension.transmissionFactor !== undefined ) {

				materialParams.transmission = extension.transmissionFactor;

			}

			if ( extension.transmissionTexture !== undefined ) {

				pending.push( parser.assignTexture( materialParams, 'transmissionMap', extension.transmissionTexture ) );

			}

			return Promise.all( pending );

		};
		/**
	 * BasisU Texture Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu
	 */


		function GLTFTextureBasisUExtension( parser ) {

			this.parser = parser;
			this.name = EXTENSIONS.KHR_TEXTURE_BASISU;

		}

		GLTFTextureBasisUExtension.prototype.loadTexture = function ( textureIndex ) {

			var parser = this.parser;
			var json = parser.json;
			var textureDef = json.textures[ textureIndex ];

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

				return null;

			}

			var extension = textureDef.extensions[ this.name ];
			var source = json.images[ extension.source ];
			var loader = parser.options.ktx2Loader;

			if ( ! loader ) {

				if ( json.extensionsRequired && json.extensionsRequired.indexOf( this.name ) >= 0 ) {

					throw new Error( 'THREE.GLTFLoader: setKTX2Loader must be called before loading KTX2 textures' );

				} else {

					// Assumes that the extension is optional and that a fallback texture is present
					return null;

				}

			}

			return parser.loadTextureImage( textureIndex, source, loader );

		};
		/**
	 * WebP Texture Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_texture_webp
	 */


		function GLTFTextureWebPExtension( parser ) {

			this.parser = parser;
			this.name = EXTENSIONS.EXT_TEXTURE_WEBP;
			this.isSupported = null;

		}

		GLTFTextureWebPExtension.prototype.loadTexture = function ( textureIndex ) {

			var name = this.name;
			var parser = this.parser;
			var json = parser.json;
			var textureDef = json.textures[ textureIndex ];

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

				return null;

			}

			var extension = textureDef.extensions[ name ];
			var source = json.images[ extension.source ];
			var loader = parser.textureLoader;

			if ( source.uri ) {

				var handler = parser.options.manager.getHandler( source.uri );
				if ( handler !== null ) loader = handler;

			}

			return this.detectSupport().then( function ( isSupported ) {

				if ( isSupported ) return parser.loadTextureImage( textureIndex, source, loader );

				if ( json.extensionsRequired && json.extensionsRequired.indexOf( name ) >= 0 ) {

					throw new Error( 'THREE.GLTFLoader: WebP required by asset but unsupported.' );

				} // Fall back to PNG or JPEG.


				return parser.loadTexture( textureIndex );

			} );

		};

		GLTFTextureWebPExtension.prototype.detectSupport = function () {

			if ( ! this.isSupported ) {

				this.isSupported = new Promise( function ( resolve ) {

					var image = new Image(); // Lossy test image. Support for lossy images doesn't guarantee support for all
					// WebP images, unfortunately.

					image.src = 'data:image/webp;base64,UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA';

					image.onload = image.onerror = function () {

						resolve( image.height === 1 );

					};

				} );

			}

			return this.isSupported;

		};
		/**
	* meshopt BufferView Compression Extension
	*
	* Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_meshopt_compression
	*/


		function GLTFMeshoptCompression( parser ) {

			this.name = EXTENSIONS.EXT_MESHOPT_COMPRESSION;
			this.parser = parser;

		}

		GLTFMeshoptCompression.prototype.loadBufferView = function ( index ) {

			var json = this.parser.json;
			var bufferView = json.bufferViews[ index ];

			if ( bufferView.extensions && bufferView.extensions[ this.name ] ) {

				var extensionDef = bufferView.extensions[ this.name ];
				var buffer = this.parser.getDependency( 'buffer', extensionDef.buffer );
				var decoder = this.parser.options.meshoptDecoder;

				if ( ! decoder || ! decoder.supported ) {

					if ( json.extensionsRequired && json.extensionsRequired.indexOf( this.name ) >= 0 ) {

						throw new Error( 'THREE.GLTFLoader: setMeshoptDecoder must be called before loading compressed files' );

					} else {

						// Assumes that the extension is optional and that fallback buffer data is present
						return null;

					}

				}

				return Promise.all( [ buffer, decoder.ready ] ).then( function ( res ) {

					var byteOffset = extensionDef.byteOffset || 0;
					var byteLength = extensionDef.byteLength || 0;
					var count = extensionDef.count;
					var stride = extensionDef.byteStride;
					var result = new ArrayBuffer( count * stride );
					var source = new Uint8Array( res[ 0 ], byteOffset, byteLength );
					decoder.decodeGltfBuffer( new Uint8Array( result ), count, stride, source, extensionDef.mode, extensionDef.filter );
					return result;

				} );

			} else {

				return null;

			}

		};
		/* BINARY EXTENSION */


		var BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
		var BINARY_EXTENSION_HEADER_LENGTH = 12;
		var BINARY_EXTENSION_CHUNK_TYPES = {
			JSON: 0x4E4F534A,
			BIN: 0x004E4942
		};

		function GLTFBinaryExtension( data ) {

			this.name = EXTENSIONS.KHR_BINARY_GLTF;
			this.content = null;
			this.body = null;
			var headerView = new DataView( data, 0, BINARY_EXTENSION_HEADER_LENGTH );
			this.header = {
				magic: 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.' );

			}

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

			while ( chunkIndex < chunkContentsLength ) {

				var chunkLength = chunkView.getUint32( chunkIndex, true );
				chunkIndex += 4;
				var chunkType = chunkView.getUint32( chunkIndex, true );
				chunkIndex += 4;

				if ( chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON ) {

					var contentArray = new Uint8Array( data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength );
					this.content = THREE.LoaderUtils.decodeText( contentArray );

				} else if ( chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN ) {

					var byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
					this.body = data.slice( byteOffset, byteOffset + chunkLength );

				} // Clients must ignore chunks with unknown types.


				chunkIndex += chunkLength;

			}

			if ( this.content === null ) {

				throw new Error( 'THREE.GLTFLoader: JSON content not found.' );

			}

		}
		/**
	 * DRACO THREE.Mesh Compression Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
	 */


		function GLTFDracoMeshCompressionExtension( json, dracoLoader ) {

			if ( ! dracoLoader ) {

				throw new Error( 'THREE.GLTFLoader: No DRACOLoader instance provided.' );

			}

			this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
			this.json = json;
			this.dracoLoader = dracoLoader;
			this.dracoLoader.preload();

		}

		GLTFDracoMeshCompressionExtension.prototype.decodePrimitive = function ( primitive, parser ) {

			var json = this.json;
			var dracoLoader = this.dracoLoader;
			var bufferViewIndex = primitive.extensions[ this.name ].bufferView;
			var gltfAttributeMap = primitive.extensions[ this.name ].attributes;
			var threeAttributeMap = {};
			var attributeNormalizedMap = {};
			var attributeTypeMap = {};

			for ( var attributeName in gltfAttributeMap ) {

				var threeAttributeName = ATTRIBUTES[ attributeName ] || attributeName.toLowerCase();
				threeAttributeMap[ threeAttributeName ] = gltfAttributeMap[ attributeName ];

			}

			for ( attributeName in primitive.attributes ) {

				var threeAttributeName = ATTRIBUTES[ attributeName ] || attributeName.toLowerCase();

				if ( gltfAttributeMap[ attributeName ] !== undefined ) {

					var accessorDef = json.accessors[ primitive.attributes[ attributeName ] ];
					var componentType = WEBGL_COMPONENT_TYPES[ accessorDef.componentType ];
					attributeTypeMap[ threeAttributeName ] = componentType;
					attributeNormalizedMap[ threeAttributeName ] = accessorDef.normalized === true;

				}

			}

			return parser.getDependency( 'bufferView', bufferViewIndex ).then( function ( bufferView ) {

				return new Promise( function ( resolve ) {

					dracoLoader.decodeDracoFile( bufferView, function ( geometry ) {

						for ( var attributeName in geometry.attributes ) {

							var attribute = geometry.attributes[ attributeName ];
							var normalized = attributeNormalizedMap[ attributeName ];
							if ( normalized !== undefined ) attribute.normalized = normalized;

						}

						resolve( geometry );

					}, threeAttributeMap, attributeTypeMap );

				} );

			} );

		};
		/**
	 * Texture Transform Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
	 */


		function GLTFTextureTransformExtension() {

			this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;

		}

		GLTFTextureTransformExtension.prototype.extendTexture = function ( texture, transform ) {

			texture = texture.clone();

			if ( transform.offset !== undefined ) {

				texture.offset.fromArray( transform.offset );

			}

			if ( transform.rotation !== undefined ) {

				texture.rotation = transform.rotation;

			}

			if ( transform.scale !== undefined ) {

				texture.repeat.fromArray( transform.scale );

			}

			if ( transform.texCoord !== undefined ) {

				console.warn( 'THREE.GLTFLoader: Custom UV sets in "' + this.name + '" extension not yet supported.' );

			}

			texture.needsUpdate = true;
			return texture;

		};
		/**
	 * Specular-Glossiness Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness
	 */

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


		function GLTFMeshStandardSGMaterial( params ) {

			THREE.MeshStandardMaterial.call( this );
			this.isGLTFSpecularGlossinessMaterial = true; //various chunks that need replacing

			var specularMapParsFragmentChunk = [ '#ifdef USE_SPECULARMAP', '	uniform sampler2D specularMap;', '#endif' ].join( '\n' );
			var glossinessMapParsFragmentChunk = [ '#ifdef USE_GLOSSINESSMAP', '	uniform sampler2D glossinessMap;', '#endif' ].join( '\n' );
			var specularMapFragmentChunk = [ 'vec3 specularFactor = specular;', '#ifdef USE_SPECULARMAP', '	vec4 texelSpecular = texture2D( specularMap, vUv );', '	texelSpecular = sRGBToLinear( texelSpecular );', '	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture', '	specularFactor *= texelSpecular.rgb;', '#endif' ].join( '\n' );
			var glossinessMapFragmentChunk = [ 'float glossinessFactor = glossiness;', '#ifdef USE_GLOSSINESSMAP', '	vec4 texelGlossiness = texture2D( glossinessMap, vUv );', '	// reads channel A, compatible with a glTF Specular-Glossiness (RGBA) texture', '	glossinessFactor *= texelGlossiness.a;', '#endif' ].join( '\n' );
			var lightPhysicalFragmentChunk = [ 'PhysicalMaterial material;', 'material.diffuseColor = diffuseColor.rgb * ( 1. - max( specularFactor.r, max( specularFactor.g, specularFactor.b ) ) );', 'vec3 dxy = max( abs( dFdx( geometryNormal ) ), abs( dFdy( geometryNormal ) ) );', 'float geometryRoughness = max( max( dxy.x, dxy.y ), dxy.z );', 'material.specularRoughness = max( 1.0 - glossinessFactor, 0.0525 ); // 0.0525 corresponds to the base mip of a 256 cubemap.', 'material.specularRoughness += geometryRoughness;', 'material.specularRoughness = min( material.specularRoughness, 1.0 );', 'material.specularColor = specularFactor;' ].join( '\n' );
			var uniforms = {
				specular: {
					value: new THREE.Color().setHex( 0xffffff )
				},
				glossiness: {
					value: 1
				},
				specularMap: {
					value: null
				},
				glossinessMap: {
					value: null
				}
			};
			this._extraUniforms = uniforms;

			this.onBeforeCompile = function ( shader ) {

				for ( var uniformName in uniforms ) {

					shader.uniforms[ uniformName ] = uniforms[ uniformName ];

				}

				shader.fragmentShader = shader.fragmentShader.replace( 'uniform float roughness;', 'uniform vec3 specular;' ).replace( 'uniform float metalness;', 'uniform float glossiness;' ).replace( '#include <roughnessmap_pars_fragment>', specularMapParsFragmentChunk ).replace( '#include <metalnessmap_pars_fragment>', glossinessMapParsFragmentChunk ).replace( '#include <roughnessmap_fragment>', specularMapFragmentChunk ).replace( '#include <metalnessmap_fragment>', glossinessMapFragmentChunk ).replace( '#include <lights_physical_fragment>', lightPhysicalFragmentChunk );

			};

			Object.defineProperties( this, {
				specular: {
					get: function () {

						return uniforms.specular.value;

					},
					set: function ( v ) {

						uniforms.specular.value = v;

					}
				},
				specularMap: {
					get: function () {

						return uniforms.specularMap.value;

					},
					set: function ( v ) {

						uniforms.specularMap.value = v;

						if ( v ) {

							this.defines.USE_SPECULARMAP = ''; // USE_UV is set by the renderer for specular maps

						} else {

							delete this.defines.USE_SPECULARMAP;

						}

					}
				},
				glossiness: {
					get: function () {

						return uniforms.glossiness.value;

					},
					set: function ( v ) {

						uniforms.glossiness.value = v;

					}
				},
				glossinessMap: {
					get: function () {

						return uniforms.glossinessMap.value;

					},
					set: function ( v ) {

						uniforms.glossinessMap.value = v;

						if ( v ) {

							this.defines.USE_GLOSSINESSMAP = '';
							this.defines.USE_UV = '';

						} else {

							delete this.defines.USE_GLOSSINESSMAP;
							delete this.defines.USE_UV;

						}

					}
				}
			} );
			delete this.metalness;
			delete this.roughness;
			delete this.metalnessMap;
			delete this.roughnessMap;
			this.setValues( params );

		}

		GLTFMeshStandardSGMaterial.prototype = Object.create( THREE.MeshStandardMaterial.prototype );
		GLTFMeshStandardSGMaterial.prototype.constructor = GLTFMeshStandardSGMaterial;

		GLTFMeshStandardSGMaterial.prototype.copy = function ( source ) {

			THREE.MeshStandardMaterial.prototype.copy.call( this, source );
			this.specularMap = source.specularMap;
			this.specular.copy( source.specular );
			this.glossinessMap = source.glossinessMap;
			this.glossiness = source.glossiness;
			delete this.metalness;
			delete this.roughness;
			delete this.metalnessMap;
			delete this.roughnessMap;
			return this;

		};

		function GLTFMaterialsPbrSpecularGlossinessExtension() {

			return {
				name: EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS,
				specularGlossinessParams: [ 'color', 'map', 'lightMap', 'lightMapIntensity', 'aoMap', 'aoMapIntensity', 'emissive', 'emissiveIntensity', 'emissiveMap', 'bumpMap', 'bumpScale', 'normalMap', 'normalMapType', 'displacementMap', 'displacementScale', 'displacementBias', 'specularMap', 'specular', 'glossinessMap', 'glossiness', 'alphaMap', 'envMap', 'envMapIntensity', 'refractionRatio' ],
				getMaterialType: function () {

					return GLTFMeshStandardSGMaterial;

				},
				extendParams: function ( materialParams, materialDef, parser ) {

					var pbrSpecularGlossiness = materialDef.extensions[ this.name ];
					materialParams.color = new THREE.Color( 1.0, 1.0, 1.0 );
					materialParams.opacity = 1.0;
					var pending = [];

					if ( Array.isArray( pbrSpecularGlossiness.diffuseFactor ) ) {

						var array = pbrSpecularGlossiness.diffuseFactor;
						materialParams.color.fromArray( array );
						materialParams.opacity = array[ 3 ];

					}

					if ( pbrSpecularGlossiness.diffuseTexture !== undefined ) {

						pending.push( parser.assignTexture( materialParams, 'map', pbrSpecularGlossiness.diffuseTexture ) );

					}

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

					if ( Array.isArray( pbrSpecularGlossiness.specularFactor ) ) {

						materialParams.specular.fromArray( pbrSpecularGlossiness.specularFactor );

					}

					if ( pbrSpecularGlossiness.specularGlossinessTexture !== undefined ) {

						var specGlossMapDef = pbrSpecularGlossiness.specularGlossinessTexture;
						pending.push( parser.assignTexture( materialParams, 'glossinessMap', specGlossMapDef ) );
						pending.push( parser.assignTexture( materialParams, 'specularMap', specGlossMapDef ) );

					}

					return Promise.all( pending );

				},
				createMaterial: function ( materialParams ) {

					var material = new GLTFMeshStandardSGMaterial( materialParams );
					material.fog = true;
					material.color = materialParams.color;
					material.map = materialParams.map === undefined ? null : materialParams.map;
					material.lightMap = null;
					material.lightMapIntensity = 1.0;
					material.aoMap = materialParams.aoMap === undefined ? null : materialParams.aoMap;
					material.aoMapIntensity = 1.0;
					material.emissive = materialParams.emissive;
					material.emissiveIntensity = 1.0;
					material.emissiveMap = materialParams.emissiveMap === undefined ? null : materialParams.emissiveMap;
					material.bumpMap = materialParams.bumpMap === undefined ? null : materialParams.bumpMap;
					material.bumpScale = 1;
					material.normalMap = materialParams.normalMap === undefined ? null : materialParams.normalMap;
					material.normalMapType = THREE.TangentSpaceNormalMap;
					if ( materialParams.normalScale ) material.normalScale = materialParams.normalScale;
					material.displacementMap = null;
					material.displacementScale = 1;
					material.displacementBias = 0;
					material.specularMap = materialParams.specularMap === undefined ? null : materialParams.specularMap;
					material.specular = materialParams.specular;
					material.glossinessMap = materialParams.glossinessMap === undefined ? null : materialParams.glossinessMap;
					material.glossiness = materialParams.glossiness;
					material.alphaMap = null;
					material.envMap = materialParams.envMap === undefined ? null : materialParams.envMap;
					material.envMapIntensity = 1.0;
					material.refractionRatio = 0.98;
					return material;

				}
			};

		}
		/**
	 * THREE.Mesh Quantization Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
	 */


		function GLTFMeshQuantizationExtension() {

			this.name = EXTENSIONS.KHR_MESH_QUANTIZATION;

		}
		/*********************************/

		/********** INTERPOLATION ********/

		/*********************************/
		// Spline Interpolation
		// Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation


		function GLTFCubicSplineInterpolant( parameterPositions, sampleValues, sampleSize, resultBuffer ) {

			THREE.Interpolant.call( this, parameterPositions, sampleValues, sampleSize, resultBuffer );

		}

		GLTFCubicSplineInterpolant.prototype = Object.create( THREE.Interpolant.prototype );
		GLTFCubicSplineInterpolant.prototype.constructor = GLTFCubicSplineInterpolant;

		GLTFCubicSplineInterpolant.prototype.copySampleValue_ = function ( index ) {

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

			for ( var i = 0; i !== valueSize; i ++ ) {

				result[ i ] = values[ offset + i ];

			}

			return result;

		};

		GLTFCubicSplineInterpolant.prototype.beforeStart_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_;
		GLTFCubicSplineInterpolant.prototype.afterEnd_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_;

		GLTFCubicSplineInterpolant.prototype.interpolate_ = function ( i1, t0, t, t1 ) {

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

			for ( var i = 0; i !== stride; i ++ ) {

				var p0 = values[ offset0 + i + stride ]; // splineVertex_k

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

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

				var m1 = values[ offset1 + i ] * td; // inTangent_k+1 * (t_k+1 - t_k)

				result[ i ] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;

			}

			return result;

		};
		/*********************************/

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

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

		/* CONSTANTS */


		var WEBGL_CONSTANTS = {
			FLOAT: 5126,
			//FLOAT_MAT2: 35674,
			FLOAT_MAT3: 35675,
			FLOAT_MAT4: 35676,
			FLOAT_VEC2: 35664,
			FLOAT_VEC3: 35665,
			FLOAT_VEC4: 35666,
			LINEAR: 9729,
			REPEAT: 10497,
			SAMPLER_2D: 35678,
			POINTS: 0,
			LINES: 1,
			LINE_LOOP: 2,
			LINE_STRIP: 3,
			TRIANGLES: 4,
			TRIANGLE_STRIP: 5,
			TRIANGLE_FAN: 6,
			UNSIGNED_BYTE: 5121,
			UNSIGNED_SHORT: 5123
		};
		var WEBGL_COMPONENT_TYPES = {
			5120: Int8Array,
			5121: Uint8Array,
			5122: Int16Array,
			5123: Uint16Array,
			5125: Uint32Array,
			5126: Float32Array
		};
		var WEBGL_FILTERS = {
			9728: THREE.NearestFilter,
			9729: THREE.LinearFilter,
			9984: THREE.NearestMipmapNearestFilter,
			9985: THREE.LinearMipmapNearestFilter,
			9986: THREE.NearestMipmapLinearFilter,
			9987: THREE.LinearMipmapLinearFilter
		};
		var WEBGL_WRAPPINGS = {
			33071: THREE.ClampToEdgeWrapping,
			33648: THREE.MirroredRepeatWrapping,
			10497: THREE.RepeatWrapping
		};
		var WEBGL_TYPE_SIZES = {
			'SCALAR': 1,
			'VEC2': 2,
			'VEC3': 3,
			'VEC4': 4,
			'MAT2': 4,
			'MAT3': 9,
			'MAT4': 16
		};
		var ATTRIBUTES = {
			POSITION: 'position',
			NORMAL: 'normal',
			TANGENT: 'tangent',
			TEXCOORD_0: 'uv',
			TEXCOORD_1: 'uv2',
			COLOR_0: 'color',
			WEIGHTS_0: 'skinWeight',
			JOINTS_0: 'skinIndex'
		};
		var PATH_PROPERTIES = {
			scale: 'scale',
			translation: 'position',
			rotation: 'quaternion',
			weights: 'morphTargetInfluences'
		};
		var INTERPOLATION = {
			CUBICSPLINE: undefined,
			// We use a custom interpolant (GLTFCubicSplineInterpolation) for CUBICSPLINE tracks. Each
			// keyframe track will be initialized with a default interpolation type, then modified.
			LINEAR: THREE.InterpolateLinear,
			STEP: THREE.InterpolateDiscrete
		};
		var ALPHA_MODES = {
			OPAQUE: 'OPAQUE',
			MASK: 'MASK',
			BLEND: 'BLEND'
		};
		/* UTILITY FUNCTIONS */

		function resolveURL( url, path ) {

			// Invalid URL
			if ( typeof url !== 'string' || url === '' ) return ''; // Host Relative URL

			if ( /^https?:\/\//i.test( path ) && /^\//.test( url ) ) {

				path = path.replace( /(^https?:\/\/[^\/]+).*/i, '$1' );

			} // Absolute URL http://,https://,//


			if ( /^(https?:)?\/\//i.test( url ) ) return url; // Data URI

			if ( /^data:.*,.*$/i.test( url ) ) return url; // Blob URL

			if ( /^blob:.*$/i.test( url ) ) return url; // Relative URL

			return path + url;

		}
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
	 */


		function createDefaultMaterial( cache ) {

			if ( cache[ 'DefaultMaterial' ] === undefined ) {

				cache[ 'DefaultMaterial' ] = new 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 ( var name in objectDef.extensions ) {

				if ( knownExtensions[ name ] === undefined ) {

					object.userData.gltfExtensions = object.userData.gltfExtensions || {};
					object.userData.gltfExtensions[ name ] = objectDef.extensions[ name ];

				}

			}

		}
		/**
	 * @param {Object3D|Material|BufferGeometry} object
	 * @param {GLTF.definition} gltfDef
	 */


		function assignExtrasToUserData( object, gltfDef ) {

			if ( gltfDef.extras !== undefined ) {

				if ( typeof gltfDef.extras === 'object' ) {

					Object.assign( object.userData, gltfDef.extras );

				} else {

					console.warn( 'THREE.GLTFLoader: Ignoring primitive type .extras, ' + gltfDef.extras );

				}

			}

		}
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
	 *
	 * @param {BufferGeometry} geometry
	 * @param {Array<GLTF.Target>} targets
	 * @param {GLTFParser} parser
	 * @return {Promise<BufferGeometry>}
	 */


		function addMorphTargets( geometry, targets, parser ) {

			var hasMorphPosition = false;
			var hasMorphNormal = false;

			for ( var i = 0, il = targets.length; i < il; i ++ ) {

				var target = targets[ i ];
				if ( target.POSITION !== undefined ) hasMorphPosition = true;
				if ( target.NORMAL !== undefined ) hasMorphNormal = true;
				if ( hasMorphPosition && hasMorphNormal ) break;

			}

			if ( ! hasMorphPosition && ! hasMorphNormal ) return Promise.resolve( geometry );
			var pendingPositionAccessors = [];
			var pendingNormalAccessors = [];

			for ( var i = 0, il = targets.length; i < il; i ++ ) {

				var target = targets[ i ];

				if ( hasMorphPosition ) {

					var pendingAccessor = target.POSITION !== undefined ? parser.getDependency( 'accessor', target.POSITION ) : geometry.attributes.position;
					pendingPositionAccessors.push( pendingAccessor );

				}

				if ( hasMorphNormal ) {

					var pendingAccessor = target.NORMAL !== undefined ? parser.getDependency( 'accessor', target.NORMAL ) : geometry.attributes.normal;
					pendingNormalAccessors.push( pendingAccessor );

				}

			}

			return Promise.all( [ Promise.all( pendingPositionAccessors ), Promise.all( pendingNormalAccessors ) ] ).then( function ( accessors ) {

				var morphPositions = accessors[ 0 ];
				var morphNormals = accessors[ 1 ];
				if ( hasMorphPosition ) geometry.morphAttributes.position = morphPositions;
				if ( hasMorphNormal ) geometry.morphAttributes.normal = morphNormals;
				geometry.morphTargetsRelative = true;
				return geometry;

			} );

		}
		/**
	 * @param {Mesh} mesh
	 * @param {GLTF.Mesh} meshDef
	 */


		function updateMorphTargets( mesh, meshDef ) {

			mesh.updateMorphTargets();

			if ( meshDef.weights !== undefined ) {

				for ( var i = 0, il = meshDef.weights.length; i < il; i ++ ) {

					mesh.morphTargetInfluences[ i ] = meshDef.weights[ i ];

				}

			} // .extras has user-defined data, so check that .extras.targetNames is an array.


			if ( meshDef.extras && Array.isArray( meshDef.extras.targetNames ) ) {

				var targetNames = meshDef.extras.targetNames;

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

					mesh.morphTargetDictionary = {};

					for ( var i = 0, il = targetNames.length; i < il; i ++ ) {

						mesh.morphTargetDictionary[ targetNames[ i ] ] = i;

					}

				} else {

					console.warn( 'THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names.' );

				}

			}

		}

		function createPrimitiveKey( primitiveDef ) {

			var dracoExtension = primitiveDef.extensions && primitiveDef.extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ];
			var geometryKey;

			if ( dracoExtension ) {

				geometryKey = 'draco:' + dracoExtension.bufferView + ':' + dracoExtension.indices + ':' + createAttributesKey( dracoExtension.attributes );

			} else {

				geometryKey = primitiveDef.indices + ':' + createAttributesKey( primitiveDef.attributes ) + ':' + primitiveDef.mode;

			}

			return geometryKey;

		}

		function createAttributesKey( attributes ) {

			var attributesKey = '';
			var keys = Object.keys( attributes ).sort();

			for ( var i = 0, il = keys.length; i < il; i ++ ) {

				attributesKey += keys[ i ] + ':' + attributes[ keys[ i ] ] + ';';

			}

			return attributesKey;

		}

		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.' );

			}

		}
		/* GLTF PARSER */


		function GLTFParser( json, options ) {

			this.json = json || {};
			this.extensions = {};
			this.plugins = {};
			this.options = options || {}; // loader object cache

			this.cache = new GLTFRegistry(); // associations between Three.js objects and glTF elements

			this.associations = new Map(); // THREE.BufferGeometry caching

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

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

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

			if ( typeof createImageBitmap !== 'undefined' && /Firefox/.test( navigator.userAgent ) === false ) {

				this.textureLoader = new THREE.ImageBitmapLoader( this.options.manager );

			} else {

				this.textureLoader = new THREE.TextureLoader( 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 );

			}

		}

		GLTFParser.prototype.setExtensions = function ( extensions ) {

			this.extensions = extensions;

		};

		GLTFParser.prototype.setPlugins = function ( plugins ) {

			this.plugins = plugins;

		};

		GLTFParser.prototype.parse = function ( onLoad, onError ) {

			var parser = this;
			var json = this.json;
			var extensions = this.extensions; // Clear the loader cache

			this.cache.removeAll(); // Mark the special nodes/meshes in json for efficient parse

			this._invokeAll( function ( ext ) {

				return ext._markDefs && ext._markDefs();

			} );

			Promise.all( this._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 ) {

				var result = {
					scene: dependencies[ 0 ][ json.scene || 0 ],
					scenes: dependencies[ 0 ],
					animations: dependencies[ 1 ],
					cameras: dependencies[ 2 ],
					asset: json.asset,
					parser: parser,
					userData: {}
				};
				addUnknownExtensionsToUserData( extensions, result, json );
				assignExtrasToUserData( result, json );
				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.
	 */


		GLTFParser.prototype._markDefs = function () {

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

			for ( var skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex ++ ) {

				var joints = skinDefs[ skinIndex ].joints;

				for ( var i = 0, il = joints.length; i < il; i ++ ) {

					nodeDefs[ joints[ i ] ].isBone = true;

				}

			} // Iterate over all nodes, marking references to shared resources,
			// as well as skeleton joints.


			for ( var nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex ++ ) {

				var nodeDef = nodeDefs[ nodeIndex ];

				if ( nodeDef.mesh !== undefined ) {

					this._addNodeRef( this.meshCache, nodeDef.mesh ); // Nothing in the mesh definition indicates whether it is
					// a 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.
	 */


		GLTFParser.prototype._addNodeRef = function ( cache, index ) {

			if ( index === undefined ) return;

			if ( cache.refs[ index ] === undefined ) {

				cache.refs[ index ] = cache.uses[ index ] = 0;

			}

			cache.refs[ index ] ++;

		};
		/** Returns a reference to a shared resource, cloning it if necessary. */


		GLTFParser.prototype._getNodeRef = function ( cache, index, object ) {

			if ( cache.refs[ index ] <= 1 ) return object;
			var ref = object.clone();
			ref.name += '_instance_' + cache.uses[ index ] ++;
			return ref;

		};

		GLTFParser.prototype._invokeOne = function ( func ) {

			var extensions = Object.values( this.plugins );
			extensions.push( this );

			for ( var i = 0; i < extensions.length; i ++ ) {

				var result = func( extensions[ i ] );
				if ( result ) return result;

			}

		};

		GLTFParser.prototype._invokeAll = function ( func ) {

			var extensions = Object.values( this.plugins );
			extensions.unshift( this );
			var pending = [];

			for ( var i = 0; i < extensions.length; i ++ ) {

				var result = func( extensions[ i ] );
				if ( result ) pending.push( result );

			}

			return pending;

		};
		/**
	 * Requests the specified dependency asynchronously, with caching.
	 * @param {string} type
	 * @param {number} index
	 * @return {Promise<Object3D|Material|THREE.Texture|AnimationClip|ArrayBuffer|Object>}
	 */


		GLTFParser.prototype.getDependency = function ( type, index ) {

			var cacheKey = type + ':' + index;
			var dependency = this.cache.get( cacheKey );

			if ( ! dependency ) {

				switch ( type ) {

					case 'scene':
						dependency = this.loadScene( index );
						break;

					case 'node':
						dependency = this.loadNode( index );
						break;

					case 'mesh':
						dependency = this._invokeOne( function ( ext ) {

							return ext.loadMesh && ext.loadMesh( index );

						} );
						break;

					case 'accessor':
						dependency = this.loadAccessor( index );
						break;

					case 'bufferView':
						dependency = this._invokeOne( function ( ext ) {

							return ext.loadBufferView && ext.loadBufferView( index );

						} );
						break;

					case 'buffer':
						dependency = this.loadBuffer( index );
						break;

					case 'material':
						dependency = this._invokeOne( function ( ext ) {

							return ext.loadMaterial && ext.loadMaterial( index );

						} );
						break;

					case 'texture':
						dependency = this._invokeOne( function ( ext ) {

							return ext.loadTexture && ext.loadTexture( index );

						} );
						break;

					case 'skin':
						dependency = this.loadSkin( index );
						break;

					case 'animation':
						dependency = this.loadAnimation( index );
						break;

					case 'camera':
						dependency = this.loadCamera( index );
						break;

					default:
						throw new Error( 'Unknown type: ' + type );

				}

				this.cache.add( cacheKey, dependency );

			}

			return dependency;

		};
		/**
	 * Requests all dependencies of the specified type asynchronously, with caching.
	 * @param {string} type
	 * @return {Promise<Array<Object>>}
	 */


		GLTFParser.prototype.getDependencies = function ( type ) {

			var dependencies = this.cache.get( type );

			if ( ! dependencies ) {

				var parser = this;
				var defs = this.json[ type + ( type === 'mesh' ? 'es' : 's' ) ] || [];
				dependencies = Promise.all( defs.map( function ( def, index ) {

					return parser.getDependency( type, index );

				} ) );
				this.cache.add( type, dependencies );

			}

			return dependencies;

		};
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
	 * @param {number} bufferIndex
	 * @return {Promise<ArrayBuffer>}
	 */


		GLTFParser.prototype.loadBuffer = function ( bufferIndex ) {

			var bufferDef = this.json.buffers[ bufferIndex ];
			var loader = this.fileLoader;

			if ( bufferDef.type && bufferDef.type !== 'arraybuffer' ) {

				throw new Error( 'THREE.GLTFLoader: ' + bufferDef.type + ' buffer type is not supported.' );

			} // If present, GLB container is required to be the first buffer.


			if ( bufferDef.uri === undefined && bufferIndex === 0 ) {

				return Promise.resolve( this.extensions[ EXTENSIONS.KHR_BINARY_GLTF ].body );

			}

			var options = this.options;
			return new Promise( function ( resolve, reject ) {

				loader.load( resolveURL( bufferDef.uri, options.path ), resolve, undefined, function () {

					reject( new Error( 'THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".' ) );

				} );

			} );

		};
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
	 * @param {number} bufferViewIndex
	 * @return {Promise<ArrayBuffer>}
	 */


		GLTFParser.prototype.loadBufferView = function ( bufferViewIndex ) {

			var bufferViewDef = this.json.bufferViews[ bufferViewIndex ];
			return this.getDependency( 'buffer', bufferViewDef.buffer ).then( function ( buffer ) {

				var byteLength = bufferViewDef.byteLength || 0;
				var byteOffset = bufferViewDef.byteOffset || 0;
				return buffer.slice( byteOffset, byteOffset + byteLength );

			} );

		};
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
	 * @param {number} accessorIndex
	 * @return {Promise<BufferAttribute|InterleavedBufferAttribute>}
	 */


		GLTFParser.prototype.loadAccessor = function ( accessorIndex ) {

			var parser = this;
			var json = this.json;
			var accessorDef = this.json.accessors[ accessorIndex ];

			if ( accessorDef.bufferView === undefined && accessorDef.sparse === undefined ) {

				// Ignore empty accessors, which may be used to declare runtime
				// information about attributes coming from another source (e.g. Draco
				// compression extension).
				return Promise.resolve( null );

			}

			var pendingBufferViews = [];

			if ( accessorDef.bufferView !== undefined ) {

				pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.bufferView ) );

			} else {

				pendingBufferViews.push( null );

			}

			if ( accessorDef.sparse !== undefined ) {

				pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.sparse.indices.bufferView ) );
				pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.sparse.values.bufferView ) );

			}

			return Promise.all( pendingBufferViews ).then( function ( bufferViews ) {

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

				var elementBytes = TypedArray.BYTES_PER_ELEMENT;
				var itemBytes = elementBytes * itemSize;
				var byteOffset = accessorDef.byteOffset || 0;
				var byteStride = accessorDef.bufferView !== undefined ? json.bufferViews[ accessorDef.bufferView ].byteStride : undefined;
				var normalized = accessorDef.normalized === true;
				var array, bufferAttribute; // The buffer is not interleaved if the stride is the item size in bytes.

				if ( byteStride && byteStride !== itemBytes ) {

					// Each "slice" of the buffer, as defined by 'count' elements of 'byteStride' bytes, gets its own THREE.InterleavedBuffer
					// This makes sure that IBA.count reflects accessor.count properly
					var ibSlice = Math.floor( byteOffset / byteStride );
					var ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType + ':' + ibSlice + ':' + accessorDef.count;
					var ib = parser.cache.get( ibCacheKey );

					if ( ! ib ) {

						array = new TypedArray( bufferView, ibSlice * byteStride, accessorDef.count * byteStride / elementBytes ); // Integer parameters to IB/IBA are in array elements, not bytes.

						ib = new 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 ) {

					var itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
					var TypedArrayIndices = WEBGL_COMPONENT_TYPES[ accessorDef.sparse.indices.componentType ];
					var byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
					var byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;
					var sparseIndices = new TypedArrayIndices( bufferViews[ 1 ], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices );
					var sparseValues = new TypedArray( bufferViews[ 2 ], byteOffsetValues, accessorDef.sparse.count * itemSize );

					if ( bufferView !== null ) {

						// Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
						bufferAttribute = new THREE.BufferAttribute( bufferAttribute.array.slice(), bufferAttribute.itemSize, bufferAttribute.normalized );

					}

					for ( var i = 0, il = sparseIndices.length; i < il; i ++ ) {

						var index = sparseIndices[ i ];
						bufferAttribute.setX( index, sparseValues[ i * itemSize ] );
						if ( itemSize >= 2 ) bufferAttribute.setY( index, sparseValues[ i * itemSize + 1 ] );
						if ( itemSize >= 3 ) bufferAttribute.setZ( index, sparseValues[ i * itemSize + 2 ] );
						if ( itemSize >= 4 ) bufferAttribute.setW( index, sparseValues[ i * itemSize + 3 ] );
						if ( itemSize >= 5 ) throw new Error( 'THREE.GLTFLoader: Unsupported itemSize in sparse THREE.BufferAttribute.' );

					}

				}

				return bufferAttribute;

			} );

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


		GLTFParser.prototype.loadTexture = function ( textureIndex ) {

			var json = this.json;
			var options = this.options;
			var textureDef = json.textures[ textureIndex ];
			var source = json.images[ textureDef.source ];
			var loader = this.textureLoader;

			if ( source.uri ) {

				var handler = options.manager.getHandler( source.uri );
				if ( handler !== null ) loader = handler;

			}

			return this.loadTextureImage( textureIndex, source, loader );

		};

		GLTFParser.prototype.loadTextureImage = function ( textureIndex, source, loader ) {

			var parser = this;
			var json = this.json;
			var options = this.options;
			var textureDef = json.textures[ textureIndex ];
			var URL = self.URL || self.webkitURL;
			var sourceURI = source.uri;
			var isObjectURL = false;
			var hasAlpha = true;
			if ( source.mimeType === 'image/jpeg' ) hasAlpha = false;

			if ( source.bufferView !== undefined ) {

				// Load binary image data from bufferView, if provided.
				sourceURI = parser.getDependency( 'bufferView', source.bufferView ).then( function ( bufferView ) {

					if ( source.mimeType === 'image/png' ) {

						// Inspect the PNG 'IHDR' chunk to determine whether the image could have an
						// alpha channel. This check is conservative — the image could have an alpha
						// channel with all values == 1, and the indexed type (colorType == 3) only
						// sometimes contains alpha.
						//
						// https://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header
						var colorType = new DataView( bufferView, 25, 1 ).getUint8( 0, false );
						hasAlpha = colorType === 6 || colorType === 4 || colorType === 3;

					}

					isObjectURL = true;
					var blob = new Blob( [ bufferView ], {
						type: source.mimeType
					} );
					sourceURI = URL.createObjectURL( blob );
					return sourceURI;

				} );

			} else if ( source.uri === undefined ) {

				throw new Error( 'THREE.GLTFLoader: Image ' + textureIndex + ' is missing URI and bufferView' );

			}

			return Promise.resolve( sourceURI ).then( function ( sourceURI ) {

				return new Promise( function ( resolve, reject ) {

					var onLoad = resolve;

					if ( loader.isImageBitmapLoader === true ) {

						onLoad = function ( imageBitmap ) {

							resolve( new THREE.CanvasTexture( imageBitmap ) );

						};

					}

					loader.load( resolveURL( sourceURI, options.path ), onLoad, undefined, reject );

				} );

			} ).then( function ( texture ) {

				// Clean up resources and configure Texture.
				if ( isObjectURL === true ) {

					URL.revokeObjectURL( sourceURI );

				}

				texture.flipY = false;
				if ( textureDef.name ) texture.name = textureDef.name; // When there is definitely no alpha channel in the texture, set THREE.RGBFormat to save space.

				if ( ! hasAlpha ) texture.format = THREE.RGBFormat;
				var samplers = json.samplers || {};
				var 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, {
					type: 'textures',
					index: textureIndex
				} );
				return texture;

			} );

		};
		/**
	 * Asynchronously assigns a texture to the given material parameters.
	 * @param {Object} materialParams
	 * @param {string} mapName
	 * @param {Object} mapDef
	 * @return {Promise}
	 */


		GLTFParser.prototype.assignTexture = function ( materialParams, mapName, mapDef ) {

			var parser = this;
			return this.getDependency( 'texture', mapDef.index ).then( function ( texture ) {

				// Materials sample aoMap from UV set 1 and other maps from UV set 0 - this can't be configured
				// However, we will copy UV set 0 to UV set 1 on demand for aoMap
				if ( mapDef.texCoord !== undefined && mapDef.texCoord != 0 && ! ( mapName === 'aoMap' && mapDef.texCoord == 1 ) ) {

					console.warn( 'THREE.GLTFLoader: Custom UV set ' + mapDef.texCoord + ' for texture ' + mapName + ' not yet supported.' );

				}

				if ( parser.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ] ) {

					var transform = mapDef.extensions !== undefined ? mapDef.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ] : undefined;

					if ( transform ) {

						var gltfReference = parser.associations.get( texture );
						texture = parser.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ].extendTexture( texture, transform );
						parser.associations.set( texture, gltfReference );

					}

				}

				materialParams[ mapName ] = texture;

			} );

		};
		/**
	 * Assigns final material to a 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.
	 */


		GLTFParser.prototype.assignFinalMaterial = function ( mesh ) {

			var geometry = mesh.geometry;
			var material = mesh.material;
			var useVertexTangents = geometry.attributes.tangent !== undefined;
			var useVertexColors = geometry.attributes.color !== undefined;
			var useFlatShading = geometry.attributes.normal === undefined;
			var useSkinning = mesh.isSkinnedMesh === true;
			var useMorphTargets = Object.keys( geometry.morphAttributes ).length > 0;
			var useMorphNormals = useMorphTargets && geometry.morphAttributes.normal !== undefined;

			if ( mesh.isPoints ) {

				var cacheKey = 'PointsMaterial:' + material.uuid;
				var pointsMaterial = this.cache.get( cacheKey );

				if ( ! pointsMaterial ) {

					pointsMaterial = new 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 ) {

				var cacheKey = 'LineBasicMaterial:' + material.uuid;
				var 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 ( useVertexTangents || useVertexColors || useFlatShading || useSkinning || useMorphTargets ) {

				var cacheKey = 'ClonedMaterial:' + material.uuid + ':';
				if ( material.isGLTFSpecularGlossinessMaterial ) cacheKey += 'specular-glossiness:';
				if ( useSkinning ) cacheKey += 'skinning:';
				if ( useVertexTangents ) cacheKey += 'vertex-tangents:';
				if ( useVertexColors ) cacheKey += 'vertex-colors:';
				if ( useFlatShading ) cacheKey += 'flat-shading:';
				if ( useMorphTargets ) cacheKey += 'morph-targets:';
				if ( useMorphNormals ) cacheKey += 'morph-normals:';
				var cachedMaterial = this.cache.get( cacheKey );

				if ( ! cachedMaterial ) {

					cachedMaterial = material.clone();
					if ( useSkinning ) cachedMaterial.skinning = true;
					if ( useVertexColors ) cachedMaterial.vertexColors = true;
					if ( useFlatShading ) cachedMaterial.flatShading = true;
					if ( useMorphTargets ) cachedMaterial.morphTargets = true;
					if ( useMorphNormals ) cachedMaterial.morphNormals = true;

					if ( useVertexTangents ) {

						cachedMaterial.vertexTangents = true; // 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;

		};

		GLTFParser.prototype.getMaterialType = function ( ) {

			return THREE.MeshStandardMaterial;

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


		GLTFParser.prototype.loadMaterial = function ( materialIndex ) {

			var parser = this;
			var json = this.json;
			var extensions = this.extensions;
			var materialDef = json.materials[ materialIndex ];
			var materialType;
			var materialParams = {};
			var materialExtensions = materialDef.extensions || {};
			var pending = [];

			if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ] ) {

				var sgExtension = extensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ];
				materialType = sgExtension.getMaterialType();
				pending.push( sgExtension.extendParams( materialParams, materialDef, parser ) );

			} else if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_UNLIT ] ) {

				var kmuExtension = extensions[ EXTENSIONS.KHR_MATERIALS_UNLIT ];
				materialType = kmuExtension.getMaterialType();
				pending.push( kmuExtension.extendParams( materialParams, materialDef, parser ) );

			} else {

				// Specification:
				// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material
				var metallicRoughness = materialDef.pbrMetallicRoughness || {};
				materialParams.color = new THREE.Color( 1.0, 1.0, 1.0 );
				materialParams.opacity = 1.0;

				if ( Array.isArray( metallicRoughness.baseColorFactor ) ) {

					var array = metallicRoughness.baseColorFactor;
					materialParams.color.fromArray( array );
					materialParams.opacity = array[ 3 ];

				}

				if ( metallicRoughness.baseColorTexture !== undefined ) {

					pending.push( parser.assignTexture( materialParams, 'map', metallicRoughness.baseColorTexture ) );

				}

				materialParams.metalness = metallicRoughness.metallicFactor !== undefined ? metallicRoughness.metallicFactor : 1.0;
				materialParams.roughness = metallicRoughness.roughnessFactor !== undefined ? metallicRoughness.roughnessFactor : 1.0;

				if ( metallicRoughness.metallicRoughnessTexture !== undefined ) {

					pending.push( parser.assignTexture( materialParams, 'metalnessMap', metallicRoughness.metallicRoughnessTexture ) );
					pending.push( parser.assignTexture( materialParams, 'roughnessMap', metallicRoughness.metallicRoughnessTexture ) );

				}

				materialType = this._invokeOne( function ( ext ) {

					return ext.getMaterialType && ext.getMaterialType( materialIndex );

				} );
				pending.push( Promise.all( this._invokeAll( function ( ext ) {

					return ext.extendMaterialParams && ext.extendMaterialParams( materialIndex, materialParams );

				} ) ) );

			}

			if ( materialDef.doubleSided === true ) {

				materialParams.side = THREE.DoubleSide;

			}

			var alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;

			if ( alphaMode === ALPHA_MODES.BLEND ) {

				materialParams.transparent = true; // See: https://github.com/mrdoob/three.js/issues/17706

				materialParams.depthWrite = false;

			} else {

				materialParams.transparent = false;

				if ( alphaMode === ALPHA_MODES.MASK ) {

					materialParams.alphaTest = materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;

				}

			}

			if ( materialDef.normalTexture !== undefined && materialType !== THREE.MeshBasicMaterial ) {

				pending.push( parser.assignTexture( materialParams, 'normalMap', materialDef.normalTexture ) ); // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995

				materialParams.normalScale = new THREE.Vector2( 1, - 1 );

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

					materialParams.normalScale.set( materialDef.normalTexture.scale, - materialDef.normalTexture.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 ) );

			}

			return Promise.all( pending ).then( function () {

				var material;

				if ( materialType === GLTFMeshStandardSGMaterial ) {

					material = extensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ].createMaterial( materialParams );

				} else {

					material = new materialType( materialParams );

				}

				if ( materialDef.name ) material.name = materialDef.name; // baseColorTexture, emissiveTexture, and specularGlossinessTexture use sRGB encoding.

				if ( material.map ) material.map.encoding = THREE.sRGBEncoding;
				if ( material.emissiveMap ) material.emissiveMap.encoding = THREE.sRGBEncoding;
				assignExtrasToUserData( material, materialDef );
				parser.associations.set( material, {
					type: 'materials',
					index: materialIndex
				} );
				if ( materialDef.extensions ) addUnknownExtensionsToUserData( extensions, material, materialDef );
				return material;

			} );

		};
		/** When THREE.Object3D instances are targeted by animation, they need unique names. */


		GLTFParser.prototype.createUniqueName = function ( originalName ) {

			var sanitizedName = THREE.PropertyBinding.sanitizeNodeName( originalName || '' );
			var name = sanitizedName;

			for ( var i = 1; this.nodeNamesUsed[ name ]; ++ i ) {

				name = sanitizedName + '_' + i;

			}

			this.nodeNamesUsed[ name ] = true;
			return name;

		};
		/**
	 * @param {BufferGeometry} geometry
	 * @param {GLTF.Primitive} primitiveDef
	 * @param {GLTFParser} parser
	 */


		function computeBounds( geometry, primitiveDef, parser ) {

			var attributes = primitiveDef.attributes;
			var box = new THREE.Box3();

			if ( attributes.POSITION !== undefined ) {

				var accessor = parser.json.accessors[ attributes.POSITION ];
				var min = accessor.min;
				var max = accessor.max; // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

				if ( min !== undefined && max !== undefined ) {

					box.set( new THREE.Vector3( min[ 0 ], min[ 1 ], min[ 2 ] ), new THREE.Vector3( max[ 0 ], max[ 1 ], max[ 2 ] ) );

					if ( accessor.normalized ) {

						var 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;

			}

			var targets = primitiveDef.targets;

			if ( targets !== undefined ) {

				var maxDisplacement = new THREE.Vector3();
				var vector = new THREE.Vector3();

				for ( var i = 0, il = targets.length; i < il; i ++ ) {

					var target = targets[ i ];

					if ( target.POSITION !== undefined ) {

						var accessor = parser.json.accessors[ target.POSITION ];
						var min = accessor.min;
						var max = accessor.max; // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

						if ( min !== undefined && max !== undefined ) {

							// we need to get max of absolute components because target weight is [-1,1]
							vector.setX( Math.max( Math.abs( min[ 0 ] ), Math.abs( max[ 0 ] ) ) );
							vector.setY( Math.max( Math.abs( min[ 1 ] ), Math.abs( max[ 1 ] ) ) );
							vector.setZ( Math.max( Math.abs( min[ 2 ] ), Math.abs( max[ 2 ] ) ) );

							if ( accessor.normalized ) {

								var 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;
			var 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 ) {

			var attributes = primitiveDef.attributes;
			var pending = [];

			function assignAttributeAccessor( accessorIndex, attributeName ) {

				return parser.getDependency( 'accessor', accessorIndex ).then( function ( accessor ) {

					geometry.setAttribute( attributeName, accessor );

				} );

			}

			for ( var gltfAttributeName in attributes ) {

				var threeAttributeName = ATTRIBUTES[ gltfAttributeName ] || gltfAttributeName.toLowerCase(); // Skip attributes already provided by e.g. Draco extension.

				if ( threeAttributeName in geometry.attributes ) continue;
				pending.push( assignAttributeAccessor( attributes[ gltfAttributeName ], threeAttributeName ) );

			}

			if ( primitiveDef.indices !== undefined && ! geometry.index ) {

				var accessor = parser.getDependency( 'accessor', primitiveDef.indices ).then( function ( accessor ) {

					geometry.setIndex( accessor );

				} );
				pending.push( accessor );

			}

			assignExtrasToUserData( geometry, primitiveDef );
			computeBounds( geometry, primitiveDef, parser );
			return Promise.all( pending ).then( function () {

				return primitiveDef.targets !== undefined ? addMorphTargets( geometry, primitiveDef.targets, parser ) : geometry;

			} );

		}
		/**
	 * @param {BufferGeometry} geometry
	 * @param {Number} drawMode
	 * @return {BufferGeometry}
	 */


		function toTrianglesDrawMode( geometry, drawMode ) {

			var index = geometry.getIndex(); // generate index if not present

			if ( index === null ) {

				var indices = [];
				var position = geometry.getAttribute( 'position' );

				if ( position !== undefined ) {

					for ( var i = 0; i < position.count; i ++ ) {

						indices.push( i );

					}

					geometry.setIndex( indices );
					index = geometry.getIndex();

				} else {

					console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.' );
					return geometry;

				}

			} //


			var numberOfTriangles = index.count - 2;
			var newIndices = [];

			if ( drawMode === THREE.TriangleFanDrawMode ) {

				// gl.TRIANGLE_FAN
				for ( var i = 1; i <= numberOfTriangles; i ++ ) {

					newIndices.push( index.getX( 0 ) );
					newIndices.push( index.getX( i ) );
					newIndices.push( index.getX( i + 1 ) );

				}

			} else {

				// gl.TRIANGLE_STRIP
				for ( var i = 0; i < numberOfTriangles; i ++ ) {

					if ( i % 2 === 0 ) {

						newIndices.push( index.getX( i ) );
						newIndices.push( index.getX( i + 1 ) );
						newIndices.push( index.getX( i + 2 ) );

					} else {

						newIndices.push( index.getX( i + 2 ) );
						newIndices.push( index.getX( i + 1 ) );
						newIndices.push( index.getX( i ) );

					}

				}

			}

			if ( newIndices.length / 3 !== numberOfTriangles ) {

				console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles.' );

			} // build final geometry


			var newGeometry = geometry.clone();
			newGeometry.setIndex( newIndices );
			return newGeometry;

		}
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
	 *
	 * Creates BufferGeometries from primitives.
	 *
	 * @param {Array<GLTF.Primitive>} primitives
	 * @return {Promise<Array<BufferGeometry>>}
	 */


		GLTFParser.prototype.loadGeometries = function ( primitives ) {

			var parser = this;
			var extensions = this.extensions;
			var cache = this.primitiveCache;

			function createDracoPrimitive( primitive ) {

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

					return addPrimitiveAttributes( geometry, primitive, parser );

				} );

			}

			var pending = [];

			for ( var i = 0, il = primitives.length; i < il; i ++ ) {

				var primitive = primitives[ i ];
				var cacheKey = createPrimitiveKey( primitive ); // See if we've already created this geometry

				var cached = cache[ cacheKey ];

				if ( cached ) {

					// Use the cached geometry if it exists
					pending.push( cached.promise );

				} else {

					var geometryPromise;

					if ( primitive.extensions && primitive.extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ] ) {

						// Use DRACO geometry if available
						geometryPromise = createDracoPrimitive( primitive );

					} else {

						// Otherwise create a new geometry
						geometryPromise = addPrimitiveAttributes( new 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>}
	 */


		GLTFParser.prototype.loadMesh = function ( meshIndex ) {

			var parser = this;
			var json = this.json;
			var extensions = this.extensions;
			var meshDef = json.meshes[ meshIndex ];
			var primitives = meshDef.primitives;
			var pending = [];

			for ( var i = 0, il = primitives.length; i < il; i ++ ) {

				var material = primitives[ i ].material === undefined ? createDefaultMaterial( this.cache ) : this.getDependency( 'material', primitives[ i ].material );
				pending.push( material );

			}

			pending.push( parser.loadGeometries( primitives ) );
			return Promise.all( pending ).then( function ( results ) {

				var materials = results.slice( 0, results.length - 1 );
				var geometries = results[ results.length - 1 ];
				var meshes = [];

				for ( var i = 0, il = geometries.length; i < il; i ++ ) {

					var geometry = geometries[ i ];
					var primitive = primitives[ i ]; // 1. create THREE.Mesh

					var mesh;
					var material = materials[ i ];

					if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLES || primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP || primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN || primitive.mode === undefined ) {

						// .isSkinnedMesh isn't in glTF spec. See ._markDefs()
						mesh = meshDef.isSkinnedMesh === true ? new 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 );

				}

				if ( meshes.length === 1 ) {

					return meshes[ 0 ];

				}

				var group = new THREE.Group();

				for ( var i = 0, il = meshes.length; i < il; i ++ ) {

					group.add( meshes[ i ] );

				}

				return group;

			} );

		};
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
	 * @param {number} cameraIndex
	 * @return {Promise<THREE.Camera>}
	 */


		GLTFParser.prototype.loadCamera = function ( cameraIndex ) {

			var camera;
			var cameraDef = this.json.cameras[ cameraIndex ];
			var params = cameraDef[ cameraDef.type ];

			if ( ! params ) {

				console.warn( 'THREE.GLTFLoader: Missing camera parameters.' );
				return;

			}

			if ( cameraDef.type === 'perspective' ) {

				camera = new THREE.PerspectiveCamera( THREE.MathUtils.radToDeg( params.yfov ), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6 );

			} else if ( cameraDef.type === 'orthographic' ) {

				camera = new THREE.OrthographicCamera( - params.xmag, params.xmag, params.ymag, - params.ymag, params.znear, params.zfar );

			}

			if ( cameraDef.name ) camera.name = this.createUniqueName( cameraDef.name );
			assignExtrasToUserData( camera, cameraDef );
			return Promise.resolve( camera );

		};
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
	 * @param {number} skinIndex
	 * @return {Promise<Object>}
	 */


		GLTFParser.prototype.loadSkin = function ( skinIndex ) {

			var skinDef = this.json.skins[ skinIndex ];
			var skinEntry = {
				joints: skinDef.joints
			};

			if ( skinDef.inverseBindMatrices === undefined ) {

				return Promise.resolve( skinEntry );

			}

			return this.getDependency( 'accessor', skinDef.inverseBindMatrices ).then( function ( accessor ) {

				skinEntry.inverseBindMatrices = accessor;
				return skinEntry;

			} );

		};
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
	 * @param {number} animationIndex
	 * @return {Promise<AnimationClip>}
	 */


		GLTFParser.prototype.loadAnimation = function ( animationIndex ) {

			var json = this.json;
			var animationDef = json.animations[ animationIndex ];
			var pendingNodes = [];
			var pendingInputAccessors = [];
			var pendingOutputAccessors = [];
			var pendingSamplers = [];
			var pendingTargets = [];

			for ( var i = 0, il = animationDef.channels.length; i < il; i ++ ) {

				var channel = animationDef.channels[ i ];
				var sampler = animationDef.samplers[ channel.sampler ];
				var target = channel.target;
				var name = target.node !== undefined ? target.node : target.id; // NOTE: target.id is deprecated.

				var input = animationDef.parameters !== undefined ? animationDef.parameters[ sampler.input ] : sampler.input;
				var output = animationDef.parameters !== undefined ? animationDef.parameters[ sampler.output ] : sampler.output;
				pendingNodes.push( this.getDependency( 'node', name ) );
				pendingInputAccessors.push( this.getDependency( 'accessor', input ) );
				pendingOutputAccessors.push( this.getDependency( 'accessor', output ) );
				pendingSamplers.push( sampler );
				pendingTargets.push( target );

			}

			return Promise.all( [ Promise.all( pendingNodes ), Promise.all( pendingInputAccessors ), Promise.all( pendingOutputAccessors ), Promise.all( pendingSamplers ), Promise.all( pendingTargets ) ] ).then( function ( dependencies ) {

				var nodes = dependencies[ 0 ];
				var inputAccessors = dependencies[ 1 ];
				var outputAccessors = dependencies[ 2 ];
				var samplers = dependencies[ 3 ];
				var targets = dependencies[ 4 ];
				var tracks = [];

				for ( var i = 0, il = nodes.length; i < il; i ++ ) {

					var node = nodes[ i ];
					var inputAccessor = inputAccessors[ i ];
					var outputAccessor = outputAccessors[ i ];
					var sampler = samplers[ i ];
					var target = targets[ i ];
					if ( node === undefined ) continue;
					node.updateMatrix();
					node.matrixAutoUpdate = true;
					var TypedKeyframeTrack;

					switch ( PATH_PROPERTIES[ target.path ] ) {

						case PATH_PROPERTIES.weights:
							TypedKeyframeTrack = THREE.NumberKeyframeTrack;
							break;

						case PATH_PROPERTIES.rotation:
							TypedKeyframeTrack = THREE.QuaternionKeyframeTrack;
							break;

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

					}

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

					if ( PATH_PROPERTIES[ target.path ] === PATH_PROPERTIES.weights ) {

						// Node may be a THREE.Group (glTF mesh with several primitives) or a THREE.Mesh.
						node.traverse( function ( object ) {

							if ( object.isMesh === true && object.morphTargetInfluences ) {

								targetNames.push( object.name ? object.name : object.uuid );

							}

						} );

					} else {

						targetNames.push( targetName );

					}

					var outputArray = outputAccessor.array;

					if ( outputAccessor.normalized ) {

						var scale = getNormalizedComponentScale( outputArray.constructor );
						var scaled = new Float32Array( outputArray.length );

						for ( var j = 0, jl = outputArray.length; j < jl; j ++ ) {

							scaled[ j ] = outputArray[ j ] * scale;

						}

						outputArray = scaled;

					}

					for ( var j = 0, jl = targetNames.length; j < jl; j ++ ) {

						var track = new TypedKeyframeTrack( targetNames[ j ] + '.' + PATH_PROPERTIES[ target.path ], inputAccessor.array, outputArray, interpolation ); // Override interpolation with custom factory method.

						if ( sampler.interpolation === 'CUBICSPLINE' ) {

							track.createInterpolant = function InterpolantFactoryMethodGLTFCubicSpline( result ) {

								// A CUBICSPLINE keyframe in glTF has three output values for each input value,
								// representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
								// must be divided by three to get the interpolant's sampleSize argument.
								return new GLTFCubicSplineInterpolant( this.times, this.values, this.getValueSize() / 3, result );

							}; // Mark as CUBICSPLINE. `track.getInterpolation()` doesn't support custom interpolants.


							track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;

						}

						tracks.push( track );

					}

				}

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

			} );

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


		GLTFParser.prototype.loadNode = function ( nodeIndex ) {

			var json = this.json;
			var extensions = this.extensions;
			var parser = this;
			var nodeDef = json.nodes[ nodeIndex ]; // reserve node's name before its dependencies, so the root has the intended name.

			var nodeName = nodeDef.name ? parser.createUniqueName( nodeDef.name ) : '';
			return function () {

				var pending = [];

				if ( nodeDef.mesh !== undefined ) {

					pending.push( parser.getDependency( 'mesh', nodeDef.mesh ).then( function ( mesh ) {

						var node = parser._getNodeRef( parser.meshCache, nodeDef.mesh, mesh ); // if weights are provided on the node, override weights on the mesh.


						if ( nodeDef.weights !== undefined ) {

							node.traverse( function ( o ) {

								if ( ! o.isMesh ) return;

								for ( var i = 0, il = nodeDef.weights.length; i < il; i ++ ) {

									o.morphTargetInfluences[ i ] = nodeDef.weights[ i ];

								}

							} );

						}

						return node;

					} ) );

				}

				if ( nodeDef.camera !== undefined ) {

					pending.push( parser.getDependency( 'camera', nodeDef.camera ).then( function ( camera ) {

						return parser._getNodeRef( parser.cameraCache, nodeDef.camera, camera );

					} ) );

				}

				parser._invokeAll( function ( ext ) {

					return ext.createNodeAttachment && ext.createNodeAttachment( nodeIndex );

				} ).forEach( function ( promise ) {

					pending.push( promise );

				} );

				return Promise.all( pending );

			}().then( function ( objects ) {

				var node; // .isBone isn't in glTF spec. See ._markDefs

				if ( nodeDef.isBone === true ) {

					node = new 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 ( var i = 0, il = objects.length; i < il; i ++ ) {

						node.add( objects[ i ] );

					}

				}

				if ( nodeDef.name ) {

					node.userData.name = nodeDef.name;
					node.name = nodeName;

				}

				assignExtrasToUserData( node, nodeDef );
				if ( nodeDef.extensions ) addUnknownExtensionsToUserData( extensions, node, nodeDef );

				if ( nodeDef.matrix !== undefined ) {

					var matrix = new 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 );

					}

				}

				parser.associations.set( node, {
					type: 'nodes',
					index: nodeIndex
				} );
				return node;

			} );

		};
		/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
	 * @param {number} sceneIndex
	 * @return {Promise<Group>}
	 */


		GLTFParser.prototype.loadScene = function () {

			// scene node hierachy builder
			function buildNodeHierachy( nodeId, parentObject, json, parser ) {

				var nodeDef = json.nodes[ nodeId ];
				return parser.getDependency( 'node', nodeId ).then( function ( node ) {

					if ( nodeDef.skin === undefined ) return node; // build skeleton here as well

					var skinEntry;
					return parser.getDependency( 'skin', nodeDef.skin ).then( function ( skin ) {

						skinEntry = skin;
						var pendingJoints = [];

						for ( var i = 0, il = skinEntry.joints.length; i < il; i ++ ) {

							pendingJoints.push( parser.getDependency( 'node', skinEntry.joints[ i ] ) );

						}

						return Promise.all( pendingJoints );

					} ).then( function ( jointNodes ) {

						node.traverse( function ( mesh ) {

							if ( ! mesh.isMesh ) return;
							var bones = [];
							var boneInverses = [];

							for ( var j = 0, jl = jointNodes.length; j < jl; j ++ ) {

								var jointNode = jointNodes[ j ];

								if ( jointNode ) {

									bones.push( jointNode );
									var mat = new THREE.Matrix4();

									if ( skinEntry.inverseBindMatrices !== undefined ) {

										mat.fromArray( skinEntry.inverseBindMatrices.array, j * 16 );

									}

									boneInverses.push( mat );

								} else {

									console.warn( 'THREE.GLTFLoader: Joint "%s" could not be found.', skinEntry.joints[ j ] );

								}

							}

							mesh.bind( new THREE.Skeleton( bones, boneInverses ), mesh.matrixWorld );

						} );
						return node;

					} );

				} ).then( function ( node ) {

					// build node hierachy
					parentObject.add( node );
					var pending = [];

					if ( nodeDef.children ) {

						var children = nodeDef.children;

						for ( var i = 0, il = children.length; i < il; i ++ ) {

							var child = children[ i ];
							pending.push( buildNodeHierachy( child, node, json, parser ) );

						}

					}

					return Promise.all( pending );

				} );

			}

			return function loadScene( sceneIndex ) {

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

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

				for ( var i = 0, il = nodeIds.length; i < il; i ++ ) {

					pending.push( buildNodeHierachy( nodeIds[ i ], scene, json, parser ) );

				}

				return Promise.all( pending ).then( function () {

					return scene;

				} );

			};

		}();

		return GLTFLoader;

	}();

	THREE.GLTFLoader = GLTFLoader;

} )();