three.js源码翻译及案例(五)-GLTFLoader.js

写在前面

Three中的加载脚本很多，但是核心思想是差不多的，就是文件用文件解析器加载，图片用图片解析器加载，然后json转换为对象，但是由于gltf格式可以自己编辑所以有的源码参考意义不大，glb及拓展材质都没用上就还没有翻译，以后可能会补上。

源码位置

• 该源码位置在three.js源码examples\js\loaders文件夹下

源码翻译

/**
 * @author Rich Tibbett / https://github.com/richtr
 * @author mrdoob / http://mrdoob.com/
 * @author Tony Parisi / http://www.tonyparisi.com/
 * @author Takahiro / https://github.com/takahirox
 * @author Don McCurdy / https://www.donmccurdy.com
 */
/*
 * 本文档为Three.js翻译文档，如有任何疑问请联系:
 * [email protected]
 */
THREE.GLTFLoader = (function () {

	/**
	 * @description GLTF的加载文件
	 * @date 2019-04-16
	 * @param {*} manager 加载管理器
	 */
	function GLTFLoader(manager) {
		//新建一个加载管理器
		this.manager = (manager !== undefined) ? manager : THREE.DefaultLoadingManager;
		//设置点云加载器为空，接收draco文件的
		this.dracoLoader = null;
	}

	GLTFLoader.prototype = {

		constructor: GLTFLoader,

		crossOrigin: 'anonymous',
		/**
		 * @description gltf加载方法
		 * @date 2019-04-17
		 * @param {*} url url的地址
		 * @param {*} onLoad	加载方法
		 * @param {*} onProgress	加载过程中调用的方法
		 * @param {*} onError	加载失败调用的方法
		 */
		load: function (url, onLoad, onProgress, onError) {
			//获得this	
			var scope = this;
			//创建一个资源路径
			var resourcePath;
			//获得路径
			if (this.resourcePath !== undefined) {

				resourcePath = this.resourcePath;

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

				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.
			//加载管理器开始监听url
			scope.manager.itemStart(url);
			//加载失败的方法
			var _onError = function (e) {

				if (onError) {

					onError(e);

				} else {

					console.error(e);

				}

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

			};
			//新建一个文件加载器
			var loader = new THREE.FileLoader(scope.manager);
			//设置路径
			loader.setPath(this.path);
			//设置响应类型，响应类型在FileLoader有写
			loader.setResponseType('arraybuffer');
			//开始加载资源，有两个参数，一个是url一个是加载成功的数据方法
			loader.load(url, function (data) {

				try {
					//尝试去加载资源
					scope.parse(data, resourcePath, function (gltf) {
						//返回的gltf是可以直接导入到场景的gltf
						onLoad(gltf);
						//结束管理器的监听
						scope.manager.itemEnd(url);

					}, _onError);

				} catch (e) {

					_onError(e);

				}

			}, onProgress, _onError);

		},

		/**
		 * @description 应该是设置gltf的类型
		 * @date 2019-04-17
		 * @param {*} value
		 * @returns 
		 */
		setCrossOrigin: function (value) {

			this.crossOrigin = value;
			return this;

		},

		/**
		 * @description 设置路径
		 * @date 2019-04-17
		 * @param {*} value
		 * @returns 
		 */
		setPath: function (value) {

			this.path = value;
			return this;

		},

		/**
		 * @description 设置资源路径,这个和上一个的区别是上一个可以是一个相对路径，这个是绝对路径
		 * @date 2019-04-17
		 * @param {*} value
		 * @returns 
		 */
		setResourcePath: function (value) {

			this.resourcePath = value;
			return this;

		},

		 /**
		  * @description 设置DRACO文件的加载器
		  * @date 2019-04-17
		  * @param {*} dracoLoader
		  * @returns 
		  */
		 setDRACOLoader: function (dracoLoader) {

			this.dracoLoader = dracoLoader;
			return this;

		},

		/**
		 * @description 加载成功的分析方法
		 * @date 2019-04-17
		 * @param {*} data 加载出来的数据，对于模型来说，一般为arrayBuffer类型的
		 * @param {*} path 加载路径
		 * @param {*} onLoad	加载成功方法
		 * @param {*} onError	加载失败方法
		 * @returns 
		 */
		parse: function (data, path, onLoad, onError) {
			//新建内容变量和拓展变量数组
			var content;
			var extensions = {};
			//判断data类型如果是string类型的直接赋值
			if (typeof data === 'string') {

				content = data;

			} else {
				//如果不是string类型，首先取出前四个判断是不是:"{"
				var magic = THREE.LoaderUtils.decodeText(new Uint8Array(data, 0, 4));
				//如果前四个是gltf，应该是glb格式的二进制文件，获得具体的数据
				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 {
					//如果是正常的gltf就转换类型
					content = THREE.LoaderUtils.decodeText(new Uint8Array(data));

				}

			}
			//转换为json格式
			var json = JSON.parse(content);
			//各个gltf不一样，以下的格式加载就不属于模型的范畴了，加载的东西也是千奇百怪，不具体翻译了，可以对照THREE的gltf对照的看
			if (json.asset === undefined || json.asset.version[0] < 2) {

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

			}

			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_LIGHTS_PUNCTUAL:
							extensions[extensionName] = new GLTFLightsExtension(json);
							break;

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

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

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

						case EXTENSIONS.MSFT_TEXTURE_DDS:
							extensions[EXTENSIONS.MSFT_TEXTURE_DDS] = new GLTFTextureDDSExtension();
							break;

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

						default:

							if (extensionsRequired.indexOf(extensionName) >= 0) {

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

							}

					}

				}

			}

			var parser = new GLTFParser(json, extensions, {

				path: path || this.resourcePath || '',
				crossOrigin: this.crossOrigin,
				manager: this.manager

			});

			parser.parse(function (scene, scenes, cameras, animations, json) {

				var glTF = {
					scene: scene,
					scenes: scenes,
					cameras: cameras,
					animations: animations,
					asset: json.asset,
					parser: parser,
					userData: {}
				};

				addUnknownExtensionsToUserData(extensions, glTF, json);

				onLoad(glTF);

			}, onError);

		}

	};

	/* GLTFREGISTRY */

	/**
	 * @description 创建一个在缓存中的注册函数
	 * @date 2019-04-17
	 * @returns 
	 */
	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_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
		KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
		KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
		MSFT_TEXTURE_DDS: 'MSFT_texture_dds'
	};


	/**
	 * DDS Texture Extension
	 *
	 * Specification:
	 * https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/MSFT_texture_dds
	 *
	 */
	/**
	 * @description dds图片的拓展
	 * @date 2019-04-17
	 */
	function GLTFTextureDDSExtension() {

		if (!THREE.DDSLoader) {

			throw new Error('THREE.GLTFLoader: Attempting to load .dds texture without importing THREE.DDSLoader');

		}

		this.name = EXTENSIONS.MSFT_TEXTURE_DDS;
		this.ddsLoader = new THREE.DDSLoader();

	}

	/**
	 * Lights Extension
	 *
	 * Specification: PENDING
	 */
	/**
	 * @description 灯光的拓展，及获取
	 * @date 2019-04-17
	 * @param {*} json
	 */
	function GLTFLightsExtension(json) {

		this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;

		var extension = (json.extensions && json.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL]) || {};
		this.lightDefs = extension.lights || [];

	}
	/**
	 * @description 加载灯光
	 * @date 2019-04-17
	 * @param {*} lightIndex 灯光的下标
	 */
	GLTFLightsExtension.prototype.loadLight = function (lightIndex) {

		var lightDef = this.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 = lightDef.name || ('light_' + lightIndex);

		return Promise.resolve(lightNode);

	};

	/**
	 * Unlit Materials Extension (pending)
	 *
	 * PR: https://github.com/KhronosGroup/glTF/pull/1163
	 */
	function GLTFMaterialsUnlitExtension(json) {

		this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;

	}

	GLTFMaterialsUnlitExtension.prototype.getMaterialType = function (material) {

		return THREE.MeshBasicMaterial;

	};

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

		var pending = [];

		materialParams.color = new THREE.Color(1.0, 1.0, 1.0);
		materialParams.opacity = 1.0;

		var metallicRoughness = material.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);

	};

	/* BINARY EXTENSION */

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

	/**
	 * @description 加载二进制gltf格式的文件
	 * @date 2019-04-17
	 * @param {*} data 获得到数据
	 */
	function GLTFBinaryExtension(data) {
		//设置名字为gltf二进制文件
		this.name = EXTENSIONS.KHR_BINARY_GLTF;
		//创建内容
		this.content = null;
		//
		this.body = null;
		//获得首视图，获得前12个字符组成的类型视图。
		var headerView = new DataView(data, 0, BINARY_EXTENSION_HEADER_LENGTH);
		//获得头标识，不同的gltf会有不同的处理这里以three的为例
		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. Use LegacyGLTFLoader instead.');

		}
		//这块每个gltf都不太一样，不具体翻译了
		var chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH);
		var chunkIndex = 0;
		//取数据
		while (chunkIndex < chunkView.byteLength) {

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

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

			if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {

				var contentArray = new Uint8Array(data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength);
				this.content = 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 Mesh Compression Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/pull/874
	 */
	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;
		THREE.DRACOLoader.getDecoderModule();

	}

	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) {

			if (!(attributeName in ATTRIBUTES)) continue;

			threeAttributeMap[ATTRIBUTES[attributeName]] = gltfAttributeMap[attributeName];

		}

		for (attributeName in primitive.attributes) {

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

				var accessorDef = json.accessors[primitive.attributes[attributeName]];
				var componentType = WEBGL_COMPONENT_TYPES[accessorDef.componentType];

				attributeTypeMap[ATTRIBUTES[attributeName]] = componentType;
				attributeNormalizedMap[ATTRIBUTES[attributeName]] = 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:
	 */
	function GLTFTextureTransformExtension(json) {

		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
	 */
	/**
	 * @description 拓展材质的shader啥的
	 * @date 2019-04-17
	 * @returns 
	 */
	function GLTFMaterialsPbrSpecularGlossinessExtension() {

		return {

			name: EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS,

			specularGlossinessParams: [
				'color',
				'map',
				'lightMap',
				'lightMapIntensity',
				'aoMap',
				'aoMapIntensity',
				'emissive',
				'emissiveIntensity',
				'emissiveMap',
				'bumpMap',
				'bumpScale',
				'normalMap',
				'displacementMap',
				'displacementScale',
				'displacementBias',
				'specularMap',
				'specular',
				'glossinessMap',
				'glossiness',
				'alphaMap',
				'envMap',
				'envMapIntensity',
				'refractionRatio',
			],

			getMaterialType: function () {

				return THREE.ShaderMaterial;

			},

			extendParams: function (params, material, parser) {

				var pbrSpecularGlossiness = material.extensions[this.name];

				var shader = THREE.ShaderLib['standard'];

				var uniforms = THREE.UniformsUtils.clone(shader.uniforms);

				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;',
					'material.specularRoughness = clamp( 1.0 - glossinessFactor, 0.04, 1.0 );',
					'material.specularColor = specularFactor.rgb;',
				].join('\n');

				var fragmentShader = shader.fragmentShader
					.replace('uniform float roughness;', 'uniform vec3 specular;')
					.replace('uniform float metalness;', 'uniform float glossiness;')
					.replace('#include ', specularMapParsFragmentChunk)
					.replace('#include ', glossinessMapParsFragmentChunk)
					.replace('#include ', specularMapFragmentChunk)
					.replace('#include ', glossinessMapFragmentChunk)
					.replace('#include ', lightPhysicalFragmentChunk);

				delete uniforms.roughness;
				delete uniforms.metalness;
				delete uniforms.roughnessMap;
				delete uniforms.metalnessMap;

				uniforms.specular = {
					value: new THREE.Color().setHex(0x111111)
				};
				uniforms.glossiness = {
					value: 0.5
				};
				uniforms.specularMap = {
					value: null
				};
				uniforms.glossinessMap = {
					value: null
				};

				params.vertexShader = shader.vertexShader;
				params.fragmentShader = fragmentShader;
				params.uniforms = uniforms;
				params.defines = {
					'STANDARD': ''
				};

				params.color = new THREE.Color(1.0, 1.0, 1.0);
				params.opacity = 1.0;

				var pending = [];

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

					var array = pbrSpecularGlossiness.diffuseFactor;

					params.color.fromArray(array);
					params.opacity = array[3];

				}

				if (pbrSpecularGlossiness.diffuseTexture !== undefined) {

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

				}

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

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

					params.specular.fromArray(pbrSpecularGlossiness.specularFactor);

				}

				if (pbrSpecularGlossiness.specularGlossinessTexture !== undefined) {

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

				}

				return Promise.all(pending);

			},

			createMaterial: function (params) {

				// setup material properties based on MeshStandardMaterial for Specular-Glossiness

				var material = new THREE.ShaderMaterial({
					defines: params.defines,
					vertexShader: params.vertexShader,
					fragmentShader: params.fragmentShader,
					uniforms: params.uniforms,
					fog: true,
					lights: true,
					opacity: params.opacity,
					transparent: params.transparent
				});

				material.isGLTFSpecularGlossinessMaterial = true;

				material.color = params.color;

				material.map = params.map === undefined ? null : params.map;

				material.lightMap = null;
				material.lightMapIntensity = 1.0;

				material.aoMap = params.aoMap === undefined ? null : params.aoMap;
				material.aoMapIntensity = 1.0;

				material.emissive = params.emissive;
				material.emissiveIntensity = 1.0;
				material.emissiveMap = params.emissiveMap === undefined ? null : params.emissiveMap;

				material.bumpMap = params.bumpMap === undefined ? null : params.bumpMap;
				material.bumpScale = 1;

				material.normalMap = params.normalMap === undefined ? null : params.normalMap;
				if (params.normalScale) material.normalScale = params.normalScale;

				material.displacementMap = null;
				material.displacementScale = 1;
				material.displacementBias = 0;

				material.specularMap = params.specularMap === undefined ? null : params.specularMap;
				material.specular = params.specular;

				material.glossinessMap = params.glossinessMap === undefined ? null : params.glossinessMap;
				material.glossiness = params.glossiness;

				material.alphaMap = null;

				material.envMap = params.envMap === undefined ? null : params.envMap;
				material.envMapIntensity = 1.0;

				material.refractionRatio = 0.98;

				material.extensions.derivatives = true;

				return material;

			},

			/**
			 * Clones a GLTFSpecularGlossinessMaterial instance. The ShaderMaterial.copy() method can
			 * copy only properties it knows about or inherits, and misses many properties that would
			 * normally be defined by MeshStandardMaterial.
			 *
			 * This method allows GLTFSpecularGlossinessMaterials to be cloned in the process of
			 * loading a glTF model, but cloning later (e.g. by the user) would require these changes
			 * AND also updating `.onBeforeRender` on the parent mesh.
			 *
			 * @param  {THREE.ShaderMaterial} source
			 * @return {THREE.ShaderMaterial}
			 */
			cloneMaterial: function (source) {

				var target = source.clone();

				target.isGLTFSpecularGlossinessMaterial = true;

				var params = this.specularGlossinessParams;

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

					target[params[i]] = source[params[i]];

				}

				return target;

			},

			// Here's based on refreshUniformsCommon() and refreshUniformsStandard() in WebGLRenderer.
			refreshUniforms: function (renderer, scene, camera, geometry, material, group) {

				if (material.isGLTFSpecularGlossinessMaterial !== true) {

					return;

				}

				var uniforms = material.uniforms;
				var defines = material.defines;

				uniforms.opacity.value = material.opacity;

				uniforms.diffuse.value.copy(material.color);
				uniforms.emissive.value.copy(material.emissive).multiplyScalar(material.emissiveIntensity);

				uniforms.map.value = material.map;
				uniforms.specularMap.value = material.specularMap;
				uniforms.alphaMap.value = material.alphaMap;

				uniforms.lightMap.value = material.lightMap;
				uniforms.lightMapIntensity.value = material.lightMapIntensity;

				uniforms.aoMap.value = material.aoMap;
				uniforms.aoMapIntensity.value = material.aoMapIntensity;

				// uv repeat and offset setting priorities
				// 1. color map
				// 2. specular map
				// 3. normal map
				// 4. bump map
				// 5. alpha map
				// 6. emissive map

				var uvScaleMap;

				if (material.map) {

					uvScaleMap = material.map;

				} else if (material.specularMap) {

					uvScaleMap = material.specularMap;

				} else if (material.displacementMap) {

					uvScaleMap = material.displacementMap;

				} else if (material.normalMap) {

					uvScaleMap = material.normalMap;

				} else if (material.bumpMap) {

					uvScaleMap = material.bumpMap;

				} else if (material.glossinessMap) {

					uvScaleMap = material.glossinessMap;

				} else if (material.alphaMap) {

					uvScaleMap = material.alphaMap;

				} else if (material.emissiveMap) {

					uvScaleMap = material.emissiveMap;

				}

				if (uvScaleMap !== undefined) {

					// backwards compatibility
					if (uvScaleMap.isWebGLRenderTarget) {

						uvScaleMap = uvScaleMap.texture;

					}

					if (uvScaleMap.matrixAutoUpdate === true) {

						uvScaleMap.updateMatrix();

					}

					uniforms.uvTransform.value.copy(uvScaleMap.matrix);

				}

				if (material.envMap) {

					uniforms.envMap.value = material.envMap;
					uniforms.envMapIntensity.value = material.envMapIntensity;

					// don't flip CubeTexture envMaps, flip everything else:
					//  WebGLRenderTargetCube will be flipped for backwards compatibility
					//  WebGLRenderTargetCube.texture will be flipped because it's a Texture and NOT a CubeTexture
					// this check must be handled differently, or removed entirely, if WebGLRenderTargetCube uses a CubeTexture in the future
					uniforms.flipEnvMap.value = material.envMap.isCubeTexture ? -1 : 1;

					uniforms.reflectivity.value = material.reflectivity;
					uniforms.refractionRatio.value = material.refractionRatio;

					uniforms.maxMipLevel.value = renderer.properties.get(material.envMap).__maxMipLevel;

				}

				uniforms.specular.value.copy(material.specular);
				uniforms.glossiness.value = material.glossiness;

				uniforms.glossinessMap.value = material.glossinessMap;

				uniforms.emissiveMap.value = material.emissiveMap;
				uniforms.bumpMap.value = material.bumpMap;
				uniforms.normalMap.value = material.normalMap;

				uniforms.displacementMap.value = material.displacementMap;
				uniforms.displacementScale.value = material.displacementScale;
				uniforms.displacementBias.value = material.displacementBias;

				if (uniforms.glossinessMap.value !== null && defines.USE_GLOSSINESSMAP === undefined) {

					defines.USE_GLOSSINESSMAP = '';
					// set USE_ROUGHNESSMAP to enable vUv
					defines.USE_ROUGHNESSMAP = '';

				}

				if (uniforms.glossinessMap.value === null && defines.USE_GLOSSINESSMAP !== undefined) {

					delete defines.USE_GLOSSINESSMAP;
					delete defines.USE_ROUGHNESSMAP;

				}

			}

		};

	}

	/*********************************/
	/********** 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_TYPE = {
		5126: Number,
		//35674: THREE.Matrix2,
		35675: THREE.Matrix3,
		35676: THREE.Matrix4,
		35664: THREE.Vector2,
		35665: THREE.Vector3,
		35666: THREE.Vector4,
		35678: THREE.Texture
	};

	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_SIDES = {
		1028: THREE.BackSide, // Culling front
		1029: THREE.FrontSide // Culling back
		//1032: THREE.NoSide   // Culling front and back, what to do?
	};

	var WEBGL_DEPTH_FUNCS = {
		512: THREE.NeverDepth,
		513: THREE.LessDepth,
		514: THREE.EqualDepth,
		515: THREE.LessEqualDepth,
		516: THREE.GreaterEqualDepth,
		517: THREE.NotEqualDepth,
		518: THREE.GreaterEqualDepth,
		519: THREE.AlwaysDepth
	};

	var WEBGL_BLEND_EQUATIONS = {
		32774: THREE.AddEquation,
		32778: THREE.SubtractEquation,
		32779: THREE.ReverseSubtractEquation
	};

	var WEBGL_BLEND_FUNCS = {
		0: THREE.ZeroFactor,
		1: THREE.OneFactor,
		768: THREE.SrcColorFactor,
		769: THREE.OneMinusSrcColorFactor,
		770: THREE.SrcAlphaFactor,
		771: THREE.OneMinusSrcAlphaFactor,
		772: THREE.DstAlphaFactor,
		773: THREE.OneMinusDstAlphaFactor,
		774: THREE.DstColorFactor,
		775: THREE.OneMinusDstColorFactor,
		776: THREE.SrcAlphaSaturateFactor
		// The followings are not supported by Three.js yet
		//32769: CONSTANT_COLOR,
		//32770: ONE_MINUS_CONSTANT_COLOR,
		//32771: CONSTANT_ALPHA,
		//32772: ONE_MINUS_CONSTANT_COLOR
	};

	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: THREE.InterpolateSmooth, // We use custom interpolation GLTFCubicSplineInterpolation for CUBICSPLINE.
		// KeyframeTrack.optimize() can't handle glTF Cubic Spline output values layout,
		// using THREE.InterpolateSmooth for KeyframeTrack instantiation to prevent optimization.
		// See KeyframeTrack.optimize() for the detail.
		LINEAR: THREE.InterpolateLinear,
		STEP: THREE.InterpolateDiscrete
	};

	var STATES_ENABLES = {
		2884: 'CULL_FACE',
		2929: 'DEPTH_TEST',
		3042: 'BLEND',
		3089: 'SCISSOR_TEST',
		32823: 'POLYGON_OFFSET_FILL',
		32926: 'SAMPLE_ALPHA_TO_COVERAGE'
	};

	var ALPHA_MODES = {
		OPAQUE: 'OPAQUE',
		MASK: 'MASK',
		BLEND: 'BLEND'
	};

	var MIME_TYPE_FORMATS = {
		'image/png': THREE.RGBAFormat,
		'image/jpeg': THREE.RGBFormat
	};

	/* UTILITY FUNCTIONS */

	function resolveURL(url, path) {

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

		// 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;

	}

	var defaultMaterial;

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
	 */
	function createDefaultMaterial() {

		defaultMaterial = defaultMaterial || new THREE.MeshStandardMaterial({
			color: 0xFFFFFF,
			emissive: 0x000000,
			metalness: 1,
			roughness: 1,
			transparent: false,
			depthTest: true,
			side: THREE.FrontSide
		});

		return 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 {THREE.Object3D|THREE.Material|THREE.BufferGeometry} object
	 * @param {GLTF.definition} gltfDef
	 */
	function assignExtrasToUserData(object, gltfDef) {

		if (gltfDef.extras !== undefined) {

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

				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 {THREE.BufferGeometry} geometry
	 * @param {Array} targets
	 * @param {GLTFParser} parser
	 * @return {Promise}
	 */
	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) {

				// TODO: Error-prone use of a callback inside a loop.
				var accessor = target.POSITION !== undefined ?
					parser.getDependency('accessor', target.POSITION)
					.then(function (accessor) {

						// Cloning not to pollute original accessor below
						return cloneBufferAttribute(accessor);

					}) :
					geometry.attributes.position;

				pendingPositionAccessors.push(accessor);

			}

			if (hasMorphNormal) {

				// TODO: Error-prone use of a callback inside a loop.
				var accessor = target.NORMAL !== undefined ?
					parser.getDependency('accessor', target.NORMAL)
					.then(function (accessor) {

						return cloneBufferAttribute(accessor);

					}) :
					geometry.attributes.normal;

				pendingNormalAccessors.push(accessor);

			}

		}

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

			var morphPositions = accessors[0];
			var morphNormals = accessors[1];

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

				var target = targets[i];
				var attributeName = 'morphTarget' + i;

				if (hasMorphPosition) {

					// Three.js morph position is absolute value. The formula is
					//   basePosition
					//     + weight0 * ( morphPosition0 - basePosition )
					//     + weight1 * ( morphPosition1 - basePosition )
					//     ...
					// while the glTF one is relative
					//   basePosition
					//     + weight0 * glTFmorphPosition0
					//     + weight1 * glTFmorphPosition1
					//     ...
					// then we need to convert from relative to absolute here.

					if (target.POSITION !== undefined) {

						var positionAttribute = morphPositions[i];
						positionAttribute.name = attributeName;

						var position = geometry.attributes.position;

						for (var j = 0, jl = positionAttribute.count; j < jl; j++) {

							positionAttribute.setXYZ(
								j,
								positionAttribute.getX(j) + position.getX(j),
								positionAttribute.getY(j) + position.getY(j),
								positionAttribute.getZ(j) + position.getZ(j)
							);

						}

					}

				}

				if (hasMorphNormal) {

					// see target.POSITION's comment

					if (target.NORMAL !== undefined) {

						var normalAttribute = morphNormals[i];
						normalAttribute.name = attributeName;

						var normal = geometry.attributes.normal;

						for (var j = 0, jl = normalAttribute.count; j < jl; j++) {

							normalAttribute.setXYZ(
								j,
								normalAttribute.getX(j) + normal.getX(j),
								normalAttribute.getY(j) + normal.getY(j),
								normalAttribute.getZ(j) + normal.getZ(j)
							);

						}

					}

				}

			}

			if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
			if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;

			return geometry;

		});

	}

	/**
	 * @param {THREE.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 isObjectEqual(a, b) {

		if (Object.keys(a).length !== Object.keys(b).length) return false;

		for (var key in a) {

			if (a[key] !== b[key]) return false;

		}

		return true;

	}

	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 cloneBufferAttribute(attribute) {

		if (attribute.isInterleavedBufferAttribute) {

			var count = attribute.count;
			var itemSize = attribute.itemSize;
			var array = attribute.array.slice(0, count * itemSize);

			for (var i = 0, j = 0; i < count; ++i) {

				array[j++] = attribute.getX(i);
				if (itemSize >= 2) array[j++] = attribute.getY(i);
				if (itemSize >= 3) array[j++] = attribute.getZ(i);
				if (itemSize >= 4) array[j++] = attribute.getW(i);

			}

			return new THREE.BufferAttribute(array, itemSize, attribute.normalized);

		}

		return attribute.clone();

	}

	/* GLTF PARSER */

	function GLTFParser(json, extensions, options) {

		this.json = json || {};
		this.extensions = extensions || {};
		this.options = options || {};

		// loader object cache
		this.cache = new GLTFRegistry();

		// BufferGeometry caching
		this.primitiveCache = {};

		this.textureLoader = new THREE.TextureLoader(this.options.manager);
		this.textureLoader.setCrossOrigin(this.options.crossOrigin);

		this.fileLoader = new THREE.FileLoader(this.options.manager);
		this.fileLoader.setResponseType('arraybuffer');

	}

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

		var json = this.json;

		// Clear the loader cache
		this.cache.removeAll();

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

		// Fire the callback on complete
		this.getMultiDependencies([

			'scene',
			'animation',
			'camera'

		]).then(function (dependencies) {

			var scenes = dependencies.scenes || [];
			var scene = scenes[json.scene || 0];
			var animations = dependencies.animations || [];
			var cameras = dependencies.cameras || [];

			onLoad(scene, scenes, cameras, animations, json);

		}).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 || [];

		var meshReferences = {};
		var meshUses = {};

		// Nothing in the node definition indicates whether it is a Bone or an
		// Object3D. Use the skins' joint references to mark bones.
		for (var skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex++) {

			var joints = skinDefs[skinIndex].joints;

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

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

			}

		}

		// Meshes can (and should) be reused by multiple nodes in a glTF asset. To
		// avoid having more than one THREE.Mesh with the same name, count
		// references and rename instances below.
		//
		// Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
		for (var nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex++) {

			var nodeDef = nodeDefs[nodeIndex];

			if (nodeDef.mesh !== undefined) {

				if (meshReferences[nodeDef.mesh] === undefined) {

					meshReferences[nodeDef.mesh] = meshUses[nodeDef.mesh] = 0;

				}

				meshReferences[nodeDef.mesh]++;

				// Nothing in the mesh definition indicates whether it is
				// a SkinnedMesh or Mesh. Use the node's mesh reference
				// to mark SkinnedMesh if node has skin.
				if (nodeDef.skin !== undefined) {

					meshDefs[nodeDef.mesh].isSkinnedMesh = true;

				}

			}

		}

		this.json.meshReferences = meshReferences;
		this.json.meshUses = meshUses;

	};

	/**
	 * Requests the specified dependency asynchronously, with caching.
	 * @param {string} type
	 * @param {number} index
	 * @return {Promise}
	 */
	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.loadMesh(index);
					break;

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

				case 'bufferView':
					dependency = this.loadBufferView(index);
					break;

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

				case 'material':
					dependency = this.loadMaterial(index);
					break;

				case 'texture':
					dependency = this.loadTexture(index);
					break;

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

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

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

				case 'light':
					dependency = this.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL].loadLight(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>}
	 */
	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;

	};

	/**
	 * Requests all multiple dependencies of the specified types asynchronously, with caching.
	 * @param {Array} types
	 * @return {Promise>>}
	 */
	GLTFParser.prototype.getMultiDependencies = function (types) {

		var results = {};
		var pending = [];

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

			var type = types[i];
			var value = this.getDependencies(type);

			// TODO: Error-prone use of a callback inside a loop.
			value = value.then(function (key, value) {

				results[key] = value;

			}.bind(this, type + (type === 'mesh' ? 'es' : 's')));

			pending.push(value);

		}

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

			return results;

		});

	};

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

				var ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType;
				var ib = parser.cache.get(ibCacheKey);

				if (!ib) {

					// Use the full buffer if it's interleaved.
					array = new TypedArray(bufferView);

					// 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 / 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.setArray(bufferAttribute.array.slice());

				}

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

					var index = sparseIndices[i];

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

				}

			}

			return bufferAttribute;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
	 * @param {number} textureIndex
	 * @return {Promise}
	 */
	GLTFParser.prototype.loadTexture = function (textureIndex) {

		var parser = this;
		var json = this.json;
		var options = this.options;
		var textureLoader = this.textureLoader;

		var URL = window.URL || window.webkitURL;

		var textureDef = json.textures[textureIndex];

		var textureExtensions = textureDef.extensions || {};

		var source;

		if (textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]) {

			source = json.images[textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS].source];

		} else {

			source = json.images[textureDef.source];

		}

		var sourceURI = source.uri;
		var isObjectURL = false;

		if (source.bufferView !== undefined) {

			// Load binary image data from bufferView, if provided.

			sourceURI = parser.getDependency('bufferView', source.bufferView).then(function (bufferView) {

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

			});

		}

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

			// Load Texture resource.

			var loader = THREE.Loader.Handlers.get(sourceURI);

			if (!loader) {

				loader = textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS] ?
					parser.extensions[EXTENSIONS.MSFT_TEXTURE_DDS].ddsLoader :
					textureLoader;

			}

			return new Promise(function (resolve, reject) {

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

			});

		}).then(function (texture) {

			// Clean up resources and configure Texture.

			if (isObjectURL === true) {

				URL.revokeObjectURL(sourceURI);

			}

			texture.flipY = false;

			if (textureDef.name !== undefined) texture.name = textureDef.name;

			// Ignore unknown mime types, like DDS files.
			if (source.mimeType in MIME_TYPE_FORMATS) {

				texture.format = MIME_TYPE_FORMATS[source.mimeType];

			}

			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;

			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) {

			switch (mapName) {

				case 'aoMap':
				case 'emissiveMap':
				case 'metalnessMap':
				case 'normalMap':
				case 'roughnessMap':
					texture.format = THREE.RGBFormat;
					break;

			}

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

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

				if (transform) {

					texture = parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM].extendTexture(texture, transform);

				}

			}

			materialParams[mapName] = texture;

		});

	};

	/**
	 * Assigns final material to a Mesh, Line, or Points instance. The instance
	 * already has a material (generated from the glTF material options alone)
	 * but reuse of the same glTF material may require multiple threejs materials
	 * to accomodate different primitive types, defines, etc. New materials will
	 * be created if necessary, and reused from a cache.
	 * @param  {THREE.Object3D} mesh Mesh, Line, or Points instance.
	 */
	GLTFParser.prototype.assignFinalMaterial = function (mesh) {

		var geometry = mesh.geometry;
		var material = mesh.material;
		var extensions = this.extensions;

		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.lights = false; // PointsMaterial doesn't support lights yet

				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);
				lineMaterial.lights = false; // LineBasicMaterial doesn't support lights yet

				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.isGLTFSpecularGlossinessMaterial ?
					extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS].cloneMaterial(material) :
					material.clone();

				if (useSkinning) cachedMaterial.skinning = true;
				if (useVertexTangents) cachedMaterial.vertexTangents = true;
				if (useVertexColors) cachedMaterial.vertexColors = THREE.VertexColors;
				if (useFlatShading) cachedMaterial.flatShading = true;
				if (useMorphTargets) cachedMaterial.morphTargets = true;
				if (useMorphNormals) cachedMaterial.morphNormals = true;

				this.cache.add(cacheKey, cachedMaterial);

			}

			material = cachedMaterial;

		}

		// workarounds for mesh and geometry

		if (material.aoMap && geometry.attributes.uv2 === undefined && geometry.attributes.uv !== undefined) {

			console.log('THREE.GLTFLoader: Duplicating UVs to support aoMap.');
			geometry.addAttribute('uv2', new THREE.BufferAttribute(geometry.attributes.uv.array, 2));

		}

		if (material.isGLTFSpecularGlossinessMaterial) {

			// for GLTFSpecularGlossinessMaterial(ShaderMaterial) uniforms runtime update
			mesh.onBeforeRender = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS].refreshUniforms;

		}

		mesh.material = material;

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
	 * @param {number} materialIndex
	 * @return {Promise}
	 */
	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(materialDef);
			pending.push(sgExtension.extendParams(materialParams, materialDef, parser));

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

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

		} else {

			// Specification:
			// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material

			materialType = THREE.MeshStandardMaterial;

			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));

			}

		}

		if (materialDef.doubleSided === true) {

			materialParams.side = THREE.DoubleSide;

		}

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

		if (alphaMode === ALPHA_MODES.BLEND) {

			materialParams.transparent = true;

		} else {

			materialParams.transparent = false;

			if (alphaMode === ALPHA_MODES.MASK) {

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

			}

		}

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

			pending.push(parser.assignTexture(materialParams, 'normalMap', materialDef.normalTexture));

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

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

				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 === THREE.ShaderMaterial) {

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

			} else {

				material = new materialType(materialParams);

			}

			if (materialDef.name !== undefined) 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;
			if (material.specularMap) material.specularMap.encoding = THREE.sRGBEncoding;

			assignExtrasToUserData(material, materialDef);

			if (materialDef.extensions) addUnknownExtensionsToUserData(extensions, material, materialDef);

			return material;

		});

	};

	/**
	 * @param {THREE.BufferGeometry} geometry
	 * @param {GLTF.Primitive} primitiveDef
	 * @param {GLTFParser} parser
	 * @return {Promise}
	 */
	function addPrimitiveAttributes(geometry, primitiveDef, parser) {

		var attributes = primitiveDef.attributes;

		var pending = [];

		function assignAttributeAccessor(accessorIndex, attributeName) {

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

					geometry.addAttribute(attributeName, accessor);

				});

		}

		for (var gltfAttributeName in attributes) {

			var threeAttributeName = ATTRIBUTES[gltfAttributeName];

			if (!threeAttributeName) continue;

			// 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);

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

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

		});

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
	 *
	 * Creates BufferGeometries from primitives.
	 *
	 * @param {Array} primitives
	 * @return {Promise>}
	 */
	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}
	 */
	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.getDependency('material', primitives[i].material);

			pending.push(material);

		}

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

			return parser.loadGeometries(primitives).then(function (geometries) {

				var meshes = [];

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

					var geometry = geometries[i];
					var primitive = primitives[i];

					// 1. create Mesh

					var mesh;

					var material = originalMaterials[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.normalizeSkinWeights(); // #15319

						if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP) {

							mesh.drawMode = THREE.TriangleStripDrawMode;

						} else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {

							mesh.drawMode = 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 = meshDef.name || ('mesh_' + meshIndex);

					if (geometries.length > 1) mesh.name += '_' + i;

					assignExtrasToUserData(mesh, meshDef);

					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}
	 */
	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.Math.radToDeg(params.yfov), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6);

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

			camera = new THREE.OrthographicCamera(params.xmag / -2, params.xmag / 2, params.ymag / 2, params.ymag / -2, params.znear, params.zfar);

		}

		if (cameraDef.name !== undefined) camera.name = 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