text: /**
   * @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
   */
  
  import {
  	AnimationClip,
  	Bone,
  	Box3,
  	BufferAttribute,
  	BufferGeometry,
  	ClampToEdgeWrapping,
  	Color,
  	DirectionalLight,
  	DoubleSide,
  	FileLoader,
  	FrontSide,
  	Group,
  	InterleavedBuffer,
  	InterleavedBufferAttribute,
  	Interpolant,
  	InterpolateDiscrete,
  	InterpolateLinear,
  	Line,
  	LineBasicMaterial,
  	LineLoop,
  	LineSegments,
  	LinearFilter,
  	LinearMipmapLinearFilter,
  	LinearMipmapNearestFilter,
  	Loader,
  	LoaderUtils,
  	Material,
  	MathUtils,
  	Matrix4,
  	Mesh,
  	MeshBasicMaterial,
  	MeshPhysicalMaterial,
  	MeshStandardMaterial,
  	MirroredRepeatWrapping,
  	NearestFilter,
  	NearestMipmapLinearFilter,
  	NearestMipmapNearestFilter,
  	NumberKeyframeTrack,
  	Object3D,
  	OrthographicCamera,
  	PerspectiveCamera,
  	PointLight,
  	Points,
  	PointsMaterial,
  	PropertyBinding,
  	QuaternionKeyframeTrack,
  	RGBAFormat,
  	RGBFormat,
  	RepeatWrapping,
  	Skeleton,
  	SkinnedMesh,
  	Sphere,
  	SpotLight,
  	TangentSpaceNormalMap,
  	TextureLoader,
  	TriangleFanDrawMode,
  	TriangleStripDrawMode,
  	Vector2,
  	Vector3,
  	VectorKeyframeTrack,
  	sRGBEncoding
  } from "../../build/three.module.js";
  
  var GLTFLoader = ( function () {
  
  	function GLTFLoader( manager ) {
  
  		Loader.call( this, manager );
  
  		this.dracoLoader = null;
  		this.ddsLoader = null;
  
  	}
  
  	GLTFLoader.prototype = Object.assign( Object.create( 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 = 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.
  			scope.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 FileLoader( scope.manager );
  
  			loader.setPath( this.path );
  			loader.setResponseType( 'arraybuffer' );
  
  			if ( scope.crossOrigin === 'use-credentials' ) {
  
  				loader.setWithCredentials( true );
  
  			}
  
  			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 ( ddsLoader ) {
  
  			this.ddsLoader = ddsLoader;
  			return this;
  
  		},
  
  		parse: function ( data, path, onLoad, onError ) {
  
  			var content;
  			var extensions = {};
  
  			if ( typeof data === 'string' ) {
  
  				content = data;
  
  			} else {
  
  				var magic = LoaderUtils.decodeText( new Uint8Array( data, 0, 4 ) );
  
  				if ( magic === BINARY_EXTENSION_HEADER_MAGIC ) {
  
  					try {
  
  						extensions[ EXTENSIONS.KHR_BINARY_GLTF ] = new GLTFBinaryExtension( data );
  
  					} catch ( error ) {
  
  						if ( onError ) onError( error );
  						return;
  
  					}
  
  					content = extensions[ EXTENSIONS.KHR_BINARY_GLTF ].content;
  
  				} else {
  
  					content = LoaderUtils.decodeText( new Uint8Array( data ) );
  
  				}
  
  			}
  
  			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;
  
  			}
  
  			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_CLEARCOAT:
  							extensions[ extensionName ] = new GLTFMaterialsClearcoatExtension();
  							break;
  
  						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.MSFT_TEXTURE_DDS:
  							extensions[ extensionName ] = new GLTFTextureDDSExtension( this.ddsLoader );
  							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 ) {
  
  								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( 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_UNLIT: 'KHR_materials_unlit',
  		KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
  		KHR_MESH_QUANTIZATION: 'KHR_mesh_quantization',
  		MSFT_TEXTURE_DDS: 'MSFT_texture_dds'
  	};
  
  	/**
  	 * DDS Texture Extension
  	 *
  	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/MSFT_texture_dds
  	 *
  	 */
  	function GLTFTextureDDSExtension( ddsLoader ) {
  
  		if ( ! ddsLoader ) {
  
  			throw new Error( 'THREE.GLTFLoader: Attempting to load .dds texture without importing DDSLoader' );
  
  		}
  
  		this.name = EXTENSIONS.MSFT_TEXTURE_DDS;
  		this.ddsLoader = ddsLoader;
  
  	}
  
  	/**
  	 * Punctual Lights Extension
  	 *
  	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
  	 */
  	function GLTFLightsExtension( json ) {
  
  		this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;
  
  		var extension = ( json.extensions && json.extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ] ) || {};
  		this.lightDefs = extension.lights || [];
  
  	}
  
  	GLTFLightsExtension.prototype.loadLight = function ( lightIndex ) {
  
  		var lightDef = this.lightDefs[ lightIndex ];
  		var lightNode;
  
  		var color = new 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 DirectionalLight( color );
  				lightNode.target.position.set( 0, 0, - 1 );
  				lightNode.add( lightNode.target );
  				break;
  
  			case 'point':
  				lightNode = new PointLight( color );
  				lightNode.distance = range;
  				break;
  
  			case 'spot':
  				lightNode = new SpotLight( color );
  				lightNode.distance = range;
  				// Handle spotlight properties.
  				lightDef.spot = lightDef.spot || {};
  				lightDef.spot.innerConeAngle = lightDef.spot.innerConeAngle !== undefined ? lightDef.spot.innerConeAngle : 0;
  				lightDef.spot.outerConeAngle = lightDef.spot.outerConeAngle !== undefined ? lightDef.spot.outerConeAngle : Math.PI / 4.0;
  				lightNode.angle = lightDef.spot.outerConeAngle;
  				lightNode.penumbra = 1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
  				lightNode.target.position.set( 0, 0, - 1 );
  				lightNode.add( lightNode.target );
  				break;
  
  			default:
  				throw new Error( 'THREE.GLTFLoader: Unexpected light type, "' + lightDef.type + '".' );
  
  		}
  
  		// Some lights (e.g. spot) default to a position other than the origin. Reset the position
  		// here, because node-level parsing will only override position if explicitly specified.
  		lightNode.position.set( 0, 0, 0 );
  
  		lightNode.decay = 2;
  
  		if ( lightDef.intensity !== undefined ) lightNode.intensity = lightDef.intensity;
  
  		lightNode.name = lightDef.name || ( 'light_' + lightIndex );
  
  		return Promise.resolve( lightNode );
  
  	};
  
  	/**
  	 * 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 MeshBasicMaterial;
  
  	};
  
  	GLTFMaterialsUnlitExtension.prototype.extendParams = function ( materialParams, materialDef, parser ) {
  
  		var pending = [];
  
  		materialParams.color = new 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() {
  
  		this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;
  
  	}
  
  	GLTFMaterialsClearcoatExtension.prototype.getMaterialType = function () {
  
  		return MeshPhysicalMaterial;
  
  	};
  
  	GLTFMaterialsClearcoatExtension.prototype.extendParams = function ( materialParams, materialDef, parser ) {
  
  		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;
  
  				materialParams.clearcoatNormalScale = new Vector2( scale, scale );
  
  			}
  
  		}
  
  		return Promise.all( pending );
  
  	};
  
  	/* 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: 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 chunkView = new DataView( data, BINARY_EXTENSION_HEADER_LENGTH );
  		var chunkIndex = 0;
  
  		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 = 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/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 ) {
  
  		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;',
  			'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.rgb;',
  		].join( '\n' );
  
  		var uniforms = {
  			specular: { value: new Color().setHex( 0xffffff ) },
  			glossiness: { value: 1 },
  			specularMap: { value: null },
  			glossinessMap: { value: null }
  		};
  
  		this._extraUniforms = uniforms;
  
  		// please see #14031 or #13198 for an alternate approach
  		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;' );
  			shader.fragmentShader = shader.fragmentShader.replace( 'uniform float metalness;', 'uniform float glossiness;' );
  			shader.fragmentShader = shader.fragmentShader.replace( '#include <roughnessmap_pars_fragment>', specularMapParsFragmentChunk );
  			shader.fragmentShader = shader.fragmentShader.replace( '#include <metalnessmap_pars_fragment>', glossinessMapParsFragmentChunk );
  			shader.fragmentShader = shader.fragmentShader.replace( '#include <roughnessmap_fragment>', specularMapFragmentChunk );
  			shader.fragmentShader = shader.fragmentShader.replace( '#include <metalnessmap_fragment>', glossinessMapFragmentChunk );
  			shader.fragmentShader = shader.fragmentShader.replace( '#include <lights_physical_fragment>', lightPhysicalFragmentChunk );
  
  		};
  
  		/*eslint-disable*/
  		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; }
  				},
  				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;
  						//how about something like this - @pailhead
  						if ( v ) {
  
  							this.defines.USE_GLOSSINESSMAP = '';
  							// set USE_ROUGHNESSMAP to enable vUv
  							this.defines.USE_ROUGHNESSMAP = '';
  
  						} else {
  
  							delete this.defines.USE_ROUGHNESSMAP;
  							delete this.defines.USE_GLOSSINESSMAP;
  
  						}
  
  					}
  				}
  			}
  		);
  
  		/*eslint-enable*/
  		delete this.metalness;
  		delete this.roughness;
  		delete this.metalnessMap;
  		delete this.roughnessMap;
  
  		this.setValues( params );
  
  	}
  
  	GLTFMeshStandardSGMaterial.prototype = Object.create( MeshStandardMaterial.prototype );
  	GLTFMeshStandardSGMaterial.prototype.constructor = GLTFMeshStandardSGMaterial;
  
  	GLTFMeshStandardSGMaterial.prototype.copy = function ( source ) {
  
  		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 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 Color( 0.0, 0.0, 0.0 );
  				materialParams.glossiness = pbrSpecularGlossiness.glossinessFactor !== undefined ? pbrSpecularGlossiness.glossinessFactor : 1.0;
  				materialParams.specular = new Color( 1.0, 1.0, 1.0 );
  
  				if ( Array.isArray( pbrSpecularGlossiness.specularFactor ) ) {
  
  					materialParams.specular.fromArray( pbrSpecularGlossiness.specularFactor );
  
  				}
  
  				if ( pbrSpecularGlossiness.specularGlossinessTexture !== undefined ) {
  
  					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 = 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;
  
  			},
  
  		};
  
  	}
  
  	/**
  	 * 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 ) {
  
  		Interpolant.call( this, parameterPositions, sampleValues, sampleSize, resultBuffer );
  
  	}
  
  	GLTFCubicSplineInterpolant.prototype = Object.create( 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: NearestFilter,
  		9729: LinearFilter,
  		9984: NearestMipmapNearestFilter,
  		9985: LinearMipmapNearestFilter,
  		9986: NearestMipmapLinearFilter,
  		9987: LinearMipmapLinearFilter
  	};
  
  	var WEBGL_WRAPPINGS = {
  		33071: ClampToEdgeWrapping,
  		33648: MirroredRepeatWrapping,
  		10497: 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: InterpolateLinear,
  		STEP: InterpolateDiscrete
  	};
  
  	var ALPHA_MODES = {
  		OPAQUE: 'OPAQUE',
  		MASK: 'MASK',
  		BLEND: 'BLEND'
  	};
  
  	var MIME_TYPE_FORMATS = {
  		'image/png': RGBAFormat,
  		'image/jpeg': RGBFormat
  	};
  
  	/* 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 MeshStandardMaterial( {
  				color: 0xFFFFFF,
  				emissive: 0x000000,
  				metalness: 1,
  				roughness: 1,
  				transparent: false,
  				depthTest: true,
  				side: FrontSide
  			} );
  
  		}
  
  		return cache[ 'DefaultMaterial' ];
  
  	}
  
  	function addUnknownExtensionsToUserData( knownExtensions, object, objectDef ) {
  
  		// Add unknown glTF extensions to an object's userData.
  
  		for ( 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;
  
  	}
  
  	/* 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 TextureLoader( this.options.manager );
  		this.textureLoader.setCrossOrigin( this.options.crossOrigin );
  
  		this.fileLoader = new FileLoader( this.options.manager );
  		this.fileLoader.setResponseType( 'arraybuffer' );
  
  		if ( this.options.crossOrigin === 'use-credentials' ) {
  
  			this.fileLoader.setWithCredentials( true );
  
  		}
  
  	}
  
  	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.markDefs();
  
  		Promise.all( [
  
  			this.getDependencies( 'scene' ),
  			this.getDependencies( 'animation' ),
  			this.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 );
  
  			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 || [];
  
  		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 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<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.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<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 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 InterleavedBuffer( array, byteStride / elementBytes );
  
  					parser.cache.add( ibCacheKey, ib );
  
  				}
  
  				bufferAttribute = new InterleavedBufferAttribute( ib, itemSize, ( byteOffset % byteStride ) / elementBytes, normalized );
  
  			} else {
  
  				if ( bufferView === null ) {
  
  					array = new TypedArray( accessorDef.count * itemSize );
  
  				} else {
  
  					array = new TypedArray( bufferView, byteOffset, accessorDef.count * itemSize );
  
  				}
  
  				bufferAttribute = new BufferAttribute( array, itemSize, normalized );
  
  			}
  
  			// https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
  			if ( accessorDef.sparse !== undefined ) {
  
  				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 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 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 parser = this;
  		var json = this.json;
  		var options = this.options;
  		var textureLoader = this.textureLoader;
  
  		var URL = self.URL || self.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 = options.manager.getHandler( 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 ) 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 ] || LinearFilter;
  			texture.minFilter = WEBGL_FILTERS[ sampler.minFilter ] || LinearMipmapLinearFilter;
  			texture.wrapS = WEBGL_WRAPPINGS[ sampler.wrapS ] || RepeatWrapping;
  			texture.wrapT = WEBGL_WRAPPINGS[ sampler.wrapT ] || 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 ) {
  
  			if ( ! texture.isCompressedTexture ) {
  
  				switch ( mapName ) {
  
  					case 'aoMap':
  					case 'emissiveMap':
  					case 'metalnessMap':
  					case 'normalMap':
  					case 'roughnessMap':
  						texture.format = RGBFormat;
  						break;
  
  				}
  
  			}
  
  			// 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 ) {
  
  					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  {Object3D} mesh Mesh, Line, or 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 PointsMaterial();
  				Material.prototype.copy.call( pointsMaterial, material );
  				pointsMaterial.color.copy( material.color );
  				pointsMaterial.map = material.map;
  				pointsMaterial.sizeAttenuation = false; // glTF spec says points should be 1px
  
  				this.cache.add( cacheKey, pointsMaterial );
  
  			}
  
  			material = pointsMaterial;
  
  		} else if ( mesh.isLine ) {
  
  			var cacheKey = 'LineBasicMaterial:' + material.uuid;
  
  			var lineMaterial = this.cache.get( cacheKey );
  
  			if ( ! lineMaterial ) {
  
  				lineMaterial = new LineBasicMaterial();
  				Material.prototype.copy.call( lineMaterial, material );
  				lineMaterial.color.copy( material.color );
  
  				this.cache.add( cacheKey, lineMaterial );
  
  			}
  
  			material = lineMaterial;
  
  		}
  
  		// Clone the material if it will be modified
  		if ( 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 ( useVertexTangents ) cachedMaterial.vertexTangents = true;
  				if ( useVertexColors ) cachedMaterial.vertexColors = true;
  				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 ) {
  
  			geometry.setAttribute( 'uv2', new BufferAttribute( geometry.attributes.uv.array, 2 ) );
  
  		}
  
  		// https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
  		if ( material.normalScale && ! useVertexTangents ) {
  
  			material.normalScale.y = - material.normalScale.y;
  
  		}
  
  		if ( material.clearcoatNormalScale && ! useVertexTangents ) {
  
  			material.clearcoatNormalScale.y = - material.clearcoatNormalScale.y;
  
  		}
  
  		mesh.material = material;
  
  	};
  
  	/**
  	 * 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
  
  			materialType = MeshStandardMaterial;
  
  			var metallicRoughness = materialDef.pbrMetallicRoughness || {};
  
  			materialParams.color = new 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 = 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 !== MeshBasicMaterial ) {
  
  			pending.push( parser.assignTexture( materialParams, 'normalMap', materialDef.normalTexture ) );
  
  			materialParams.normalScale = new Vector2( 1, 1 );
  
  			if ( materialDef.normalTexture.scale !== undefined ) {
  
  				materialParams.normalScale.set( materialDef.normalTexture.scale, materialDef.normalTexture.scale );
  
  			}
  
  		}
  
  		if ( materialDef.occlusionTexture !== undefined && materialType !== MeshBasicMaterial ) {
  
  			pending.push( parser.assignTexture( materialParams, 'aoMap', materialDef.occlusionTexture ) );
  
  			if ( materialDef.occlusionTexture.strength !== undefined ) {
  
  				materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;
  
  			}
  
  		}
  
  		if ( materialDef.emissiveFactor !== undefined && materialType !== MeshBasicMaterial ) {
  
  			materialParams.emissive = new Color().fromArray( materialDef.emissiveFactor );
  
  		}
  
  		if ( materialDef.emissiveTexture !== undefined && materialType !== MeshBasicMaterial ) {
  
  			pending.push( parser.assignTexture( materialParams, 'emissiveMap', materialDef.emissiveTexture ) );
  
  		}
  
  		if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_CLEARCOAT ] ) {
  
  			var clearcoatExtension = extensions[ EXTENSIONS.KHR_MATERIALS_CLEARCOAT ];
  			materialType = clearcoatExtension.getMaterialType();
  			pending.push( clearcoatExtension.extendParams( materialParams, { extensions: materialExtensions }, parser ) );
  
  		}
  
  		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 = sRGBEncoding;
  			if ( material.emissiveMap ) material.emissiveMap.encoding = sRGBEncoding;
  
  			assignExtrasToUserData( material, materialDef );
  
  			if ( materialDef.extensions ) addUnknownExtensionsToUserData( extensions, material, materialDef );
  
  			return material;
  
  		} );
  
  	};
  
  	/**
  	 * @param {BufferGeometry} geometry
  	 * @param {GLTF.Primitive} primitiveDef
  	 * @param {GLTFParser} parser
  	 */
  	function computeBounds( geometry, primitiveDef, parser ) {
  
  		var attributes = primitiveDef.attributes;
  
  		var box = new 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 Vector3( min[ 0 ], min[ 1 ], min[ 2 ] ),
  					new Vector3( max[ 0 ], max[ 1 ], max[ 2 ] ) );
  
  			} 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 Vector3();
  			var vector = new 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 ] ) ) );
  
  						// 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 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 === 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 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 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 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 SkinnedMesh( geometry, material )
  						: new Mesh( geometry, material );
  
  					if ( mesh.isSkinnedMesh === true && ! mesh.geometry.attributes.skinWeight.normalized ) {
  
  						// we normalize floating point skin weight array to fix malformed assets (see #15319)
  						// it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
  						mesh.normalizeSkinWeights();
  
  					}
  
  					if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ) {
  
  						mesh.geometry = toTrianglesDrawMode( mesh.geometry, TriangleStripDrawMode );
  
  					} else if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ) {
  
  						mesh.geometry = toTrianglesDrawMode( mesh.geometry, TriangleFanDrawMode );
  
  					}
  
  				} else if ( primitive.mode === WEBGL_CONSTANTS.LINES ) {
  
  					mesh = new LineSegments( geometry, material );
  
  				} else if ( primitive.mode === WEBGL_CONSTANTS.LINE_STRIP ) {
  
  					mesh = new Line( geometry, material );
  
  				} else if ( primitive.mode === WEBGL_CONSTANTS.LINE_LOOP ) {
  
  					mesh = new LineLoop( geometry, material );
  
  				} else if ( primitive.mode === WEBGL_CONSTANTS.POINTS ) {
  
  					mesh = new Points( geometry, material );
  
  				} else {
  
  					throw new Error( 'THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode );
  
  				}
  
  				if ( Object.keys( mesh.geometry.morphAttributes ).length > 0 ) {
  
  					updateMorphTargets( mesh, meshDef );
  
  				}
  
  				mesh.name = 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 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 PerspectiveCamera( MathUtils.radToDeg( params.yfov ), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6 );
  
  		} else if ( cameraDef.type === 'orthographic' ) {
  
  			camera = new OrthographicCamera( params.xmag / - 2, params.xmag / 2, params.ymag / 2, params.ymag / - 2, params.znear, params.zfar );
  
  		}
  
  		if ( cameraDef.name ) 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<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 = NumberKeyframeTrack;
  						break;
  
  					case PATH_PROPERTIES.rotation:
  
  						TypedKeyframeTrack = QuaternionKeyframeTrack;
  						break;
  
  					case PATH_PROPERTIES.position:
  					case PATH_PROPERTIES.scale:
  					default:
  
  						TypedKeyframeTrack = VectorKeyframeTrack;
  						break;
  
  				}
  
  				var targetName = node.name ? node.name : node.uuid;
  
  				var interpolation = sampler.interpolation !== undefined ? INTERPOLATION[ sampler.interpolation ] : InterpolateLinear;
  
  				var targetNames = [];
  
  				if ( PATH_PROPERTIES[ target.path ] === PATH_PROPERTIES.weights ) {
  
  					// Node may be a Group (glTF mesh with several primitives) or a 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;
  
  					if ( outputArray.constructor === Int8Array ) {
  
  						scale = 1 / 127;
  
  					} else if ( outputArray.constructor === Uint8Array ) {
  
  						scale = 1 / 255;
  
  					} else if ( outputArray.constructor == Int16Array ) {
  
  						scale = 1 / 32767;
  
  					} else if ( outputArray.constructor === Uint16Array ) {
  
  						scale = 1 / 65535;
  
  					} else {
  
  						throw new Error( 'THREE.GLTFLoader: Unsupported output accessor component type.' );
  
  					}
  
  					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 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 meshReferences = json.meshReferences;
  		var meshUses = json.meshUses;
  
  		var nodeDef = json.nodes[ nodeIndex ];
  
  		return ( function () {
  
  			var pending = [];
  
  			if ( nodeDef.mesh !== undefined ) {
  
  				pending.push( parser.getDependency( 'mesh', nodeDef.mesh ).then( function ( mesh ) {
  
  					var node;
  
  					if ( meshReferences[ nodeDef.mesh ] > 1 ) {
  
  						var instanceNum = meshUses[ nodeDef.mesh ] ++;
  
  						node = mesh.clone();
  						node.name += '_instance_' + instanceNum;
  
  					} else {
  
  						node = 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 ) );
  
  			}
  
  			if ( nodeDef.extensions
  				&& nodeDef.extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ]
  				&& nodeDef.extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ].light !== undefined ) {
  
  				pending.push( parser.getDependency( 'light', nodeDef.extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ].light ) );
  
  			}
  
  			return Promise.all( pending );
  
  		}() ).then( function ( objects ) {
  
  			var node;
  
  			// .isBone isn't in glTF spec. See .markDefs
  			if ( nodeDef.isBone === true ) {
  
  				node = new Bone();
  
  			} else if ( objects.length > 1 ) {
  
  				node = new Group();
  
  			} else if ( objects.length === 1 ) {
  
  				node = objects[ 0 ];
  
  			} else {
  
  				node = new Object3D();
  
  			}
  
  			if ( node !== objects[ 0 ] ) {
  
  				for ( var i = 0, il = objects.length; i < il; i ++ ) {
  
  					node.add( objects[ i ] );
  
  				}
  
  			}
  
  			if ( nodeDef.name ) {
  
  				node.userData.name = nodeDef.name;
  				node.name = PropertyBinding.sanitizeNodeName( nodeDef.name );
  
  			}
  
  			assignExtrasToUserData( node, nodeDef );
  
  			if ( nodeDef.extensions ) addUnknownExtensionsToUserData( extensions, node, nodeDef );
  
  			if ( nodeDef.matrix !== undefined ) {
  
  				var matrix = new Matrix4();
  				matrix.fromArray( nodeDef.matrix );
  				node.applyMatrix4( matrix );
  
  			} else {
  
  				if ( nodeDef.translation !== undefined ) {
  
  					node.position.fromArray( nodeDef.translation );
  
  				}
  
  				if ( nodeDef.rotation !== undefined ) {
  
  					node.quaternion.fromArray( nodeDef.rotation );
  
  				}
  
  				if ( nodeDef.scale !== undefined ) {
  
  					node.scale.fromArray( nodeDef.scale );
  
  				}
  
  			}
  
  			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 Matrix4();
  
  								if ( skinEntry.inverseBindMatrices !== undefined ) {
  
  									mat.fromArray( skinEntry.inverseBindMatrices.array, j * 16 );
  
  								}
  
  								boneInverses.push( mat );
  
  							} else {
  
  								console.warn( 'THREE.GLTFLoader: Joint "%s" could not be found.', skinEntry.joints[ j ] );
  
  							}
  
  						}
  
  						mesh.bind( new Skeleton( bones, boneInverses ), mesh.matrixWorld );
  
  					} );
  
  					return node;
  
  				} );
  
  			} ).then( function ( node ) {
  
  				// build node hierachy
  
  				parentObject.add( node );
  
  				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;
  
  			// Loader returns Group, not Scene.
  			// See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172
  			var scene = new Group();
  			if ( sceneDef.name ) scene.name = 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;
  
  } )();
  
  export { GLTFLoader };
  