text: //------------------------------------------------------------------------------
  // Constants
  //------------------------------------------------------------------------------
  var WEBGL_CONSTANTS = {
  	POINTS: 0x0000,
  	LINES: 0x0001,
  	LINE_LOOP: 0x0002,
  	LINE_STRIP: 0x0003,
  	TRIANGLES: 0x0004,
  	TRIANGLE_STRIP: 0x0005,
  	TRIANGLE_FAN: 0x0006,
  
  	UNSIGNED_BYTE: 0x1401,
  	UNSIGNED_SHORT: 0x1403,
  	FLOAT: 0x1406,
  	UNSIGNED_INT: 0x1405,
  	ARRAY_BUFFER: 0x8892,
  	ELEMENT_ARRAY_BUFFER: 0x8893,
  
  	NEAREST: 0x2600,
  	LINEAR: 0x2601,
  	NEAREST_MIPMAP_NEAREST: 0x2700,
  	LINEAR_MIPMAP_NEAREST: 0x2701,
  	NEAREST_MIPMAP_LINEAR: 0x2702,
  	LINEAR_MIPMAP_LINEAR: 0x2703,
  
  	CLAMP_TO_EDGE: 33071,
  	MIRRORED_REPEAT: 33648,
  	REPEAT: 10497
  };
  
  var identityArray = [ 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 ];
  
  var THREE_TO_WEBGL = {};
  
  THREE_TO_WEBGL[ THREE.NearestFilter ] = WEBGL_CONSTANTS.NEAREST;
  THREE_TO_WEBGL[ THREE.NearestMipmapNearestFilter ] = WEBGL_CONSTANTS.NEAREST_MIPMAP_NEAREST;
  THREE_TO_WEBGL[ THREE.NearestMipmapLinearFilter ] = WEBGL_CONSTANTS.NEAREST_MIPMAP_LINEAR;
  THREE_TO_WEBGL[ THREE.LinearFilter ] = WEBGL_CONSTANTS.LINEAR;
  THREE_TO_WEBGL[ THREE.LinearMipmapNearestFilter ] = WEBGL_CONSTANTS.LINEAR_MIPMAP_NEAREST;
  THREE_TO_WEBGL[ THREE.LinearMipmapLinearFilter ] = WEBGL_CONSTANTS.LINEAR_MIPMAP_LINEAR;
  
  THREE_TO_WEBGL[ THREE.ClampToEdgeWrapping ] = WEBGL_CONSTANTS.CLAMP_TO_EDGE;
  THREE_TO_WEBGL[ THREE.RepeatWrapping ] = WEBGL_CONSTANTS.REPEAT;
  THREE_TO_WEBGL[ THREE.MirroredRepeatWrapping ] = WEBGL_CONSTANTS.MIRRORED_REPEAT;
  
  var PATH_PROPERTIES = {
  	scale: 'scale',
  	position: 'translation',
  	quaternion: 'rotation',
  	morphTargetInfluences: 'weights'
  };
  
  //------------------------------------------------------------------------------
  // GLTF Exporter
  //------------------------------------------------------------------------------
  THREE.GLTFExporter = function () {};
  
  THREE.GLTFExporter.prototype = {
  
  	constructor: THREE.GLTFExporter,
  
  	/**
  	 * Parse scenes and generate GLTF output
  	 * @param  {THREE.Scene or [THREE.Scenes]} input   THREE.Scene or Array of THREE.Scenes
  	 * @param  {Function} onDone  Callback on completed
  	 * @param  {Object} options options
  	 */
  	parse: function ( input, onDone, options ) {
  
  		var DEFAULT_OPTIONS = {
  			binary: false,
  			trs: false,
  			onlyVisible: true,
  			truncateDrawRange: true,
  			embedImages: true,
  			maxTextureSize: Infinity,
  			animations: [],
  			forcePowerOfTwoTextures: false,
  			includeCustomExtensions: false
  		};
  
  		options = Object.assign( {}, DEFAULT_OPTIONS, options );
  
  		if ( options.animations.length > 0 ) {
  
  			// Only TRS properties, and not matrices, may be targeted by animation.
  			options.trs = true;
  
  		}
  
  		var outputJSON = {
  
  			asset: {
  
  				version: "2.0",
  				generator: "THREE.GLTFExporter"
  
  			}
  
  		};
  
  		var byteOffset = 0;
  		var buffers = [];
  		var pending = [];
  		var nodeMap = new Map();
  		var skins = [];
  		var extensionsUsed = {};
  		var cachedData = {
  
  			meshes: new Map(),
  			attributes: new Map(),
  			attributesNormalized: new Map(),
  			materials: new Map(),
  			textures: new Map(),
  			images: new Map()
  
  		};
  
  		var cachedCanvas;
  
  		var uids = new Map();
  		var uid = 0;
  
  		/**
  		 * Assign and return a temporal unique id for an object
  		 * especially which doesn't have .uuid
  		 * @param  {Object} object
  		 * @return {Integer}
  		 */
  		function getUID( object ) {
  
  			if ( ! uids.has( object ) ) uids.set( object, uid ++ );
  
  			return uids.get( object );
  
  		}
  
  		/**
  		 * Compare two arrays
  		 * @param  {Array} array1 Array 1 to compare
  		 * @param  {Array} array2 Array 2 to compare
  		 * @return {Boolean}        Returns true if both arrays are equal
  		 */
  		function equalArray( array1, array2 ) {
  
  			return ( array1.length === array2.length ) && array1.every( function ( element, index ) {
  
  				return element === array2[ index ];
  
  			} );
  
  		}
  
  		/**
  		 * Is identity matrix
  		 *
  		 * @param {THREE.Matrix4} matrix
  		 * @returns {Boolean} Returns true, if parameter is identity matrix
  		 */
  		function isIdentityMatrix( matrix ) {
  
  			return equalArray( matrix.elements, identityArray );
  
  		}
  
  		/**
  		 * Converts a string to an ArrayBuffer.
  		 * @param  {string} text
  		 * @return {ArrayBuffer}
  		 */
  		function stringToArrayBuffer( text ) {
  
  			if ( window.TextEncoder !== undefined ) {
  
  				return new TextEncoder().encode( text ).buffer;
  
  			}
  
  			var array = new Uint8Array( new ArrayBuffer( text.length ) );
  
  			for ( var i = 0, il = text.length; i < il; i ++ ) {
  
  				var value = text.charCodeAt( i );
  
  				// Replacing multi-byte character with space(0x20).
  				array[ i ] = value > 0xFF ? 0x20 : value;
  
  			}
  
  			return array.buffer;
  
  		}
  
  		/**
  		 * Get the min and max vectors from the given attribute
  		 * @param  {THREE.BufferAttribute} attribute Attribute to find the min/max in range from start to start + count
  		 * @param  {Integer} start
  		 * @param  {Integer} count
  		 * @return {Object} Object containing the `min` and `max` values (As an array of attribute.itemSize components)
  		 */
  		function getMinMax( attribute, start, count ) {
  
  			var output = {
  
  				min: new Array( attribute.itemSize ).fill( Number.POSITIVE_INFINITY ),
  				max: new Array( attribute.itemSize ).fill( Number.NEGATIVE_INFINITY )
  
  			};
  
  			for ( var i = start; i < start + count; i ++ ) {
  
  				for ( var a = 0; a < attribute.itemSize; a ++ ) {
  
  					var value = attribute.array[ i * attribute.itemSize + a ];
  					output.min[ a ] = Math.min( output.min[ a ], value );
  					output.max[ a ] = Math.max( output.max[ a ], value );
  
  				}
  
  			}
  
  			return output;
  
  		}
  
  		/**
  		 * Checks if image size is POT.
  		 *
  		 * @param {Image} image The image to be checked.
  		 * @returns {Boolean} Returns true if image size is POT.
  		 *
  		 */
  		function isPowerOfTwo( image ) {
  
  			return THREE.MathUtils.isPowerOfTwo( image.width ) && THREE.MathUtils.isPowerOfTwo( image.height );
  
  		}
  
  		/**
  		 * Checks if normal attribute values are normalized.
  		 *
  		 * @param {THREE.BufferAttribute} normal
  		 * @returns {Boolean}
  		 *
  		 */
  		function isNormalizedNormalAttribute( normal ) {
  
  			if ( cachedData.attributesNormalized.has( normal ) ) {
  
  				return false;
  
  			}
  
  			var v = new THREE.Vector3();
  
  			for ( var i = 0, il = normal.count; i < il; i ++ ) {
  
  				// 0.0005 is from glTF-validator
  				if ( Math.abs( v.fromArray( normal.array, i * 3 ).length() - 1.0 ) > 0.0005 ) return false;
  
  			}
  
  			return true;
  
  		}
  
  		/**
  		 * Creates normalized normal buffer attribute.
  		 *
  		 * @param {THREE.BufferAttribute} normal
  		 * @returns {THREE.BufferAttribute}
  		 *
  		 */
  		function createNormalizedNormalAttribute( normal ) {
  
  			if ( cachedData.attributesNormalized.has( normal ) ) {
  
  				return cachedData.attributesNormalized.get( normal );
  
  			}
  
  			var attribute = normal.clone();
  
  			var v = new THREE.Vector3();
  
  			for ( var i = 0, il = attribute.count; i < il; i ++ ) {
  
  				v.fromArray( attribute.array, i * 3 );
  
  				if ( v.x === 0 && v.y === 0 && v.z === 0 ) {
  
  					// if values can't be normalized set (1, 0, 0)
  					v.setX( 1.0 );
  
  				} else {
  
  					v.normalize();
  
  				}
  
  				v.toArray( attribute.array, i * 3 );
  
  			}
  
  			cachedData.attributesNormalized.set( normal, attribute );
  
  			return attribute;
  
  		}
  
  		/**
  		 * Get the required size + padding for a buffer, rounded to the next 4-byte boundary.
  		 * https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#data-alignment
  		 *
  		 * @param {Integer} bufferSize The size the original buffer.
  		 * @returns {Integer} new buffer size with required padding.
  		 *
  		 */
  		function getPaddedBufferSize( bufferSize ) {
  
  			return Math.ceil( bufferSize / 4 ) * 4;
  
  		}
  
  		/**
  		 * Returns a buffer aligned to 4-byte boundary.
  		 *
  		 * @param {ArrayBuffer} arrayBuffer Buffer to pad
  		 * @param {Integer} paddingByte (Optional)
  		 * @returns {ArrayBuffer} The same buffer if it's already aligned to 4-byte boundary or a new buffer
  		 */
  		function getPaddedArrayBuffer( arrayBuffer, paddingByte ) {
  
  			paddingByte = paddingByte || 0;
  
  			var paddedLength = getPaddedBufferSize( arrayBuffer.byteLength );
  
  			if ( paddedLength !== arrayBuffer.byteLength ) {
  
  				var array = new Uint8Array( paddedLength );
  				array.set( new Uint8Array( arrayBuffer ) );
  
  				if ( paddingByte !== 0 ) {
  
  					for ( var i = arrayBuffer.byteLength; i < paddedLength; i ++ ) {
  
  						array[ i ] = paddingByte;
  
  					}
  
  				}
  
  				return array.buffer;
  
  			}
  
  			return arrayBuffer;
  
  		}
  
  		/**
  		 * Serializes a userData.
  		 *
  		 * @param {THREE.Object3D|THREE.Material} object
  		 * @param {Object} gltfProperty
  		 */
  		function serializeUserData( object, gltfProperty ) {
  
  			if ( Object.keys( object.userData ).length === 0 ) {
  
  				return;
  
  			}
  
  			try {
  
  				var json = JSON.parse( JSON.stringify( object.userData ) );
  
  				if ( options.includeCustomExtensions && json.gltfExtensions ) {
  
  					if ( gltfProperty.extensions === undefined ) {
  
  						gltfProperty.extensions = {};
  
  					}
  
  					for ( var extensionName in json.gltfExtensions ) {
  
  						gltfProperty.extensions[ extensionName ] = json.gltfExtensions[ extensionName ];
  						extensionsUsed[ extensionName ] = true;
  
  					}
  
  					delete json.gltfExtensions;
  
  				}
  
  				if ( Object.keys( json ).length > 0 ) {
  
  					gltfProperty.extras = json;
  
  				}
  
  			} catch ( error ) {
  
  				console.warn( 'THREE.GLTFExporter: userData of \'' + object.name + '\' ' +
  					'won\'t be serialized because of JSON.stringify error - ' + error.message );
  
  			}
  
  		}
  
  		/**
  		 * Applies a texture transform, if present, to the map definition. Requires
  		 * the KHR_texture_transform extension.
  		 */
  		function applyTextureTransform( mapDef, texture ) {
  
  			var didTransform = false;
  			var transformDef = {};
  
  			if ( texture.offset.x !== 0 || texture.offset.y !== 0 ) {
  
  				transformDef.offset = texture.offset.toArray();
  				didTransform = true;
  
  			}
  
  			if ( texture.rotation !== 0 ) {
  
  				transformDef.rotation = texture.rotation;
  				didTransform = true;
  
  			}
  
  			if ( texture.repeat.x !== 1 || texture.repeat.y !== 1 ) {
  
  				transformDef.scale = texture.repeat.toArray();
  				didTransform = true;
  
  			}
  
  			if ( didTransform ) {
  
  				mapDef.extensions = mapDef.extensions || {};
  				mapDef.extensions[ 'KHR_texture_transform' ] = transformDef;
  				extensionsUsed[ 'KHR_texture_transform' ] = true;
  
  			}
  
  		}
  
  		/**
  		 * Process a buffer to append to the default one.
  		 * @param  {ArrayBuffer} buffer
  		 * @return {Integer}
  		 */
  		function processBuffer( buffer ) {
  
  			if ( ! outputJSON.buffers ) {
  
  				outputJSON.buffers = [ { byteLength: 0 } ];
  
  			}
  
  			// All buffers are merged before export.
  			buffers.push( buffer );
  
  			return 0;
  
  		}
  
  		/**
  		 * Process and generate a BufferView
  		 * @param  {THREE.BufferAttribute} attribute
  		 * @param  {number} componentType
  		 * @param  {number} start
  		 * @param  {number} count
  		 * @param  {number} target (Optional) Target usage of the BufferView
  		 * @return {Object}
  		 */
  		function processBufferView( attribute, componentType, start, count, target ) {
  
  			if ( ! outputJSON.bufferViews ) {
  
  				outputJSON.bufferViews = [];
  
  			}
  
  			// Create a new dataview and dump the attribute's array into it
  
  			var componentSize;
  
  			if ( componentType === WEBGL_CONSTANTS.UNSIGNED_BYTE ) {
  
  				componentSize = 1;
  
  			} else if ( componentType === WEBGL_CONSTANTS.UNSIGNED_SHORT ) {
  
  				componentSize = 2;
  
  			} else {
  
  				componentSize = 4;
  
  			}
  
  			var byteLength = getPaddedBufferSize( count * attribute.itemSize * componentSize );
  			var dataView = new DataView( new ArrayBuffer( byteLength ) );
  			var offset = 0;
  
  			for ( var i = start; i < start + count; i ++ ) {
  
  				for ( var a = 0; a < attribute.itemSize; a ++ ) {
  
  					var value;
  
  					if ( attribute.itemSize > 4 ) {
  
  						 // no support for interleaved data for itemSize > 4
  
  						value = attribute.array[ i * attribute.itemSize + a ];
  
  					} else {
  
  						if ( a === 0 ) value = attribute.getX( i );
  						else if ( a === 1 ) value = attribute.getY( i );
  						else if ( a === 2 ) value = attribute.getZ( i );
  						else if ( a === 3 ) value = attribute.getW( i );
  
  					}
  
  					if ( componentType === WEBGL_CONSTANTS.FLOAT ) {
  
  						dataView.setFloat32( offset, value, true );
  
  					} else if ( componentType === WEBGL_CONSTANTS.UNSIGNED_INT ) {
  
  						dataView.setUint32( offset, value, true );
  
  					} else if ( componentType === WEBGL_CONSTANTS.UNSIGNED_SHORT ) {
  
  						dataView.setUint16( offset, value, true );
  
  					} else if ( componentType === WEBGL_CONSTANTS.UNSIGNED_BYTE ) {
  
  						dataView.setUint8( offset, value );
  
  					}
  
  					offset += componentSize;
  
  				}
  
  			}
  
  			var gltfBufferView = {
  
  				buffer: processBuffer( dataView.buffer ),
  				byteOffset: byteOffset,
  				byteLength: byteLength
  
  			};
  
  			if ( target !== undefined ) gltfBufferView.target = target;
  
  			if ( target === WEBGL_CONSTANTS.ARRAY_BUFFER ) {
  
  				// Only define byteStride for vertex attributes.
  				gltfBufferView.byteStride = attribute.itemSize * componentSize;
  
  			}
  
  			byteOffset += byteLength;
  
  			outputJSON.bufferViews.push( gltfBufferView );
  
  			// @TODO Merge bufferViews where possible.
  			var output = {
  
  				id: outputJSON.bufferViews.length - 1,
  				byteLength: 0
  
  			};
  
  			return output;
  
  		}
  
  		/**
  		 * Process and generate a BufferView from an image Blob.
  		 * @param {Blob} blob
  		 * @return {Promise<Integer>}
  		 */
  		function processBufferViewImage( blob ) {
  
  			if ( ! outputJSON.bufferViews ) {
  
  				outputJSON.bufferViews = [];
  
  			}
  
  			return new Promise( function ( resolve ) {
  
  				var reader = new window.FileReader();
  				reader.readAsArrayBuffer( blob );
  				reader.onloadend = function () {
  
  					var buffer = getPaddedArrayBuffer( reader.result );
  
  					var bufferView = {
  						buffer: processBuffer( buffer ),
  						byteOffset: byteOffset,
  						byteLength: buffer.byteLength
  					};
  
  					byteOffset += buffer.byteLength;
  
  					outputJSON.bufferViews.push( bufferView );
  
  					resolve( outputJSON.bufferViews.length - 1 );
  
  				};
  
  			} );
  
  		}
  
  		/**
  		 * Process attribute to generate an accessor
  		 * @param  {THREE.BufferAttribute} attribute Attribute to process
  		 * @param  {THREE.BufferGeometry} geometry (Optional) Geometry used for truncated draw range
  		 * @param  {Integer} start (Optional)
  		 * @param  {Integer} count (Optional)
  		 * @return {Integer}           Index of the processed accessor on the "accessors" array
  		 */
  		function processAccessor( attribute, geometry, start, count ) {
  
  			var types = {
  
  				1: 'SCALAR',
  				2: 'VEC2',
  				3: 'VEC3',
  				4: 'VEC4',
  				16: 'MAT4'
  
  			};
  
  			var componentType;
  
  			// Detect the component type of the attribute array (float, uint or ushort)
  			if ( attribute.array.constructor === Float32Array ) {
  
  				componentType = WEBGL_CONSTANTS.FLOAT;
  
  			} else if ( attribute.array.constructor === Uint32Array ) {
  
  				componentType = WEBGL_CONSTANTS.UNSIGNED_INT;
  
  			} else if ( attribute.array.constructor === Uint16Array ) {
  
  				componentType = WEBGL_CONSTANTS.UNSIGNED_SHORT;
  
  			} else if ( attribute.array.constructor === Uint8Array ) {
  
  				componentType = WEBGL_CONSTANTS.UNSIGNED_BYTE;
  
  			} else {
  
  				throw new Error( 'THREE.GLTFExporter: Unsupported bufferAttribute component type.' );
  
  			}
  
  			if ( start === undefined ) start = 0;
  			if ( count === undefined ) count = attribute.count;
  
  			// @TODO Indexed buffer geometry with drawRange not supported yet
  			if ( options.truncateDrawRange && geometry !== undefined && geometry.index === null ) {
  
  				var end = start + count;
  				var end2 = geometry.drawRange.count === Infinity
  					? attribute.count
  					: geometry.drawRange.start + geometry.drawRange.count;
  
  				start = Math.max( start, geometry.drawRange.start );
  				count = Math.min( end, end2 ) - start;
  
  				if ( count < 0 ) count = 0;
  
  			}
  
  			// Skip creating an accessor if the attribute doesn't have data to export
  			if ( count === 0 ) {
  
  				return null;
  
  			}
  
  			var minMax = getMinMax( attribute, start, count );
  
  			var bufferViewTarget;
  
  			// If geometry isn't provided, don't infer the target usage of the bufferView. For
  			// animation samplers, target must not be set.
  			if ( geometry !== undefined ) {
  
  				bufferViewTarget = attribute === geometry.index ? WEBGL_CONSTANTS.ELEMENT_ARRAY_BUFFER : WEBGL_CONSTANTS.ARRAY_BUFFER;
  
  			}
  
  			var bufferView = processBufferView( attribute, componentType, start, count, bufferViewTarget );
  
  			var gltfAccessor = {
  
  				bufferView: bufferView.id,
  				byteOffset: bufferView.byteOffset,
  				componentType: componentType,
  				count: count,
  				max: minMax.max,
  				min: minMax.min,
  				type: types[ attribute.itemSize ]
  
  			};
  
  			if ( attribute.normalized === true ) {
  
  				gltfAccessor.normalized = true;
  
  			}
  
  			if ( ! outputJSON.accessors ) {
  
  				outputJSON.accessors = [];
  
  			}
  
  			outputJSON.accessors.push( gltfAccessor );
  
  			return outputJSON.accessors.length - 1;
  
  		}
  
  		/**
  		 * Process image
  		 * @param  {Image} image to process
  		 * @param  {Integer} format of the image (e.g. THREE.RGBFormat, THREE.RGBAFormat etc)
  		 * @param  {Boolean} flipY before writing out the image
  		 * @return {Integer}     Index of the processed texture in the "images" array
  		 */
  		function processImage( image, format, flipY ) {
  
  			if ( ! cachedData.images.has( image ) ) {
  
  				cachedData.images.set( image, {} );
  
  			}
  
  			var cachedImages = cachedData.images.get( image );
  			var mimeType = format === THREE.RGBAFormat ? 'image/png' : 'image/jpeg';
  			var key = mimeType + ":flipY/" + flipY.toString();
  
  			if ( cachedImages[ key ] !== undefined ) {
  
  				return cachedImages[ key ];
  
  			}
  
  			if ( ! outputJSON.images ) {
  
  				outputJSON.images = [];
  
  			}
  
  			var gltfImage = { mimeType: mimeType };
  
  			if ( options.embedImages ) {
  
  				var canvas = cachedCanvas = cachedCanvas || document.createElement( 'canvas' );
  
  				canvas.width = Math.min( image.width, options.maxTextureSize );
  				canvas.height = Math.min( image.height, options.maxTextureSize );
  
  				if ( options.forcePowerOfTwoTextures && ! isPowerOfTwo( canvas ) ) {
  
  					console.warn( 'GLTFExporter: Resized non-power-of-two image.', image );
  
  					canvas.width = THREE.MathUtils.floorPowerOfTwo( canvas.width );
  					canvas.height = THREE.MathUtils.floorPowerOfTwo( canvas.height );
  
  				}
  
  				var ctx = canvas.getContext( '2d' );
  
  				if ( flipY === true ) {
  
  					ctx.translate( 0, canvas.height );
  					ctx.scale( 1, - 1 );
  
  				}
  
  				ctx.drawImage( image, 0, 0, canvas.width, canvas.height );
  
  				if ( options.binary === true ) {
  
  					pending.push( new Promise( function ( resolve ) {
  
  						canvas.toBlob( function ( blob ) {
  
  							processBufferViewImage( blob ).then( function ( bufferViewIndex ) {
  
  								gltfImage.bufferView = bufferViewIndex;
  
  								resolve();
  
  							} );
  
  						}, mimeType );
  
  					} ) );
  
  				} else {
  
  					gltfImage.uri = canvas.toDataURL( mimeType );
  
  				}
  
  			} else {
  
  				gltfImage.uri = image.src;
  
  			}
  
  			outputJSON.images.push( gltfImage );
  
  			var index = outputJSON.images.length - 1;
  			cachedImages[ key ] = index;
  
  			return index;
  
  		}
  
  		/**
  		 * Process sampler
  		 * @param  {Texture} map Texture to process
  		 * @return {Integer}     Index of the processed texture in the "samplers" array
  		 */
  		function processSampler( map ) {
  
  			if ( ! outputJSON.samplers ) {
  
  				outputJSON.samplers = [];
  
  			}
  
  			var gltfSampler = {
  
  				magFilter: THREE_TO_WEBGL[ map.magFilter ],
  				minFilter: THREE_TO_WEBGL[ map.minFilter ],
  				wrapS: THREE_TO_WEBGL[ map.wrapS ],
  				wrapT: THREE_TO_WEBGL[ map.wrapT ]
  
  			};
  
  			outputJSON.samplers.push( gltfSampler );
  
  			return outputJSON.samplers.length - 1;
  
  		}
  
  		/**
  		 * Process texture
  		 * @param  {Texture} map Map to process
  		 * @return {Integer}     Index of the processed texture in the "textures" array
  		 */
  		function processTexture( map ) {
  
  			if ( cachedData.textures.has( map ) ) {
  
  				return cachedData.textures.get( map );
  
  			}
  
  			if ( ! outputJSON.textures ) {
  
  				outputJSON.textures = [];
  
  			}
  
  			var gltfTexture = {
  
  				sampler: processSampler( map ),
  				source: processImage( map.image, map.format, map.flipY )
  
  			};
  
  			if ( map.name ) {
  
  				gltfTexture.name = map.name;
  
  			}
  
  			outputJSON.textures.push( gltfTexture );
  
  			var index = outputJSON.textures.length - 1;
  			cachedData.textures.set( map, index );
  
  			return index;
  
  		}
  
  		/**
  		 * Process material
  		 * @param  {THREE.Material} material Material to process
  		 * @return {Integer}      Index of the processed material in the "materials" array
  		 */
  		function processMaterial( material ) {
  
  			if ( cachedData.materials.has( material ) ) {
  
  				return cachedData.materials.get( material );
  
  			}
  
  			if ( material.isShaderMaterial ) {
  
  				console.warn( 'GLTFExporter: THREE.ShaderMaterial not supported.' );
  				return null;
  
  			}
  
  			if ( ! outputJSON.materials ) {
  
  				outputJSON.materials = [];
  
  			}
  
  			// @QUESTION Should we avoid including any attribute that has the default value?
  			var gltfMaterial = {
  
  				pbrMetallicRoughness: {}
  
  			};
  
  			if ( material.isMeshBasicMaterial ) {
  
  				gltfMaterial.extensions = { KHR_materials_unlit: {} };
  
  				extensionsUsed[ 'KHR_materials_unlit' ] = true;
  
  			} else if ( material.isGLTFSpecularGlossinessMaterial ) {
  
  				gltfMaterial.extensions = { KHR_materials_pbrSpecularGlossiness: {} };
  
  				extensionsUsed[ 'KHR_materials_pbrSpecularGlossiness' ] = true;
  
  			} else if ( ! material.isMeshStandardMaterial ) {
  
  				console.warn( 'GLTFExporter: Use MeshStandardMaterial or MeshBasicMaterial for best results.' );
  
  			}
  
  			// pbrMetallicRoughness.baseColorFactor
  			var color = material.color.toArray().concat( [ material.opacity ] );
  
  			if ( ! equalArray( color, [ 1, 1, 1, 1 ] ) ) {
  
  				gltfMaterial.pbrMetallicRoughness.baseColorFactor = color;
  
  			}
  
  			if ( material.isMeshStandardMaterial ) {
  
  				gltfMaterial.pbrMetallicRoughness.metallicFactor = material.metalness;
  				gltfMaterial.pbrMetallicRoughness.roughnessFactor = material.roughness;
  
  			} else if ( material.isMeshBasicMaterial ) {
  
  				gltfMaterial.pbrMetallicRoughness.metallicFactor = 0.0;
  				gltfMaterial.pbrMetallicRoughness.roughnessFactor = 0.9;
  
  			} else {
  
  				gltfMaterial.pbrMetallicRoughness.metallicFactor = 0.5;
  				gltfMaterial.pbrMetallicRoughness.roughnessFactor = 0.5;
  
  			}
  
  			// pbrSpecularGlossiness diffuse, specular and glossiness factor
  			if ( material.isGLTFSpecularGlossinessMaterial ) {
  
  				if ( gltfMaterial.pbrMetallicRoughness.baseColorFactor ) {
  
  					gltfMaterial.extensions.KHR_materials_pbrSpecularGlossiness.diffuseFactor = gltfMaterial.pbrMetallicRoughness.baseColorFactor;
  
  				}
  
  				var specularFactor = [ 1, 1, 1 ];
  				material.specular.toArray( specularFactor, 0 );
  				gltfMaterial.extensions.KHR_materials_pbrSpecularGlossiness.specularFactor = specularFactor;
  
  				gltfMaterial.extensions.KHR_materials_pbrSpecularGlossiness.glossinessFactor = material.glossiness;
  
  			}
  
  			// pbrMetallicRoughness.metallicRoughnessTexture
  			if ( material.metalnessMap || material.roughnessMap ) {
  
  				if ( material.metalnessMap === material.roughnessMap ) {
  
  					var metalRoughMapDef = { index: processTexture( material.metalnessMap ) };
  					applyTextureTransform( metalRoughMapDef, material.metalnessMap );
  					gltfMaterial.pbrMetallicRoughness.metallicRoughnessTexture = metalRoughMapDef;
  
  				} else {
  
  					console.warn( 'THREE.GLTFExporter: Ignoring metalnessMap and roughnessMap because they are not the same Texture.' );
  
  				}
  
  			}
  
  			// pbrMetallicRoughness.baseColorTexture or pbrSpecularGlossiness diffuseTexture
  			if ( material.map ) {
  
  				var baseColorMapDef = { index: processTexture( material.map ) };
  				applyTextureTransform( baseColorMapDef, material.map );
  
  				if ( material.isGLTFSpecularGlossinessMaterial ) {
  
  					gltfMaterial.extensions.KHR_materials_pbrSpecularGlossiness.diffuseTexture = baseColorMapDef;
  
  				}
  
  				gltfMaterial.pbrMetallicRoughness.baseColorTexture = baseColorMapDef;
  
  			}
  
  			// pbrSpecularGlossiness specular map
  			if ( material.isGLTFSpecularGlossinessMaterial && material.specularMap ) {
  
  				var specularMapDef = { index: processTexture( material.specularMap ) };
  				applyTextureTransform( specularMapDef, material.specularMap );
  				gltfMaterial.extensions.KHR_materials_pbrSpecularGlossiness.specularGlossinessTexture = specularMapDef;
  
  			}
  
  			if ( material.emissive ) {
  
  				// emissiveFactor
  				var emissive = material.emissive.clone().multiplyScalar( material.emissiveIntensity ).toArray();
  
  				if ( ! equalArray( emissive, [ 0, 0, 0 ] ) ) {
  
  					gltfMaterial.emissiveFactor = emissive;
  
  				}
  
  				// emissiveTexture
  				if ( material.emissiveMap ) {
  
  					var emissiveMapDef = { index: processTexture( material.emissiveMap ) };
  					applyTextureTransform( emissiveMapDef, material.emissiveMap );
  					gltfMaterial.emissiveTexture = emissiveMapDef;
  
  				}
  
  			}
  
  			// normalTexture
  			if ( material.normalMap ) {
  
  				var normalMapDef = { index: processTexture( material.normalMap ) };
  
  				if ( material.normalScale && material.normalScale.x !== - 1 ) {
  
  					if ( material.normalScale.x !== material.normalScale.y ) {
  
  						console.warn( 'THREE.GLTFExporter: Normal scale components are different, ignoring Y and exporting X.' );
  
  					}
  
  					normalMapDef.scale = material.normalScale.x;
  
  				}
  
  				applyTextureTransform( normalMapDef, material.normalMap );
  
  				gltfMaterial.normalTexture = normalMapDef;
  
  			}
  
  			// occlusionTexture
  			if ( material.aoMap ) {
  
  				var occlusionMapDef = {
  					index: processTexture( material.aoMap ),
  					texCoord: 1
  				};
  
  				if ( material.aoMapIntensity !== 1.0 ) {
  
  					occlusionMapDef.strength = material.aoMapIntensity;
  
  				}
  
  				applyTextureTransform( occlusionMapDef, material.aoMap );
  
  				gltfMaterial.occlusionTexture = occlusionMapDef;
  
  			}
  
  			// alphaMode
  			if ( material.transparent ) {
  
  				gltfMaterial.alphaMode = 'BLEND';
  
  			} else {
  
  				if ( material.alphaTest > 0.0 ) {
  
  					gltfMaterial.alphaMode = 'MASK';
  					gltfMaterial.alphaCutoff = material.alphaTest;
  
  				}
  
  			}
  
  			// doubleSided
  			if ( material.side === THREE.DoubleSide ) {
  
  				gltfMaterial.doubleSided = true;
  
  			}
  
  			if ( material.name !== '' ) {
  
  				gltfMaterial.name = material.name;
  
  			}
  
  			serializeUserData( material, gltfMaterial );
  
  			outputJSON.materials.push( gltfMaterial );
  
  			var index = outputJSON.materials.length - 1;
  			cachedData.materials.set( material, index );
  
  			return index;
  
  		}
  
  		/**
  		 * Process mesh
  		 * @param  {THREE.Mesh} mesh Mesh to process
  		 * @return {Integer}      Index of the processed mesh in the "meshes" array
  		 */
  		function processMesh( mesh ) {
  
  			var meshCacheKeyParts = [ mesh.geometry.uuid ];
  			if ( Array.isArray( mesh.material ) ) {
  
  				for ( var i = 0, l = mesh.material.length; i < l; i ++ ) {
  
  					meshCacheKeyParts.push( mesh.material[ i ].uuid	);
  
  				}
  
  			} else {
  
  				meshCacheKeyParts.push( mesh.material.uuid );
  
  			}
  
  			var meshCacheKey = meshCacheKeyParts.join( ':' );
  			if ( cachedData.meshes.has( meshCacheKey ) ) {
  
  				return cachedData.meshes.get( meshCacheKey );
  
  			}
  
  			var geometry = mesh.geometry;
  
  			var mode;
  
  			// Use the correct mode
  			if ( mesh.isLineSegments ) {
  
  				mode = WEBGL_CONSTANTS.LINES;
  
  			} else if ( mesh.isLineLoop ) {
  
  				mode = WEBGL_CONSTANTS.LINE_LOOP;
  
  			} else if ( mesh.isLine ) {
  
  				mode = WEBGL_CONSTANTS.LINE_STRIP;
  
  			} else if ( mesh.isPoints ) {
  
  				mode = WEBGL_CONSTANTS.POINTS;
  
  			} else {
  
  				mode = mesh.material.wireframe ? WEBGL_CONSTANTS.LINES : WEBGL_CONSTANTS.TRIANGLES;
  
  			}
  
  			if ( ! geometry.isBufferGeometry ) {
  
  				console.warn( 'GLTFExporter: Exporting THREE.Geometry will increase file size. Use THREE.BufferGeometry instead.' );
  				geometry = new THREE.BufferGeometry().setFromObject( mesh );
  
  			}
  
  			var gltfMesh = {};
  
  			var attributes = {};
  			var primitives = [];
  			var targets = [];
  
  			// Conversion between attributes names in threejs and gltf spec
  			var nameConversion = {
  
  				uv: 'TEXCOORD_0',
  				uv2: 'TEXCOORD_1',
  				color: 'COLOR_0',
  				skinWeight: 'WEIGHTS_0',
  				skinIndex: 'JOINTS_0'
  
  			};
  
  			var originalNormal = geometry.getAttribute( 'normal' );
  
  			if ( originalNormal !== undefined && ! isNormalizedNormalAttribute( originalNormal ) ) {
  
  				console.warn( 'THREE.GLTFExporter: Creating normalized normal attribute from the non-normalized one.' );
  
  				geometry.setAttribute( 'normal', createNormalizedNormalAttribute( originalNormal ) );
  
  			}
  
  			// @QUESTION Detect if .vertexColors = true?
  			// For every attribute create an accessor
  			var modifiedAttribute = null;
  			for ( var attributeName in geometry.attributes ) {
  
  				// Ignore morph target attributes, which are exported later.
  				if ( attributeName.substr( 0, 5 ) === 'morph' ) continue;
  
  				var attribute = geometry.attributes[ attributeName ];
  				attributeName = nameConversion[ attributeName ] || attributeName.toUpperCase();
  
  				// Prefix all geometry attributes except the ones specifically
  				// listed in the spec; non-spec attributes are considered custom.
  				var validVertexAttributes =
  						/^(POSITION|NORMAL|TANGENT|TEXCOORD_\d+|COLOR_\d+|JOINTS_\d+|WEIGHTS_\d+)$/;
  				if ( ! validVertexAttributes.test( attributeName ) ) {
  
  					attributeName = '_' + attributeName;
  
  				}
  
  				if ( cachedData.attributes.has( getUID( attribute ) ) ) {
  
  					attributes[ attributeName ] = cachedData.attributes.get( getUID( attribute ) );
  					continue;
  
  				}
  
  				// JOINTS_0 must be UNSIGNED_BYTE or UNSIGNED_SHORT.
  				modifiedAttribute = null;
  				var array = attribute.array;
  				if ( attributeName === 'JOINTS_0' &&
  					! ( array instanceof Uint16Array ) &&
  					! ( array instanceof Uint8Array ) ) {
  
  					console.warn( 'GLTFExporter: Attribute "skinIndex" converted to type UNSIGNED_SHORT.' );
  					modifiedAttribute = new THREE.BufferAttribute( new Uint16Array( array ), attribute.itemSize, attribute.normalized );
  
  				}
  
  				var accessor = processAccessor( modifiedAttribute || attribute, geometry );
  				if ( accessor !== null ) {
  
  					attributes[ attributeName ] = accessor;
  					cachedData.attributes.set( getUID( attribute ), accessor );
  
  				}
  
  			}
  
  			if ( originalNormal !== undefined ) geometry.setAttribute( 'normal', originalNormal );
  
  			// Skip if no exportable attributes found
  			if ( Object.keys( attributes ).length === 0 ) {
  
  				return null;
  
  			}
  
  			// Morph targets
  			if ( mesh.morphTargetInfluences !== undefined && mesh.morphTargetInfluences.length > 0 ) {
  
  				var weights = [];
  				var targetNames = [];
  				var reverseDictionary = {};
  
  				if ( mesh.morphTargetDictionary !== undefined ) {
  
  					for ( var key in mesh.morphTargetDictionary ) {
  
  						reverseDictionary[ mesh.morphTargetDictionary[ key ] ] = key;
  
  					}
  
  				}
  
  				for ( var i = 0; i < mesh.morphTargetInfluences.length; ++ i ) {
  
  					var target = {};
  
  					var warned = false;
  
  					for ( var attributeName in geometry.morphAttributes ) {
  
  						// glTF 2.0 morph supports only POSITION/NORMAL/TANGENT.
  						// Three.js doesn't support TANGENT yet.
  
  						if ( attributeName !== 'position' && attributeName !== 'normal' ) {
  
  							if ( ! warned ) {
  
  								console.warn( 'GLTFExporter: Only POSITION and NORMAL morph are supported.' );
  								warned = true;
  
  							}
  
  							continue;
  
  						}
  
  						var attribute = geometry.morphAttributes[ attributeName ][ i ];
  						var gltfAttributeName = attributeName.toUpperCase();
  
  						// Three.js morph attribute has absolute values while the one of glTF has relative values.
  						//
  						// glTF 2.0 Specification:
  						// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#morph-targets
  
  						var baseAttribute = geometry.attributes[ attributeName ];
  
  						if ( cachedData.attributes.has( getUID( attribute ) ) ) {
  
  							target[ gltfAttributeName ] = cachedData.attributes.get( getUID( attribute ) );
  							continue;
  
  						}
  
  						// Clones attribute not to override
  						var relativeAttribute = attribute.clone();
  
  						if ( ! geometry.morphTargetsRelative ) {
  
  							for ( var j = 0, jl = attribute.count; j < jl; j ++ ) {
  
  								relativeAttribute.setXYZ(
  									j,
  									attribute.getX( j ) - baseAttribute.getX( j ),
  									attribute.getY( j ) - baseAttribute.getY( j ),
  									attribute.getZ( j ) - baseAttribute.getZ( j )
  								);
  
  							}
  
  						}
  
  						target[ gltfAttributeName ] = processAccessor( relativeAttribute, geometry );
  						cachedData.attributes.set( getUID( baseAttribute ), target[ gltfAttributeName ] );
  
  					}
  
  					targets.push( target );
  
  					weights.push( mesh.morphTargetInfluences[ i ] );
  					if ( mesh.morphTargetDictionary !== undefined ) targetNames.push( reverseDictionary[ i ] );
  
  				}
  
  				gltfMesh.weights = weights;
  
  				if ( targetNames.length > 0 ) {
  
  					gltfMesh.extras = {};
  					gltfMesh.extras.targetNames = targetNames;
  
  				}
  
  			}
  
  			var isMultiMaterial = Array.isArray( mesh.material );
  
  			if ( isMultiMaterial && geometry.groups.length === 0 ) return null;
  
  			var materials = isMultiMaterial ? mesh.material : [ mesh.material ];
  			var groups = isMultiMaterial ? geometry.groups : [ { materialIndex: 0, start: undefined, count: undefined } ];
  
  			for ( var i = 0, il = groups.length; i < il; i ++ ) {
  
  				var primitive = {
  					mode: mode,
  					attributes: attributes,
  				};
  
  				serializeUserData( geometry, primitive );
  
  				if ( targets.length > 0 ) primitive.targets = targets;
  
  				if ( geometry.index !== null ) {
  
  					var cacheKey = getUID( geometry.index );
  
  					if ( groups[ i ].start !== undefined || groups[ i ].count !== undefined ) {
  
  						cacheKey += ':' + groups[ i ].start + ':' + groups[ i ].count;
  
  					}
  
  					if ( cachedData.attributes.has( cacheKey ) ) {
  
  						primitive.indices = cachedData.attributes.get( cacheKey );
  
  					} else {
  
  						primitive.indices = processAccessor( geometry.index, geometry, groups[ i ].start, groups[ i ].count );
  						cachedData.attributes.set( cacheKey, primitive.indices );
  
  					}
  
  					if ( primitive.indices === null ) delete primitive.indices;
  
  				}
  
  				var material = processMaterial( materials[ groups[ i ].materialIndex ] );
  
  				if ( material !== null ) {
  
  					primitive.material = material;
  
  				}
  
  				primitives.push( primitive );
  
  			}
  
  			gltfMesh.primitives = primitives;
  
  			if ( ! outputJSON.meshes ) {
  
  				outputJSON.meshes = [];
  
  			}
  
  			outputJSON.meshes.push( gltfMesh );
  
  			var index = outputJSON.meshes.length - 1;
  			cachedData.meshes.set( meshCacheKey, index );
  
  			return index;
  
  		}
  
  		/**
  		 * Process camera
  		 * @param  {THREE.Camera} camera Camera to process
  		 * @return {Integer}      Index of the processed mesh in the "camera" array
  		 */
  		function processCamera( camera ) {
  
  			if ( ! outputJSON.cameras ) {
  
  				outputJSON.cameras = [];
  
  			}
  
  			var isOrtho = camera.isOrthographicCamera;
  
  			var gltfCamera = {
  
  				type: isOrtho ? 'orthographic' : 'perspective'
  
  			};
  
  			if ( isOrtho ) {
  
  				gltfCamera.orthographic = {
  
  					xmag: camera.right * 2,
  					ymag: camera.top * 2,
  					zfar: camera.far <= 0 ? 0.001 : camera.far,
  					znear: camera.near < 0 ? 0 : camera.near
  
  				};
  
  			} else {
  
  				gltfCamera.perspective = {
  
  					aspectRatio: camera.aspect,
  					yfov: THREE.MathUtils.degToRad( camera.fov ),
  					zfar: camera.far <= 0 ? 0.001 : camera.far,
  					znear: camera.near < 0 ? 0 : camera.near
  
  				};
  
  			}
  
  			if ( camera.name !== '' ) {
  
  				gltfCamera.name = camera.type;
  
  			}
  
  			outputJSON.cameras.push( gltfCamera );
  
  			return outputJSON.cameras.length - 1;
  
  		}
  
  		/**
  		 * Creates glTF animation entry from AnimationClip object.
  		 *
  		 * Status:
  		 * - Only properties listed in PATH_PROPERTIES may be animated.
  		 *
  		 * @param {THREE.AnimationClip} clip
  		 * @param {THREE.Object3D} root
  		 * @return {number}
  		 */
  		function processAnimation( clip, root ) {
  
  			if ( ! outputJSON.animations ) {
  
  				outputJSON.animations = [];
  
  			}
  
  			clip = THREE.GLTFExporter.Utils.mergeMorphTargetTracks( clip.clone(), root );
  
  			var tracks = clip.tracks;
  			var channels = [];
  			var samplers = [];
  
  			for ( var i = 0; i < tracks.length; ++ i ) {
  
  				var track = tracks[ i ];
  				var trackBinding = THREE.PropertyBinding.parseTrackName( track.name );
  				var trackNode = THREE.PropertyBinding.findNode( root, trackBinding.nodeName );
  				var trackProperty = PATH_PROPERTIES[ trackBinding.propertyName ];
  
  				if ( trackBinding.objectName === 'bones' ) {
  
  					if ( trackNode.isSkinnedMesh === true ) {
  
  						trackNode = trackNode.skeleton.getBoneByName( trackBinding.objectIndex );
  
  					} else {
  
  						trackNode = undefined;
  
  					}
  
  				}
  
  				if ( ! trackNode || ! trackProperty ) {
  
  					console.warn( 'THREE.GLTFExporter: Could not export animation track "%s".', track.name );
  					return null;
  
  				}
  
  				var inputItemSize = 1;
  				var outputItemSize = track.values.length / track.times.length;
  
  				if ( trackProperty === PATH_PROPERTIES.morphTargetInfluences ) {
  
  					outputItemSize /= trackNode.morphTargetInfluences.length;
  
  				}
  
  				var interpolation;
  
  				// @TODO export CubicInterpolant(InterpolateSmooth) as CUBICSPLINE
  
  				// Detecting glTF cubic spline interpolant by checking factory method's special property
  				// GLTFCubicSplineInterpolant is a custom interpolant and track doesn't return
  				// valid value from .getInterpolation().
  				if ( track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline === true ) {
  
  					interpolation = 'CUBICSPLINE';
  
  					// itemSize of CUBICSPLINE keyframe is 9
  					// (VEC3 * 3: inTangent, splineVertex, and outTangent)
  					// but needs to be stored as VEC3 so dividing by 3 here.
  					outputItemSize /= 3;
  
  				} else if ( track.getInterpolation() === THREE.InterpolateDiscrete ) {
  
  					interpolation = 'STEP';
  
  				} else {
  
  					interpolation = 'LINEAR';
  
  				}
  
  				samplers.push( {
  
  					input: processAccessor( new THREE.BufferAttribute( track.times, inputItemSize ) ),
  					output: processAccessor( new THREE.BufferAttribute( track.values, outputItemSize ) ),
  					interpolation: interpolation
  
  				} );
  
  				channels.push( {
  
  					sampler: samplers.length - 1,
  					target: {
  						node: nodeMap.get( trackNode ),
  						path: trackProperty
  					}
  
  				} );
  
  			}
  
  			outputJSON.animations.push( {
  
  				name: clip.name || 'clip_' + outputJSON.animations.length,
  				samplers: samplers,
  				channels: channels
  
  			} );
  
  			return outputJSON.animations.length - 1;
  
  		}
  
  		function processSkin( object ) {
  
  			var node = outputJSON.nodes[ nodeMap.get( object ) ];
  
  			var skeleton = object.skeleton;
  
  			if ( skeleton === undefined ) return null;
  
  			var rootJoint = object.skeleton.bones[ 0 ];
  
  			if ( rootJoint === undefined ) return null;
  
  			var joints = [];
  			var inverseBindMatrices = new Float32Array( skeleton.bones.length * 16 );
  
  			for ( var i = 0; i < skeleton.bones.length; ++ i ) {
  
  				joints.push( nodeMap.get( skeleton.bones[ i ] ) );
  
  				skeleton.boneInverses[ i ].toArray( inverseBindMatrices, i * 16 );
  
  			}
  
  			if ( outputJSON.skins === undefined ) {
  
  				outputJSON.skins = [];
  
  			}
  
  			outputJSON.skins.push( {
  
  				inverseBindMatrices: processAccessor( new THREE.BufferAttribute( inverseBindMatrices, 16 ) ),
  				joints: joints,
  				skeleton: nodeMap.get( rootJoint )
  
  			} );
  
  			var skinIndex = node.skin = outputJSON.skins.length - 1;
  
  			return skinIndex;
  
  		}
  
  		function processLight( light ) {
  
  			var lightDef = {};
  
  			if ( light.name ) lightDef.name = light.name;
  
  			lightDef.color = light.color.toArray();
  
  			lightDef.intensity = light.intensity;
  
  			if ( light.isDirectionalLight ) {
  
  				lightDef.type = 'directional';
  
  			} else if ( light.isPointLight ) {
  
  				lightDef.type = 'point';
  				if ( light.distance > 0 ) lightDef.range = light.distance;
  
  			} else if ( light.isSpotLight ) {
  
  				lightDef.type = 'spot';
  				if ( light.distance > 0 ) lightDef.range = light.distance;
  				lightDef.spot = {};
  				lightDef.spot.innerConeAngle = ( light.penumbra - 1.0 ) * light.angle * - 1.0;
  				lightDef.spot.outerConeAngle = light.angle;
  
  			}
  
  			if ( light.decay !== undefined && light.decay !== 2 ) {
  
  				console.warn( 'THREE.GLTFExporter: Light decay may be lost. glTF is physically-based, '
  					+ 'and expects light.decay=2.' );
  
  			}
  
  			if ( light.target
  					&& ( light.target.parent !== light
  					 || light.target.position.x !== 0
  					 || light.target.position.y !== 0
  					 || light.target.position.z !== - 1 ) ) {
  
  				console.warn( 'THREE.GLTFExporter: Light direction may be lost. For best results, '
  					+ 'make light.target a child of the light with position 0,0,-1.' );
  
  			}
  
  			var lights = outputJSON.extensions[ 'KHR_lights_punctual' ].lights;
  			lights.push( lightDef );
  			return lights.length - 1;
  
  		}
  
  		/**
  		 * Process Object3D node
  		 * @param  {THREE.Object3D} node Object3D to processNode
  		 * @return {Integer}      Index of the node in the nodes list
  		 */
  		function processNode( object ) {
  
  			if ( ! outputJSON.nodes ) {
  
  				outputJSON.nodes = [];
  
  			}
  
  			var gltfNode = {};
  
  			if ( options.trs ) {
  
  				var rotation = object.quaternion.toArray();
  				var position = object.position.toArray();
  				var scale = object.scale.toArray();
  
  				if ( ! equalArray( rotation, [ 0, 0, 0, 1 ] ) ) {
  
  					gltfNode.rotation = rotation;
  
  				}
  
  				if ( ! equalArray( position, [ 0, 0, 0 ] ) ) {
  
  					gltfNode.translation = position;
  
  				}
  
  				if ( ! equalArray( scale, [ 1, 1, 1 ] ) ) {
  
  					gltfNode.scale = scale;
  
  				}
  
  			} else {
  
  				if ( object.matrixAutoUpdate ) {
  
  					object.updateMatrix();
  
  				}
  
  				if ( isIdentityMatrix( object.matrix ) === false ) {
  
  					gltfNode.matrix = object.matrix.elements;
  
  				}
  
  			}
  
  			// We don't export empty strings name because it represents no-name in Three.js.
  			if ( object.name !== '' ) {
  
  				gltfNode.name = String( object.name );
  
  			}
  
  			serializeUserData( object, gltfNode );
  
  			if ( object.isMesh || object.isLine || object.isPoints ) {
  
  				var mesh = processMesh( object );
  
  				if ( mesh !== null ) {
  
  					gltfNode.mesh = mesh;
  
  				}
  
  			} else if ( object.isCamera ) {
  
  				gltfNode.camera = processCamera( object );
  
  			} else if ( object.isDirectionalLight || object.isPointLight || object.isSpotLight ) {
  
  				if ( ! extensionsUsed[ 'KHR_lights_punctual' ] ) {
  
  					outputJSON.extensions = outputJSON.extensions || {};
  					outputJSON.extensions[ 'KHR_lights_punctual' ] = { lights: [] };
  					extensionsUsed[ 'KHR_lights_punctual' ] = true;
  
  				}
  
  				gltfNode.extensions = gltfNode.extensions || {};
  				gltfNode.extensions[ 'KHR_lights_punctual' ] = { light: processLight( object ) };
  
  			} else if ( object.isLight ) {
  
  				console.warn( 'THREE.GLTFExporter: Only directional, point, and spot lights are supported.', object );
  				return null;
  
  			}
  
  			if ( object.isSkinnedMesh ) {
  
  				skins.push( object );
  
  			}
  
  			if ( object.children.length > 0 ) {
  
  				var children = [];
  
  				for ( var i = 0, l = object.children.length; i < l; i ++ ) {
  
  					var child = object.children[ i ];
  
  					if ( child.visible || options.onlyVisible === false ) {
  
  						var node = processNode( child );
  
  						if ( node !== null ) {
  
  							children.push( node );
  
  						}
  
  					}
  
  				}
  
  				if ( children.length > 0 ) {
  
  					gltfNode.children = children;
  
  				}
  
  
  			}
  
  			outputJSON.nodes.push( gltfNode );
  
  			var nodeIndex = outputJSON.nodes.length - 1;
  			nodeMap.set( object, nodeIndex );
  
  			return nodeIndex;
  
  		}
  
  		/**
  		 * Process Scene
  		 * @param  {THREE.Scene} node Scene to process
  		 */
  		function processScene( scene ) {
  
  			if ( ! outputJSON.scenes ) {
  
  				outputJSON.scenes = [];
  				outputJSON.scene = 0;
  
  			}
  
  			var gltfScene = {};
  
  			if ( scene.name !== '' ) {
  
  				gltfScene.name = scene.name;
  
  			}
  
  			outputJSON.scenes.push( gltfScene );
  
  			var nodes = [];
  
  			for ( var i = 0, l = scene.children.length; i < l; i ++ ) {
  
  				var child = scene.children[ i ];
  
  				if ( child.visible || options.onlyVisible === false ) {
  
  					var node = processNode( child );
  
  					if ( node !== null ) {
  
  						nodes.push( node );
  
  					}
  
  				}
  
  			}
  
  			if ( nodes.length > 0 ) {
  
  				gltfScene.nodes = nodes;
  
  			}
  
  			serializeUserData( scene, gltfScene );
  
  		}
  
  		/**
  		 * Creates a THREE.Scene to hold a list of objects and parse it
  		 * @param  {Array} objects List of objects to process
  		 */
  		function processObjects( objects ) {
  
  			var scene = new THREE.Scene();
  			scene.name = 'AuxScene';
  
  			for ( var i = 0; i < objects.length; i ++ ) {
  
  				// We push directly to children instead of calling `add` to prevent
  				// modify the .parent and break its original scene and hierarchy
  				scene.children.push( objects[ i ] );
  
  			}
  
  			processScene( scene );
  
  		}
  
  		function processInput( input ) {
  
  			input = input instanceof Array ? input : [ input ];
  
  			var objectsWithoutScene = [];
  
  			for ( var i = 0; i < input.length; i ++ ) {
  
  				if ( input[ i ] instanceof THREE.Scene ) {
  
  					processScene( input[ i ] );
  
  				} else {
  
  					objectsWithoutScene.push( input[ i ] );
  
  				}
  
  			}
  
  			if ( objectsWithoutScene.length > 0 ) {
  
  				processObjects( objectsWithoutScene );
  
  			}
  
  			for ( var i = 0; i < skins.length; ++ i ) {
  
  				processSkin( skins[ i ] );
  
  			}
  
  			for ( var i = 0; i < options.animations.length; ++ i ) {
  
  				processAnimation( options.animations[ i ], input[ 0 ] );
  
  			}
  
  		}
  
  		processInput( input );
  
  		Promise.all( pending ).then( function () {
  
  			// Merge buffers.
  			var blob = new Blob( buffers, { type: 'application/octet-stream' } );
  
  			// Declare extensions.
  			var extensionsUsedList = Object.keys( extensionsUsed );
  			if ( extensionsUsedList.length > 0 ) outputJSON.extensionsUsed = extensionsUsedList;
  
  			// Update bytelength of the single buffer.
  			if ( outputJSON.buffers && outputJSON.buffers.length > 0 ) outputJSON.buffers[ 0 ].byteLength = blob.size;
  
  			if ( options.binary === true ) {
  
  				// https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#glb-file-format-specification
  
  				var GLB_HEADER_BYTES = 12;
  				var GLB_HEADER_MAGIC = 0x46546C67;
  				var GLB_VERSION = 2;
  
  				var GLB_CHUNK_PREFIX_BYTES = 8;
  				var GLB_CHUNK_TYPE_JSON = 0x4E4F534A;
  				var GLB_CHUNK_TYPE_BIN = 0x004E4942;
  
  				var reader = new window.FileReader();
  				reader.readAsArrayBuffer( blob );
  				reader.onloadend = function () {
  
  					// Binary chunk.
  					var binaryChunk = getPaddedArrayBuffer( reader.result );
  					var binaryChunkPrefix = new DataView( new ArrayBuffer( GLB_CHUNK_PREFIX_BYTES ) );
  					binaryChunkPrefix.setUint32( 0, binaryChunk.byteLength, true );
  					binaryChunkPrefix.setUint32( 4, GLB_CHUNK_TYPE_BIN, true );
  
  					// JSON chunk.
  					var jsonChunk = getPaddedArrayBuffer( stringToArrayBuffer( JSON.stringify( outputJSON ) ), 0x20 );
  					var jsonChunkPrefix = new DataView( new ArrayBuffer( GLB_CHUNK_PREFIX_BYTES ) );
  					jsonChunkPrefix.setUint32( 0, jsonChunk.byteLength, true );
  					jsonChunkPrefix.setUint32( 4, GLB_CHUNK_TYPE_JSON, true );
  
  					// GLB header.
  					var header = new ArrayBuffer( GLB_HEADER_BYTES );
  					var headerView = new DataView( header );
  					headerView.setUint32( 0, GLB_HEADER_MAGIC, true );
  					headerView.setUint32( 4, GLB_VERSION, true );
  					var totalByteLength = GLB_HEADER_BYTES
  						+ jsonChunkPrefix.byteLength + jsonChunk.byteLength
  						+ binaryChunkPrefix.byteLength + binaryChunk.byteLength;
  					headerView.setUint32( 8, totalByteLength, true );
  
  					var glbBlob = new Blob( [
  						header,
  						jsonChunkPrefix,
  						jsonChunk,
  						binaryChunkPrefix,
  						binaryChunk
  					], { type: 'application/octet-stream' } );
  
  					var glbReader = new window.FileReader();
  					glbReader.readAsArrayBuffer( glbBlob );
  					glbReader.onloadend = function () {
  
  						onDone( glbReader.result );
  
  					};
  
  				};
  
  			} else {
  
  				if ( outputJSON.buffers && outputJSON.buffers.length > 0 ) {
  
  					var reader = new window.FileReader();
  					reader.readAsDataURL( blob );
  					reader.onloadend = function () {
  
  						var base64data = reader.result;
  						outputJSON.buffers[ 0 ].uri = base64data;
  						onDone( outputJSON );
  
  					};
  
  				} else {
  
  					onDone( outputJSON );
  
  				}
  
  			}
  
  		} );
  
  	}
  
  };
  
  THREE.GLTFExporter.Utils = {
  
  	insertKeyframe: function ( track, time ) {
  
  		var tolerance = 0.001; // 1ms
  		var valueSize = track.getValueSize();
  
  		var times = new track.TimeBufferType( track.times.length + 1 );
  		var values = new track.ValueBufferType( track.values.length + valueSize );
  		var interpolant = track.createInterpolant( new track.ValueBufferType( valueSize ) );
  
  		var index;
  
  		if ( track.times.length === 0 ) {
  
  			times[ 0 ] = time;
  
  			for ( var i = 0; i < valueSize; i ++ ) {
  
  				values[ i ] = 0;
  
  			}
  
  			index = 0;
  
  		} else if ( time < track.times[ 0 ] ) {
  
  			if ( Math.abs( track.times[ 0 ] - time ) < tolerance ) return 0;
  
  			times[ 0 ] = time;
  			times.set( track.times, 1 );
  
  			values.set( interpolant.evaluate( time ), 0 );
  			values.set( track.values, valueSize );
  
  			index = 0;
  
  		} else if ( time > track.times[ track.times.length - 1 ] ) {
  
  			if ( Math.abs( track.times[ track.times.length - 1 ] - time ) < tolerance ) {
  
  				return track.times.length - 1;
  
  			}
  
  			times[ times.length - 1 ] = time;
  			times.set( track.times, 0 );
  
  			values.set( track.values, 0 );
  			values.set( interpolant.evaluate( time ), track.values.length );
  
  			index = times.length - 1;
  
  		} else {
  
  			for ( var i = 0; i < track.times.length; i ++ ) {
  
  				if ( Math.abs( track.times[ i ] - time ) < tolerance ) return i;
  
  				if ( track.times[ i ] < time && track.times[ i + 1 ] > time ) {
  
  					times.set( track.times.slice( 0, i + 1 ), 0 );
  					times[ i + 1 ] = time;
  					times.set( track.times.slice( i + 1 ), i + 2 );
  
  					values.set( track.values.slice( 0, ( i + 1 ) * valueSize ), 0 );
  					values.set( interpolant.evaluate( time ), ( i + 1 ) * valueSize );
  					values.set( track.values.slice( ( i + 1 ) * valueSize ), ( i + 2 ) * valueSize );
  
  					index = i + 1;
  
  					break;
  
  				}
  
  			}
  
  		}
  
  		track.times = times;
  		track.values = values;
  
  		return index;
  
  	},
  
  	mergeMorphTargetTracks: function ( clip, root ) {
  
  		var tracks = [];
  		var mergedTracks = {};
  		var sourceTracks = clip.tracks;
  
  		for ( var i = 0; i < sourceTracks.length; ++ i ) {
  
  			var sourceTrack = sourceTracks[ i ];
  			var sourceTrackBinding = THREE.PropertyBinding.parseTrackName( sourceTrack.name );
  			var sourceTrackNode = THREE.PropertyBinding.findNode( root, sourceTrackBinding.nodeName );
  
  			if ( sourceTrackBinding.propertyName !== 'morphTargetInfluences' || sourceTrackBinding.propertyIndex === undefined ) {
  
  				// Tracks that don't affect morph targets, or that affect all morph targets together, can be left as-is.
  				tracks.push( sourceTrack );
  				continue;
  
  			}
  
  			if ( sourceTrack.createInterpolant !== sourceTrack.InterpolantFactoryMethodDiscrete
  				&& sourceTrack.createInterpolant !== sourceTrack.InterpolantFactoryMethodLinear ) {
  
  				if ( sourceTrack.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline ) {
  
  					// This should never happen, because glTF morph target animations
  					// affect all targets already.
  					throw new Error( 'THREE.GLTFExporter: Cannot merge tracks with glTF CUBICSPLINE interpolation.' );
  
  				}
  
  				console.warn( 'THREE.GLTFExporter: Morph target interpolation mode not yet supported. Using LINEAR instead.' );
  
  				sourceTrack = sourceTrack.clone();
  				sourceTrack.setInterpolation( THREE.InterpolateLinear );
  
  			}
  
  			var targetCount = sourceTrackNode.morphTargetInfluences.length;
  			var targetIndex = sourceTrackNode.morphTargetDictionary[ sourceTrackBinding.propertyIndex ];
  
  			if ( targetIndex === undefined ) {
  
  				throw new Error( 'THREE.GLTFExporter: Morph target name not found: ' + sourceTrackBinding.propertyIndex );
  
  			}
  
  			var mergedTrack;
  
  			// If this is the first time we've seen this object, create a new
  			// track to store merged keyframe data for each morph target.
  			if ( mergedTracks[ sourceTrackNode.uuid ] === undefined ) {
  
  				mergedTrack = sourceTrack.clone();
  
  				var values = new mergedTrack.ValueBufferType( targetCount * mergedTrack.times.length );
  
  				for ( var j = 0; j < mergedTrack.times.length; j ++ ) {
  
  					values[ j * targetCount + targetIndex ] = mergedTrack.values[ j ];
  
  				}
  
  				// We need to take into consideration the intended target node
  				// of our original un-merged morphTarget animation.
  				mergedTrack.name = sourceTrackBinding.nodeName + '.morphTargetInfluences';
  				mergedTrack.values = values;
  
  				mergedTracks[ sourceTrackNode.uuid ] = mergedTrack;
  				tracks.push( mergedTrack );
  
  				continue;
  
  			}
  
  			var sourceInterpolant = sourceTrack.createInterpolant( new sourceTrack.ValueBufferType( 1 ) );
  
  			mergedTrack = mergedTracks[ sourceTrackNode.uuid ];
  
  			// For every existing keyframe of the merged track, write a (possibly
  			// interpolated) value from the source track.
  			for ( var j = 0; j < mergedTrack.times.length; j ++ ) {
  
  				mergedTrack.values[ j * targetCount + targetIndex ] = sourceInterpolant.evaluate( mergedTrack.times[ j ] );
  
  			}
  
  			// For every existing keyframe of the source track, write a (possibly
  			// new) keyframe to the merged track. Values from the previous loop may
  			// be written again, but keyframes are de-duplicated.
  			for ( var j = 0; j < sourceTrack.times.length; j ++ ) {
  
  				var keyframeIndex = this.insertKeyframe( mergedTrack, sourceTrack.times[ j ] );
  				mergedTrack.values[ keyframeIndex * targetCount + targetIndex ] = sourceTrack.values[ j ];
  
  			}
  
  		}
  
  		clip.tracks = tracks;
  
  		return clip;
  
  	}
  
  };
  