class Object3D extends EventDispatcher {

	constructor() {

		super();

		this.isObject3D = true;

		Object.defineProperty( this, 'id', { value: _object3DId ++ } );

		this.uuid = generateUUID();

		this.name = '';
		this.type = 'Object3D';

		this.parent = null;
		this.children = [];

		this.up = Object3D.DefaultUp.clone();

		const position = new Vector3();
		const rotation = new Euler();
		const quaternion = new Quaternion();
		const scale = new Vector3( 1, 1, 1 );

		function onRotationChange() {

			quaternion.setFromEuler( rotation, false );

		}

		function onQuaternionChange() {

			rotation.setFromQuaternion( quaternion, undefined, false );

		}

		rotation._onChange( onRotationChange );
		quaternion._onChange( onQuaternionChange );

		Object.defineProperties( this, {
			position: {
				configurable: true,
				enumerable: true,
				value: position
			},
			rotation: {
				configurable: true,
				enumerable: true,
				value: rotation
			},
			quaternion: {
				configurable: true,
				enumerable: true,
				value: quaternion
			},
			scale: {
				configurable: true,
				enumerable: true,
				value: scale
			},
			modelViewMatrix: {
				value: new Matrix4()
			},
			normalMatrix: {
				value: new Matrix3()
			}
		} );

		this.matrix = new Matrix4();
		this.matrixWorld = new Matrix4();

		this.matrixAutoUpdate = Object3D.DefaultMatrixAutoUpdate;
		this.matrixWorldNeedsUpdate = false;

		this.matrixWorldAutoUpdate = Object3D.DefaultMatrixWorldAutoUpdate; // checked by the renderer

		this.layers = new Layers();
		this.visible = true;
		this.choice = null;

		this.castShadow = false;
		this.receiveShadow = false;

		this.frustumCulled = true;
		this.renderOrder = 0;

		this.animations = [];

		this.userData = {};

	}

	onBeforeRender( /* renderer, scene, camera, geometry, material, group */ ) {}

	onAfterRender( /* renderer, scene, camera, geometry, material, group */ ) {}

	applyMatrix4( matrix ) {

		if ( this.matrixAutoUpdate ) this.updateMatrix();

		this.matrix.premultiply( matrix );

		this.matrix.decompose( this.position, this.quaternion, this.scale );

	}

	applyQuaternion( q ) {

		this.quaternion.premultiply( q );

		return this;

	}

	setRotationFromAxisAngle( axis, angle ) {

		// assumes axis is normalized

		this.quaternion.setFromAxisAngle( axis, angle );

	}

	setRotationFromEuler( euler ) {

		this.quaternion.setFromEuler( euler, true );

	}

	setRotationFromMatrix( m ) {

		// assumes the upper 3x3 of m is a pure rotation matrix (i.e, unscaled)

		this.quaternion.setFromRotationMatrix( m );

	}

	setRotationFromQuaternion( q ) {

		// assumes q is normalized

		this.quaternion.copy( q );

	}

	rotateOnAxis( axis, angle ) {

		// rotate object on axis in object space
		// axis is assumed to be normalized

		_q1.setFromAxisAngle( axis, angle );

		this.quaternion.multiply( _q1 );

		return this;

	}

	rotateOnWorldAxis( axis, angle ) {

		// rotate object on axis in world space
		// axis is assumed to be normalized
		// method assumes no rotated parent

		_q1.setFromAxisAngle( axis, angle );

		this.quaternion.premultiply( _q1 );

		return this;

	}

	rotateX( angle ) {

		return this.rotateOnAxis( _xAxis, angle );

	}

	rotateY( angle ) {

		return this.rotateOnAxis( _yAxis, angle );

	}

	rotateZ( angle ) {

		return this.rotateOnAxis( _zAxis, angle );

	}

	translateOnAxis( axis, distance ) {

		// translate object by distance along axis in object space
		// axis is assumed to be normalized

		_v1$4.copy( axis ).applyQuaternion( this.quaternion );

		this.position.add( _v1$4.multiplyScalar( distance ) );

		return this;

	}

	translateX( distance ) {

		return this.translateOnAxis( _xAxis, distance );

	}

	translateY( distance ) {

		return this.translateOnAxis( _yAxis, distance );

	}

	translateZ( distance ) {

		return this.translateOnAxis( _zAxis, distance );

	}

	localToWorld( vector ) {

		return vector.applyMatrix4( this.matrixWorld );

	}

	worldToLocal( vector ) {

		return vector.applyMatrix4( _m1$1.copy( this.matrixWorld ).invert() );

	}

	lookAt( x, y, z ) {

		// This method does not support objects having non-uniformly-scaled parent(s)

		if ( x.isVector3 ) {

			_target.copy( x );

		} else {

			_target.set( x, y, z );

		}

		const parent = this.parent;

		this.updateWorldMatrix( true, false );

		_position$3.setFromMatrixPosition( this.matrixWorld );

		if ( this.isCamera || this.isLight ) {

			_m1$1.lookAt( _position$3, _target, this.up );

		} else {

			_m1$1.lookAt( _target, _position$3, this.up );

		}

		this.quaternion.setFromRotationMatrix( _m1$1 );

		if ( parent ) {

			_m1$1.extractRotation( parent.matrixWorld );
			_q1.setFromRotationMatrix( _m1$1 );
			this.quaternion.premultiply( _q1.invert() );

		}

	}

	add( object ) {

		if ( arguments.length > 1 ) {

			for ( let i = 0; i < arguments.length; i ++ ) {

				this.add( arguments[ i ] );

			}

			return this;

		}

		if ( object === this ) {

			console.error( 'THREE.Object3D.add: object can\'t be added as a child of itself.', object );
			return this;

		}

		if ( object && object.isObject3D ) {

			if ( object.parent !== null ) {

				object.parent.remove( object );

			}

			object.parent = this;
			this.children.push( object );

			object.dispatchEvent( _addedEvent );

		} else {

			console.error( 'THREE.Object3D.add: object not an instance of THREE.Object3D.', object );

		}

		return this;

	}

	remove( object ) {

		if ( arguments.length > 1 ) {

			for ( let i = 0; i < arguments.length; i ++ ) {

				this.remove( arguments[ i ] );

			}

			return this;

		}

		const index = this.children.indexOf( object );

		if ( index !== - 1 ) {

			object.parent = null;
			this.children.splice( index, 1 );

			object.dispatchEvent( _removedEvent );

		}

		return this;

	}

	removeFromParent() {

		const parent = this.parent;

		if ( parent !== null ) {

			parent.remove( this );

		}

		return this;

	}

	clear() {

		for ( let i = 0; i < this.children.length; i ++ ) {

			const object = this.children[ i ];

			object.parent = null;

			object.dispatchEvent( _removedEvent );

		}

		this.children.length = 0;

		return this;


	}

	attach( object ) {

		// adds object as a child of this, while maintaining the object's world transform

		// Note: This method does not support scene graphs having non-uniformly-scaled nodes(s)

		this.updateWorldMatrix( true, false );

		_m1$1.copy( this.matrixWorld ).invert();

		if ( object.parent !== null ) {

			object.parent.updateWorldMatrix( true, false );

			_m1$1.multiply( object.parent.matrixWorld );

		}

		object.applyMatrix4( _m1$1 );

		this.add( object );

		object.updateWorldMatrix( false, true );

		return this;

	}

	getObjectById( id ) {

		return this.getObjectByProperty( 'id', id );

	}

	getObjectByName( name ) {

		return this.getObjectByProperty( 'name', name );

	}

	getObjectByProperty( name, value ) {

		if ( this[ name ] === value ) return this;

		for ( let i = 0, l = this.children.length; i < l; i ++ ) {

			const child = this.children[ i ];
			const object = child.getObjectByProperty( name, value );

			if ( object !== undefined ) {

				return object;

			}

		}

		return undefined;

	}

	getWorldPosition( target ) {

		this.updateWorldMatrix( true, false );

		return target.setFromMatrixPosition( this.matrixWorld );

	}

	getWorldQuaternion( target ) {

		this.updateWorldMatrix( true, false );

		this.matrixWorld.decompose( _position$3, target, _scale$2 );

		return target;

	}

	getWorldScale( target ) {

		this.updateWorldMatrix( true, false );

		this.matrixWorld.decompose( _position$3, _quaternion$2, target );

		return target;

	}

	getWorldDirection( target ) {

		this.updateWorldMatrix( true, false );

		const e = this.matrixWorld.elements;

		return target.set( e[ 8 ], e[ 9 ], e[ 10 ] ).normalize();

	}

	raycast( /* raycaster, intersects */ ) {}

	traverse( callback ) {

		callback( this );

		const children = this.children;

		for ( let i = 0, l = children.length; i < l; i ++ ) {

			children[ i ].traverse( callback );

		}

	}

	traverseVisible( callback ) {

		if ( this.visible === false ) return;

		callback( this );

		const children = this.children;

		for ( let i = 0, l = children.length; i < l; i ++ ) {

			children[ i ].traverseVisible( callback );

		}

	}

	traverseAncestors( callback ) {

		const parent = this.parent;

		if ( parent !== null ) {

			callback( parent );

			parent.traverseAncestors( callback );

		}

	}

	updateMatrix() {

		this.matrix.compose( this.position, this.quaternion, this.scale );

		this.matrixWorldNeedsUpdate = true;

	}

	updateMatrixWorld( force ) {

		if ( this.matrixAutoUpdate ) this.updateMatrix();

		if ( this.matrixWorldNeedsUpdate || force ) {

			if ( this.parent === null ) {

				this.matrixWorld.copy( this.matrix );

			} else {

				this.matrixWorld.multiplyMatrices( this.parent.matrixWorld, this.matrix );

			}

			this.matrixWorldNeedsUpdate = false;

			force = true;

		}

		// update children

		const children = this.children;

		for ( let i = 0, l = children.length; i < l; i ++ ) {

			const child = children[ i ];

			if ( child.matrixWorldAutoUpdate === true || force === true ) {

				child.updateMatrixWorld( force );

			}

		}

	}

	updateWorldMatrix( updateParents, updateChildren ) {

		const parent = this.parent;

		if ( updateParents === true && parent !== null && parent.matrixWorldAutoUpdate === true ) {

			parent.updateWorldMatrix( true, false );

		}

		if ( this.matrixAutoUpdate ) this.updateMatrix();

		if ( this.parent === null ) {

			this.matrixWorld.copy( this.matrix );

		} else {

			this.matrixWorld.multiplyMatrices( this.parent.matrixWorld, this.matrix );

		}

		// update children

		if ( updateChildren === true ) {

			const children = this.children;

			for ( let i = 0, l = children.length; i < l; i ++ ) {

				const child = children[ i ];

				if ( child.matrixWorldAutoUpdate === true ) {

					child.updateWorldMatrix( false, true );

				}

			}

		}

	}

	toJSON( meta ) {

		// meta is a string when called from JSON.stringify
		const isRootObject = ( meta === undefined || typeof meta === 'string' );

		const output = {};

		// meta is a hash used to collect geometries, materials.
		// not providing it implies that this is the root object
		// being serialized.
		if ( isRootObject ) {

			// initialize meta obj
			meta = {
				geometries: {},
				materials: {},
				textures: {},
				images: {},
				shapes: {},
				skeletons: {},
				animations: {},
				nodes: {}
			};

			output.metadata = {
				version: 4.5,
				type: 'Object',
				generator: 'Object3D.toJSON'
			};

		}

		// standard Object3D serialization

		const object = {};

		object.uuid = this.uuid;
		object.type = this.type;
		object.choice = this.choice;

		if ( this.name !== '' ) object.name = this.name;
		if ( this.castShadow === true ) object.castShadow = true;
		if ( this.receiveShadow === true ) object.receiveShadow = true;
		if ( this.visible === false ) object.visible = false;
		// if ( this.choice === false ) object.choice = false;
		if ( this.frustumCulled === false ) object.frustumCulled = false;
		if ( this.renderOrder !== 0 ) object.renderOrder = this.renderOrder;
		if ( JSON.stringify( this.userData ) !== '{}' ) object.userData = this.userData;

		object.layers = this.layers.mask;
		object.matrix = this.matrix.toArray();

		if ( this.matrixAutoUpdate === false ) object.matrixAutoUpdate = false;

		// object specific properties

		if ( this.isInstancedMesh ) {

			object.type = 'InstancedMesh';
			object.count = this.count;
			object.instanceMatrix = this.instanceMatrix.toJSON();
			if ( this.instanceColor !== null ) object.instanceColor = this.instanceColor.toJSON();

		}

		//

		function serialize( library, element ) {

			if ( library[ element.uuid ] === undefined ) {

				library[ element.uuid ] = element.toJSON( meta );

			}

			return element.uuid;

		}

		if ( this.isScene ) {

			if ( this.background ) {

				if ( this.background.isColor ) {

					object.background = this.background.toJSON();

				} else if ( this.background.isTexture ) {

					object.background = this.background.toJSON( meta ).uuid;

				}

			}

			if ( this.environment && this.environment.isTexture && this.environment.isRenderTargetTexture !== true ) {

				object.environment = this.environment.toJSON( meta ).uuid;

			}

		} else if ( this.isMesh || this.isLine || this.isPoints ) {

			object.geometry = serialize( meta.geometries, this.geometry );

			const parameters = this.geometry.parameters;

			if ( parameters !== undefined && parameters.shapes !== undefined ) {

				const shapes = parameters.shapes;

				if ( Array.isArray( shapes ) ) {

					for ( let i = 0, l = shapes.length; i < l; i ++ ) {

						const shape = shapes[ i ];

						serialize( meta.shapes, shape );

					}

				} else {

					serialize( meta.shapes, shapes );

				}

			}

		}

		if ( this.isSkinnedMesh ) {

			object.bindMode = this.bindMode;
			object.bindMatrix = this.bindMatrix.toArray();

			if ( this.skeleton !== undefined ) {

				serialize( meta.skeletons, this.skeleton );

				object.skeleton = this.skeleton.uuid;

			}

		}

		if ( this.material !== undefined ) {

			if ( Array.isArray( this.material ) ) {

				const uuids = [];

				for ( let i = 0, l = this.material.length; i < l; i ++ ) {

					uuids.push( serialize( meta.materials, this.material[ i ] ) );

				}

				object.material = uuids;

			} else {

				object.material = serialize( meta.materials, this.material );

			}

		}

		//

		if ( this.children.length > 0 ) {

			object.children = [];

			for ( let i = 0; i < this.children.length; i ++ ) {

				object.children.push( this.children[ i ].toJSON( meta ).object );

			}

		}

		//

		if ( this.animations.length > 0 ) {

			object.animations = [];

			for ( let i = 0; i < this.animations.length; i ++ ) {

				const animation = this.animations[ i ];

				object.animations.push( serialize( meta.animations, animation ) );

			}

		}

		if ( isRootObject ) {

			const geometries = extractFromCache( meta.geometries );
			const materials = extractFromCache( meta.materials );
			const textures = extractFromCache( meta.textures );
			const images = extractFromCache( meta.images );
			const shapes = extractFromCache( meta.shapes );
			const skeletons = extractFromCache( meta.skeletons );
			const animations = extractFromCache( meta.animations );
			const nodes = extractFromCache( meta.nodes );

			if ( geometries.length > 0 ) output.geometries = geometries;
			if ( materials.length > 0 ) output.materials = materials;
			if ( textures.length > 0 ) output.textures = textures;
			if ( images.length > 0 ) output.images = images;
			if ( shapes.length > 0 ) output.shapes = shapes;
			if ( skeletons.length > 0 ) output.skeletons = skeletons;
			if ( animations.length > 0 ) output.animations = animations;
			if ( nodes.length > 0 ) output.nodes = nodes;

		}

		output.object = object;

		return output;

		// extract data from the cache hash
		// remove metadata on each item
		// and return as array
		function extractFromCache( cache ) {

			const values = [];
			for ( const key in cache ) {

				const data = cache[ key ];
				delete data.metadata;
				values.push( data );

			}

			return values;

		}

	}

	clone( recursive ) {

		return new this.constructor().copy( this, recursive );

	}

	copy( source, recursive = true ) {

		this.name = source.name;

		this.up.copy( source.up );

		this.position.copy( source.position );
		this.rotation.order = source.rotation.order;
		this.quaternion.copy( source.quaternion );
		this.scale.copy( source.scale );

		this.matrix.copy( source.matrix );
		this.matrixWorld.copy( source.matrixWorld );

		this.matrixAutoUpdate = source.matrixAutoUpdate;
		this.matrixWorldNeedsUpdate = source.matrixWorldNeedsUpdate;

		this.matrixWorldAutoUpdate = source.matrixWorldAutoUpdate;

		this.layers.mask = source.layers.mask;
		this.visible = source.visible;
		this.choice = source.choice;

		this.castShadow = source.castShadow;
		this.receiveShadow = source.receiveShadow;

		this.frustumCulled = source.frustumCulled;
		this.renderOrder = source.renderOrder;

		this.userData = JSON.parse( JSON.stringify( source.userData ) );

		if ( recursive === true ) {

			for ( let i = 0; i < source.children.length; i ++ ) {

				const child = source.children[ i ];
				this.add( child.clone() );

			}

		}

		return this;

	}

}