3d-force-graph.js

  		if ( _keyState !== STATE.NONE ) {

  			return;

  		} else if ( event.keyCode === scope.keys[ STATE.ROTATE ] && ! scope.noRotate ) {

  			_keyState = STATE.ROTATE;

  		} else if ( event.keyCode === scope.keys[ STATE.ZOOM ] && ! scope.noZoom ) {

  			_keyState = STATE.ZOOM;

  		} else if ( event.keyCode === scope.keys[ STATE.PAN ] && ! scope.noPan ) {

  			_keyState = STATE.PAN;

  		}

  	}

  	function keyup() {

  		if ( scope.enabled === false ) return;

  		_keyState = STATE.NONE;

  		window.addEventListener( 'keydown', keydown, false );

  	}

  	function mousedown( event ) {

  		if ( scope.enabled === false ) return;

  		event.preventDefault();
  		event.stopPropagation();

  		if ( _state === STATE.NONE ) {

  			switch ( event.button ) {

  				case scope.mouseButtons.LEFT:
  					_state = STATE.ROTATE;
  					break;

  				case scope.mouseButtons.MIDDLE:
  					_state = STATE.ZOOM;
  					break;

  				case scope.mouseButtons.RIGHT:
  					_state = STATE.PAN;
  					break;

  				default:
  					_state = STATE.NONE;

  			}

  		}

  		var state = ( _keyState !== STATE.NONE ) ? _keyState : _state;

  		if ( state === STATE.ROTATE && ! scope.noRotate ) {

  			_moveCurr.copy( getMouseOnCircle( event.pageX, event.pageY ) );
  			_movePrev.copy( _moveCurr );

  		} else if ( state === STATE.ZOOM && ! scope.noZoom ) {

  			_zoomStart.copy( getMouseOnScreen( event.pageX, event.pageY ) );
  			_zoomEnd.copy( _zoomStart );

  		} else if ( state === STATE.PAN && ! scope.noPan ) {

  			_panStart.copy( getMouseOnScreen( event.pageX, event.pageY ) );
  			_panEnd.copy( _panStart );

  		}

  		scope.domElement.ownerDocument.addEventListener( 'mousemove', mousemove, false );
  		scope.domElement.ownerDocument.addEventListener( 'mouseup', mouseup, false );

  		scope.dispatchEvent( startEvent );

  	}

  	function mousemove( event ) {

  		if ( scope.enabled === false ) return;

  		event.preventDefault();
  		event.stopPropagation();

  		var state = ( _keyState !== STATE.NONE ) ? _keyState : _state;

  		if ( state === STATE.ROTATE && ! scope.noRotate ) {

  			_movePrev.copy( _moveCurr );
  			_moveCurr.copy( getMouseOnCircle( event.pageX, event.pageY ) );

  		} else if ( state === STATE.ZOOM && ! scope.noZoom ) {

  			_zoomEnd.copy( getMouseOnScreen( event.pageX, event.pageY ) );

  		} else if ( state === STATE.PAN && ! scope.noPan ) {

  			_panEnd.copy( getMouseOnScreen( event.pageX, event.pageY ) );

  		}

  	}

  	function mouseup( event ) {

  		if ( scope.enabled === false ) return;

  		event.preventDefault();
  		event.stopPropagation();

  		_state = STATE.NONE;

  		scope.domElement.ownerDocument.removeEventListener( 'mousemove', mousemove );
  		scope.domElement.ownerDocument.removeEventListener( 'mouseup', mouseup );
  		scope.dispatchEvent( endEvent );

  	}

  	function mousewheel( event ) {

  		if ( scope.enabled === false ) return;

  		if ( scope.noZoom === true ) return;

  		event.preventDefault();
  		event.stopPropagation();

  		switch ( event.deltaMode ) {

  			case 2:
  				// Zoom in pages
  				_zoomStart.y -= event.deltaY * 0.025;
  				break;

  			case 1:
  				// Zoom in lines
  				_zoomStart.y -= event.deltaY * 0.01;
  				break;

  			default:
  				// undefined, 0, assume pixels
  				_zoomStart.y -= event.deltaY * 0.00025;
  				break;

  		}

  		scope.dispatchEvent( startEvent );
  		scope.dispatchEvent( endEvent );

  	}

  	function touchstart( event ) {

  		if ( scope.enabled === false ) return;

  		event.preventDefault();

  		switch ( event.touches.length ) {

  			case 1:
  				_state = STATE.TOUCH_ROTATE;
  				_moveCurr.copy( getMouseOnCircle( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
  				_movePrev.copy( _moveCurr );
  				break;

  			default: // 2 or more
  				_state = STATE.TOUCH_ZOOM_PAN;
  				var dx = event.touches[ 0 ].pageX - event.touches[ 1 ].pageX;
  				var dy = event.touches[ 0 ].pageY - event.touches[ 1 ].pageY;
  				_touchZoomDistanceEnd = _touchZoomDistanceStart = Math.sqrt( dx * dx + dy * dy );

  				var x = ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX ) / 2;
  				var y = ( event.touches[ 0 ].pageY + event.touches[ 1 ].pageY ) / 2;
  				_panStart.copy( getMouseOnScreen( x, y ) );
  				_panEnd.copy( _panStart );
  				break;

  		}

  		scope.dispatchEvent( startEvent );

  	}

  	function touchmove( event ) {

  		if ( scope.enabled === false ) return;

  		event.preventDefault();
  		event.stopPropagation();

  		switch ( event.touches.length ) {

  			case 1:
  				_movePrev.copy( _moveCurr );
  				_moveCurr.copy( getMouseOnCircle( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
  				break;

  			default: // 2 or more
  				var dx = event.touches[ 0 ].pageX - event.touches[ 1 ].pageX;
  				var dy = event.touches[ 0 ].pageY - event.touches[ 1 ].pageY;
  				_touchZoomDistanceEnd = Math.sqrt( dx * dx + dy * dy );

  				var x = ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX ) / 2;
  				var y = ( event.touches[ 0 ].pageY + event.touches[ 1 ].pageY ) / 2;
  				_panEnd.copy( getMouseOnScreen( x, y ) );
  				break;

  		}

  	}

  	function touchend( event ) {

  		if ( scope.enabled === false ) return;

  		switch ( event.touches.length ) {

  			case 0:
  				_state = STATE.NONE;
  				break;

  			case 1:
  				_state = STATE.TOUCH_ROTATE;
  				_moveCurr.copy( getMouseOnCircle( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY ) );
  				_movePrev.copy( _moveCurr );
  				break;

  		}

  		scope.dispatchEvent( endEvent );

  	}

  	function contextmenu( event ) {

  		if ( scope.enabled === false ) return;

  		event.preventDefault();

  	}

  	this.dispose = function () {

  		scope.domElement.removeEventListener( 'contextmenu', contextmenu, false );
  		scope.domElement.removeEventListener( 'mousedown', mousedown, false );
  		scope.domElement.removeEventListener( 'wheel', mousewheel, false );

  		scope.domElement.removeEventListener( 'touchstart', touchstart, false );
  		scope.domElement.removeEventListener( 'touchend', touchend, false );
  		scope.domElement.removeEventListener( 'touchmove', touchmove, false );

  		scope.domElement.ownerDocument.removeEventListener( 'mousemove', mousemove, false );
  		scope.domElement.ownerDocument.removeEventListener( 'mouseup', mouseup, false );

  		window.removeEventListener( 'keydown', keydown, false );
  		window.removeEventListener( 'keyup', keyup, false );

  	};

  	this.domElement.addEventListener( 'contextmenu', contextmenu, false );
  	this.domElement.addEventListener( 'mousedown', mousedown, false );
  	this.domElement.addEventListener( 'wheel', mousewheel, false );

  	this.domElement.addEventListener( 'touchstart', touchstart, false );
  	this.domElement.addEventListener( 'touchend', touchend, false );
  	this.domElement.addEventListener( 'touchmove', touchmove, false );

  	window.addEventListener( 'keydown', keydown, false );
  	window.addEventListener( 'keyup', keyup, false );

  	this.handleResize();

  	// force an update at start
  	this.update();

  };

  TrackballControls.prototype = Object.create( EventDispatcher.prototype );
  TrackballControls.prototype.constructor = TrackballControls;

  /**
   * @author qiao / https://github.com/qiao
   * @author mrdoob / http://mrdoob.com
   * @author alteredq / http://alteredqualia.com/
   * @author WestLangley / http://github.com/WestLangley
   * @author erich666 / http://erichaines.com
   * @author ScieCode / http://github.com/sciecode
   */

  // This set of controls performs orbiting, dollying (zooming), and panning.
  // Unlike TrackballControls, it maintains the "up" direction object.up (+Y by default).
  //
  //    Orbit - left mouse / touch: one-finger move
  //    Zoom - middle mouse, or mousewheel / touch: two-finger spread or squish
  //    Pan - right mouse, or left mouse + ctrl/meta/shiftKey, or arrow keys / touch: two-finger move

  var OrbitControls = function ( object, domElement ) {

  	if ( domElement === undefined ) console.warn( 'THREE.OrbitControls: The second parameter "domElement" is now mandatory.' );
  	if ( domElement === document ) console.error( 'THREE.OrbitControls: "document" should not be used as the target "domElement". Please use "renderer.domElement" instead.' );

  	this.object = object;
  	this.domElement = domElement;

  	// Set to false to disable this control
  	this.enabled = true;

  	// "target" sets the location of focus, where the object orbits around
  	this.target = new Vector3();

  	// How far you can dolly in and out ( PerspectiveCamera only )
  	this.minDistance = 0;
  	this.maxDistance = Infinity;

  	// How far you can zoom in and out ( OrthographicCamera only )
  	this.minZoom = 0;
  	this.maxZoom = Infinity;

  	// How far you can orbit vertically, upper and lower limits.
  	// Range is 0 to Math.PI radians.
  	this.minPolarAngle = 0; // radians
  	this.maxPolarAngle = Math.PI; // radians

  	// How far you can orbit horizontally, upper and lower limits.
  	// If set, the interval [ min, max ] must be a sub-interval of [ - 2 PI, 2 PI ], with ( max - min < 2 PI )
  	this.minAzimuthAngle = - Infinity; // radians
  	this.maxAzimuthAngle = Infinity; // radians

  	// Set to true to enable damping (inertia)
  	// If damping is enabled, you must call controls.update() in your animation loop
  	this.enableDamping = false;
  	this.dampingFactor = 0.05;

  	// This option actually enables dollying in and out; left as "zoom" for backwards compatibility.
  	// Set to false to disable zooming
  	this.enableZoom = true;
  	this.zoomSpeed = 1.0;

  	// Set to false to disable rotating
  	this.enableRotate = true;
  	this.rotateSpeed = 1.0;

  	// Set to false to disable panning
  	this.enablePan = true;
  	this.panSpeed = 1.0;
  	this.screenSpacePanning = true; // if false, pan orthogonal to world-space direction camera.up
  	this.keyPanSpeed = 7.0;	// pixels moved per arrow key push

  	// Set to true to automatically rotate around the target
  	// If auto-rotate is enabled, you must call controls.update() in your animation loop
  	this.autoRotate = false;
  	this.autoRotateSpeed = 2.0; // 30 seconds per round when fps is 60

  	// Set to false to disable use of the keys
  	this.enableKeys = true;

  	// The four arrow keys
  	this.keys = { LEFT: 37, UP: 38, RIGHT: 39, BOTTOM: 40 };

  	// Mouse buttons
  	this.mouseButtons = { LEFT: MOUSE.ROTATE, MIDDLE: MOUSE.DOLLY, RIGHT: MOUSE.PAN };

  	// Touch fingers
  	this.touches = { ONE: TOUCH.ROTATE, TWO: TOUCH.DOLLY_PAN };

  	// for reset
  	this.target0 = this.target.clone();
  	this.position0 = this.object.position.clone();
  	this.zoom0 = this.object.zoom;

  	//
  	// public methods
  	//

  	this.getPolarAngle = function () {

  		return spherical.phi;

  	};

  	this.getAzimuthalAngle = function () {

  		return spherical.theta;

  	};

  	this.saveState = function () {

  		scope.target0.copy( scope.target );
  		scope.position0.copy( scope.object.position );
  		scope.zoom0 = scope.object.zoom;

  	};

  	this.reset = function () {

  		scope.target.copy( scope.target0 );
  		scope.object.position.copy( scope.position0 );
  		scope.object.zoom = scope.zoom0;

  		scope.object.updateProjectionMatrix();
  		scope.dispatchEvent( changeEvent );

  		scope.update();

  		state = STATE.NONE;

  	};

  	// this method is exposed, but perhaps it would be better if we can make it private...
  	this.update = function () {

  		var offset = new Vector3();

  		// so camera.up is the orbit axis
  		var quat = new Quaternion().setFromUnitVectors( object.up, new Vector3( 0, 1, 0 ) );
  		var quatInverse = quat.clone().inverse();

  		var lastPosition = new Vector3();
  		var lastQuaternion = new Quaternion();

  		var twoPI = 2 * Math.PI;

  		return function update() {

  			var position = scope.object.position;

  			offset.copy( position ).sub( scope.target );

  			// rotate offset to "y-axis-is-up" space
  			offset.applyQuaternion( quat );

  			// angle from z-axis around y-axis
  			spherical.setFromVector3( offset );

  			if ( scope.autoRotate && state === STATE.NONE ) {

  				rotateLeft( getAutoRotationAngle() );

  			}

  			if ( scope.enableDamping ) {

  				spherical.theta += sphericalDelta.theta * scope.dampingFactor;
  				spherical.phi += sphericalDelta.phi * scope.dampingFactor;

  			} else {

  				spherical.theta += sphericalDelta.theta;
  				spherical.phi += sphericalDelta.phi;

  			}

  			// restrict theta to be between desired limits

  			var min = scope.minAzimuthAngle;
  			var max = scope.maxAzimuthAngle;

  			if ( isFinite ( min ) && isFinite( max ) ) {

  				if ( min < - Math.PI ) min += twoPI; else if ( min > Math.PI ) min -= twoPI;

  				if ( max < - Math.PI ) max += twoPI; else if ( max > Math.PI ) max -= twoPI;

  				if ( min < max ) {

  					spherical.theta = Math.max( min, Math.min( max, spherical.theta ) );

  				} else {

  					spherical.theta = ( spherical.theta > ( min + max ) / 2 ) ?
  						Math.max( min, spherical.theta ) :
  						Math.min( max, spherical.theta );

  				}

  			}

  			// restrict phi to be between desired limits
  			spherical.phi = Math.max( scope.minPolarAngle, Math.min( scope.maxPolarAngle, spherical.phi ) );

  			spherical.makeSafe();


  			spherical.radius *= scale;

  			// restrict radius to be between desired limits
  			spherical.radius = Math.max( scope.minDistance, Math.min( scope.maxDistance, spherical.radius ) );

  			// move target to panned location

  			if ( scope.enableDamping === true ) {

  				scope.target.addScaledVector( panOffset, scope.dampingFactor );

  			} else {

  				scope.target.add( panOffset );

  			}

  			offset.setFromSpherical( spherical );

  			// rotate offset back to "camera-up-vector-is-up" space
  			offset.applyQuaternion( quatInverse );

  			position.copy( scope.target ).add( offset );

  			scope.object.lookAt( scope.target );

  			if ( scope.enableDamping === true ) {

  				sphericalDelta.theta *= ( 1 - scope.dampingFactor );
  				sphericalDelta.phi *= ( 1 - scope.dampingFactor );

  				panOffset.multiplyScalar( 1 - scope.dampingFactor );

  			} else {

  				sphericalDelta.set( 0, 0, 0 );

  				panOffset.set( 0, 0, 0 );

  			}

  			scale = 1;

  			// update condition is:
  			// min(camera displacement, camera rotation in radians)^2 > EPS
  			// using small-angle approximation cos(x/2) = 1 - x^2 / 8

  			if ( zoomChanged ||
  				lastPosition.distanceToSquared( scope.object.position ) > EPS ||
  				8 * ( 1 - lastQuaternion.dot( scope.object.quaternion ) ) > EPS ) {

  				scope.dispatchEvent( changeEvent );

  				lastPosition.copy( scope.object.position );
  				lastQuaternion.copy( scope.object.quaternion );
  				zoomChanged = false;

  				return true;

  			}

  			return false;

  		};

  	}();

  	this.dispose = function () {

  		scope.domElement.removeEventListener( 'contextmenu', onContextMenu, false );
  		scope.domElement.removeEventListener( 'mousedown', onMouseDown, false );
  		scope.domElement.removeEventListener( 'wheel', onMouseWheel, false );

  		scope.domElement.removeEventListener( 'touchstart', onTouchStart, false );
  		scope.domElement.removeEventListener( 'touchend', onTouchEnd, false );
  		scope.domElement.removeEventListener( 'touchmove', onTouchMove, false );

  		scope.domElement.ownerDocument.removeEventListener( 'mousemove', onMouseMove, false );
  		scope.domElement.ownerDocument.removeEventListener( 'mouseup', onMouseUp, false );

  		scope.domElement.removeEventListener( 'keydown', onKeyDown, false );

  		//scope.dispatchEvent( { type: 'dispose' } ); // should this be added here?

  	};

  	//
  	// internals
  	//

  	var scope = this;

  	var changeEvent = { type: 'change' };
  	var startEvent = { type: 'start' };
  	var endEvent = { type: 'end' };

  	var STATE = {
  		NONE: - 1,
  		ROTATE: 0,
  		DOLLY: 1,
  		PAN: 2,
  		TOUCH_ROTATE: 3,
  		TOUCH_PAN: 4,
  		TOUCH_DOLLY_PAN: 5,
  		TOUCH_DOLLY_ROTATE: 6
  	};

  	var state = STATE.NONE;

  	var EPS = 0.000001;

  	// current position in spherical coordinates
  	var spherical = new Spherical();
  	var sphericalDelta = new Spherical();

  	var scale = 1;
  	var panOffset = new Vector3();
  	var zoomChanged = false;

  	var rotateStart = new Vector2();
  	var rotateEnd = new Vector2();
  	var rotateDelta = new Vector2();

  	var panStart = new Vector2();
  	var panEnd = new Vector2();
  	var panDelta = new Vector2();

  	var dollyStart = new Vector2();
  	var dollyEnd = new Vector2();
  	var dollyDelta = new Vector2();

  	function getAutoRotationAngle() {

  		return 2 * Math.PI / 60 / 60 * scope.autoRotateSpeed;

  	}

  	function getZoomScale() {

  		return Math.pow( 0.95, scope.zoomSpeed );

  	}

  	function rotateLeft( angle ) {

  		sphericalDelta.theta -= angle;

  	}

  	function rotateUp( angle ) {

  		sphericalDelta.phi -= angle;

  	}

  	var panLeft = function () {

  		var v = new Vector3();

  		return function panLeft( distance, objectMatrix ) {

  			v.setFromMatrixColumn( objectMatrix, 0 ); // get X column of objectMatrix
  			v.multiplyScalar( - distance );

  			panOffset.add( v );

  		};

  	}();

  	var panUp = function () {

  		var v = new Vector3();

  		return function panUp( distance, objectMatrix ) {

  			if ( scope.screenSpacePanning === true ) {

  				v.setFromMatrixColumn( objectMatrix, 1 );

  			} else {

  				v.setFromMatrixColumn( objectMatrix, 0 );
  				v.crossVectors( scope.object.up, v );

  			}

  			v.multiplyScalar( distance );

  			panOffset.add( v );

  		};

  	}();

  	// deltaX and deltaY are in pixels; right and down are positive
  	var pan = function () {

  		var offset = new Vector3();

  		return function pan( deltaX, deltaY ) {

  			var element = scope.domElement;

  			if ( scope.object.isPerspectiveCamera ) {

  				// perspective
  				var position = scope.object.position;
  				offset.copy( position ).sub( scope.target );
  				var targetDistance = offset.length();

  				// half of the fov is center to top of screen
  				targetDistance *= Math.tan( ( scope.object.fov / 2 ) * Math.PI / 180.0 );

  				// we use only clientHeight here so aspect ratio does not distort speed
  				panLeft( 2 * deltaX * targetDistance / element.clientHeight, scope.object.matrix );
  				panUp( 2 * deltaY * targetDistance / element.clientHeight, scope.object.matrix );

  			} else if ( scope.object.isOrthographicCamera ) {

  				// orthographic
  				panLeft( deltaX * ( scope.object.right - scope.object.left ) / scope.object.zoom / element.clientWidth, scope.object.matrix );
  				panUp( deltaY * ( scope.object.top - scope.object.bottom ) / scope.object.zoom / element.clientHeight, scope.object.matrix );

  			} else {

  				// camera neither orthographic nor perspective
  				console.warn( 'WARNING: OrbitControls.js encountered an unknown camera type - pan disabled.' );
  				scope.enablePan = false;

  			}

  		};

  	}();

  	function dollyOut( dollyScale ) {

  		if ( scope.object.isPerspectiveCamera ) {

  			scale /= dollyScale;

  		} else if ( scope.object.isOrthographicCamera ) {

  			scope.object.zoom = Math.max( scope.minZoom, Math.min( scope.maxZoom, scope.object.zoom * dollyScale ) );
  			scope.object.updateProjectionMatrix();
  			zoomChanged = true;

  		} else {

  			console.warn( 'WARNING: OrbitControls.js encountered an unknown camera type - dolly/zoom disabled.' );
  			scope.enableZoom = false;

  		}

  	}

  	function dollyIn( dollyScale ) {

  		if ( scope.object.isPerspectiveCamera ) {

  			scale *= dollyScale;

  		} else if ( scope.object.isOrthographicCamera ) {

  			scope.object.zoom = Math.max( scope.minZoom, Math.min( scope.maxZoom, scope.object.zoom / dollyScale ) );
  			scope.object.updateProjectionMatrix();
  			zoomChanged = true;

  		} else {

  			console.warn( 'WARNING: OrbitControls.js encountered an unknown camera type - dolly/zoom disabled.' );
  			scope.enableZoom = false;

  		}

  	}

  	//
  	// event callbacks - update the object state
  	//

  	function handleMouseDownRotate( event ) {

  		rotateStart.set( event.clientX, event.clientY );

  	}

  	function handleMouseDownDolly( event ) {

  		dollyStart.set( event.clientX, event.clientY );

  	}

  	function handleMouseDownPan( event ) {

  		panStart.set( event.clientX, event.clientY );

  	}

  	function handleMouseMoveRotate( event ) {

  		rotateEnd.set( event.clientX, event.clientY );

  		rotateDelta.subVectors( rotateEnd, rotateStart ).multiplyScalar( scope.rotateSpeed );

  		var element = scope.domElement;

  		rotateLeft( 2 * Math.PI * rotateDelta.x / element.clientHeight ); // yes, height

  		rotateUp( 2 * Math.PI * rotateDelta.y / element.clientHeight );

  		rotateStart.copy( rotateEnd );

  		scope.update();

  	}

  	function handleMouseMoveDolly( event ) {

  		dollyEnd.set( event.clientX, event.clientY );

  		dollyDelta.subVectors( dollyEnd, dollyStart );

  		if ( dollyDelta.y > 0 ) {

  			dollyOut( getZoomScale() );

  		} else if ( dollyDelta.y < 0 ) {

  			dollyIn( getZoomScale() );

  		}

  		dollyStart.copy( dollyEnd );

  		scope.update();

  	}

  	function handleMouseMovePan( event ) {

  		panEnd.set( event.clientX, event.clientY );

  		panDelta.subVectors( panEnd, panStart ).multiplyScalar( scope.panSpeed );

  		pan( panDelta.x, panDelta.y );

  		panStart.copy( panEnd );

  		scope.update();

  	}

  	function handleMouseWheel( event ) {

  		if ( event.deltaY < 0 ) {

  			dollyIn( getZoomScale() );

  		} else if ( event.deltaY > 0 ) {

  			dollyOut( getZoomScale() );

  		}

  		scope.update();

  	}

  	function handleKeyDown( event ) {

  		var needsUpdate = false;

  		switch ( event.keyCode ) {

  			case scope.keys.UP:
  				pan( 0, scope.keyPanSpeed );
  				needsUpdate = true;
  				break;

  			case scope.keys.BOTTOM:
  				pan( 0, - scope.keyPanSpeed );
  				needsUpdate = true;
  				break;

  			case scope.keys.LEFT:
  				pan( scope.keyPanSpeed, 0 );
  				needsUpdate = true;
  				break;

  			case scope.keys.RIGHT:
  				pan( - scope.keyPanSpeed, 0 );
  				needsUpdate = true;
  				break;

  		}

  		if ( needsUpdate ) {

  			// prevent the browser from scrolling on cursor keys
  			event.preventDefault();

  			scope.update();

  		}


  	}

  	function handleTouchStartRotate( event ) {

  		if ( event.touches.length == 1 ) {

  			rotateStart.set( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );

  		} else {

  			var x = 0.5 * ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX );
  			var y = 0.5 * ( event.touches[ 0 ].pageY + event.touches[ 1 ].pageY );

  			rotateStart.set( x, y );

  		}

  	}

  	function handleTouchStartPan( event ) {

  		if ( event.touches.length == 1 ) {

  			panStart.set( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );

  		} else {

  			var x = 0.5 * ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX );
  			var y = 0.5 * ( event.touches[ 0 ].pageY + event.touches[ 1 ].pageY );

  			panStart.set( x, y );

  		}

  	}

  	function handleTouchStartDolly( event ) {

  		var dx = event.touches[ 0 ].pageX - event.touches[ 1 ].pageX;
  		var dy = event.touches[ 0 ].pageY - event.touches[ 1 ].pageY;

  		var distance = Math.sqrt( dx * dx + dy * dy );

  		dollyStart.set( 0, distance );

  	}

  	function handleTouchStartDollyPan( event ) {

  		if ( scope.enableZoom ) handleTouchStartDolly( event );

  		if ( scope.enablePan ) handleTouchStartPan( event );

  	}

  	function handleTouchStartDollyRotate( event ) {

  		if ( scope.enableZoom ) handleTouchStartDolly( event );

  		if ( scope.enableRotate ) handleTouchStartRotate( event );

  	}

  	function handleTouchMoveRotate( event ) {

  		if ( event.touches.length == 1 ) {

  			rotateEnd.set( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );

  		} else {

  			var x = 0.5 * ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX );
  			var y = 0.5 * ( event.touches[ 0 ].pageY + event.touches[ 1 ].pageY );

  			rotateEnd.set( x, y );

  		}

  		rotateDelta.subVectors( rotateEnd, rotateStart ).multiplyScalar( scope.rotateSpeed );

  		var element = scope.domElement;

  		rotateLeft( 2 * Math.PI * rotateDelta.x / element.clientHeight ); // yes, height

  		rotateUp( 2 * Math.PI * rotateDelta.y / element.clientHeight );

  		rotateStart.copy( rotateEnd );

  	}

  	function handleTouchMovePan( event ) {

  		if ( event.touches.length == 1 ) {

  			panEnd.set( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );

  		} else {

  			var x = 0.5 * ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX );