text: /**
   * @author Eberhard Graether / http://egraether.com/
   */
  
  THREE.TrackballControls = function ( object, domElement ) {
  
  	var _this = this;
  	var STATE = { NONE: -1, ROTATE: 0, ZOOM: 1, PAN: 2, TOUCH_ROTATE: 3, TOUCH_ZOOM: 4, TOUCH_PAN: 5 };
  
  	this.object = object;
  	this.domElement = ( domElement !== undefined ) ? domElement : document;
  
  	// API
  
  	this.enabled = true;
  
  	this.screen = { left: 0, top: 0, width: 0, height: 0 };
  
  	this.rotateSpeed = 1.0;
  	this.zoomSpeed = 1.2;
  	this.panSpeed = 0.3;
  
  	this.noRotate = false;
  	this.noZoom = false;
  	this.noPan = false;
  	this.noRoll = false;
  
  	this.staticMoving = false;
  	this.dynamicDampingFactor = 0.2;
  
  	this.minDistance = 0;
  	this.maxDistance = Infinity;
  
  	this.keys = [ 65 /*A*/, 83 /*S*/, 68 /*D*/ ];
  
  	// internals
  
  	this.target = new THREE.Vector3();
  
  	var lastPosition = new THREE.Vector3();
  
  	var _state = STATE.NONE,
  	_prevState = STATE.NONE,
  
  	_eye = new THREE.Vector3(),
  
  	_rotateStart = new THREE.Vector3(),
  	_rotateEnd = new THREE.Vector3(),
  
  	_zoomStart = new THREE.Vector2(),
  	_zoomEnd = new THREE.Vector2(),
  
  	_touchZoomDistanceStart = 0,
  	_touchZoomDistanceEnd = 0,
  
  	_panStart = new THREE.Vector2(),
  	_panEnd = new THREE.Vector2();
  
  	// for reset
  
  	this.target0 = this.target.clone();
  	this.position0 = this.object.position.clone();
  	this.up0 = this.object.up.clone();
  
  	// events
  
  	var changeEvent = { type: 'change' };
  
  
  	// methods
  
  	this.handleResize = function () {
  
  		if ( this.domElement === document ) {
  
  			this.screen.left = 0;
  			this.screen.top = 0;
  			this.screen.width = window.innerWidth;
  			this.screen.height = window.innerHeight;
  
  		} else {
  
  			this.screen = this.domElement.getBoundingClientRect();
  
  		}
  
  	};
  
  	this.handleEvent = function ( event ) {
  
  		if ( typeof this[ event.type ] == 'function' ) {
  
  			this[ event.type ]( event );
  
  		}
  
  	};
  
  	this.getMouseOnScreen = function ( clientX, clientY ) {
  
  		return new THREE.Vector2(
  			( clientX - _this.screen.left ) / _this.screen.width,
  			( clientY - _this.screen.top ) / _this.screen.height
  		);
  
  	};
  
  	this.getMouseProjectionOnBall = function ( clientX, clientY ) {
  
  		var mouseOnBall = new THREE.Vector3(
  			( clientX - _this.screen.width * 0.5 - _this.screen.left ) / (_this.screen.width*.5),
  			( _this.screen.height * 0.5 + _this.screen.top - clientY ) / (_this.screen.height*.5),
  			0.0
  		);
  
  		var length = mouseOnBall.length();
  
  		if ( _this.noRoll ) {
  
  			if ( length < Math.SQRT1_2 ) {
  
  				mouseOnBall.z = Math.sqrt( 1.0 - length*length );
  
  			} else {
  
  				mouseOnBall.z = .5 / length;
  
  			}
  
  		} else if ( length > 1.0 ) {
  
  			mouseOnBall.normalize();
  
  		} else {
  
  			mouseOnBall.z = Math.sqrt( 1.0 - length * length );
  
  		}
  
  		_eye.copy( _this.object.position ).sub( _this.target );
  
  		var projection = _this.object.up.clone().setLength( mouseOnBall.y );
  		projection.add( _this.object.up.clone().cross( _eye ).setLength( mouseOnBall.x ) );
  		projection.add( _eye.setLength( mouseOnBall.z ) );
  
  		return projection;
  
  	};
  
  	this.rotateCamera = function () {
  
  		var angle = Math.acos( _rotateStart.dot( _rotateEnd ) / _rotateStart.length() / _rotateEnd.length() );
  
  		if ( angle ) {
  
  			var axis = ( new THREE.Vector3() ).crossVectors( _rotateStart, _rotateEnd ).normalize(),
  				quaternion = new THREE.Quaternion();
  
  			angle *= _this.rotateSpeed;
  
  			quaternion.setFromAxisAngle( axis, -angle );
  
  			_eye.applyQuaternion( quaternion );
  			_this.object.up.applyQuaternion( quaternion );
  
  			_rotateEnd.applyQuaternion( quaternion );
  
  			if ( _this.staticMoving ) {
  
  				_rotateStart.copy( _rotateEnd );
  
  			} else {
  
  				quaternion.setFromAxisAngle( axis, angle * ( _this.dynamicDampingFactor - 1.0 ) );
  				_rotateStart.applyQuaternion( quaternion );
  
  			}
  
  		}
  
  	};
  
  	this.zoomCamera = function () {
  
  		if ( _state === STATE.TOUCH_ZOOM ) {
  
  			var factor = _touchZoomDistanceStart / _touchZoomDistanceEnd;
  			_touchZoomDistanceStart = _touchZoomDistanceEnd;
  			_eye.multiplyScalar( factor );
  
  		} else {
  
  			var factor = 1.0 + ( _zoomEnd.y - _zoomStart.y ) * _this.zoomSpeed;
  
  			if ( factor !== 1.0 && factor > 0.0 ) {
  
  				_eye.multiplyScalar( factor );
  
  				if ( _this.staticMoving ) {
  
  					_zoomStart.copy( _zoomEnd );
  
  				} else {
  
  					_zoomStart.y += ( _zoomEnd.y - _zoomStart.y ) * this.dynamicDampingFactor;
  
  				}
  
  			}
  
  		}
  
  	};
  
  	this.panCamera = function () {
  
  		var mouseChange = _panEnd.clone().sub( _panStart );
  
  		if ( mouseChange.lengthSq() ) {
  
  			mouseChange.multiplyScalar( _eye.length() * _this.panSpeed );
  
  			var pan = _eye.clone().cross( _this.object.up ).setLength( mouseChange.x );
  			pan.add( _this.object.up.clone().setLength( mouseChange.y ) );
  
  			_this.object.position.add( pan );
  			_this.target.add( pan );
  
  			if ( _this.staticMoving ) {
  
  				_panStart = _panEnd;
  
  			} else {
  
  				_panStart.add( mouseChange.subVectors( _panEnd, _panStart ).multiplyScalar( _this.dynamicDampingFactor ) );
  
  			}
  
  		}
  
  	};
  
  	this.checkDistances = function () {
  
  		if ( !_this.noZoom || !_this.noPan ) {
  
  			if ( _eye.lengthSq() > _this.maxDistance * _this.maxDistance ) {
  
  				_this.object.position.addVectors( _this.target, _eye.setLength( _this.maxDistance ) );
  
  			}
  
  			if ( _eye.lengthSq() < _this.minDistance * _this.minDistance ) {
  
  				_this.object.position.addVectors( _this.target, _eye.setLength( _this.minDistance ) );
  
  			}
  
  		}
  
  	};
  
  	this.update = function () {
  
  		_eye.subVectors( _this.object.position, _this.target );
  
  		if ( !_this.noRotate ) {
  
  			_this.rotateCamera();
  
  		}
  
  		if ( !_this.noZoom ) {
  
  			_this.zoomCamera();
  
  		}
  
  		if ( !_this.noPan ) {
  
  			_this.panCamera();
  
  		}
  
  		_this.object.position.addVectors( _this.target, _eye );
  
  		_this.checkDistances();
  
  		_this.object.lookAt( _this.target );
  
  		if ( lastPosition.distanceToSquared( _this.object.position ) > 0 ) {
  
  			_this.dispatchEvent( changeEvent );
  
  			lastPosition.copy( _this.object.position );
  
  		}
  
  	};
  
  	this.reset = function () {
  
  		_state = STATE.NONE;
  		_prevState = STATE.NONE;
  
  		_this.target.copy( _this.target0 );
  		_this.object.position.copy( _this.position0 );
  		_this.object.up.copy( _this.up0 );
  
  		_eye.subVectors( _this.object.position, _this.target );
  
  		_this.object.lookAt( _this.target );
  
  		_this.dispatchEvent( changeEvent );
  
  		lastPosition.copy( _this.object.position );
  
  	};
  
  	// listeners
  
  	function keydown( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		window.removeEventListener( 'keydown', keydown );
  
  		_prevState = _state;
  
  		if ( _state !== STATE.NONE ) {
  
  			return;
  
  		} else if ( event.keyCode === _this.keys[ STATE.ROTATE ] && !_this.noRotate ) {
  
  			_state = STATE.ROTATE;
  
  		} else if ( event.keyCode === _this.keys[ STATE.ZOOM ] && !_this.noZoom ) {
  
  			_state = STATE.ZOOM;
  
  		} else if ( event.keyCode === _this.keys[ STATE.PAN ] && !_this.noPan ) {
  
  			_state = STATE.PAN;
  
  		}
  
  	}
  
  	function keyup( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		_state = _prevState;
  
  		window.addEventListener( 'keydown', keydown, false );
  
  	}
  
  	function mousedown( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		event.preventDefault();
  		event.stopPropagation();
  
  		if ( _state === STATE.NONE ) {
  
  			_state = event.button;
  
  		}
  
  		if ( _state === STATE.ROTATE && !_this.noRotate ) {
  
  			_rotateStart = _this.getMouseProjectionOnBall( event.clientX, event.clientY );
  			_rotateEnd.copy(_rotateStart)
  
  		} else if ( _state === STATE.ZOOM && !_this.noZoom ) {
  
  			_zoomStart = _this.getMouseOnScreen( event.clientX, event.clientY );
  			_zoomEnd.copy(_zoomStart);
  
  		} else if ( _state === STATE.PAN && !_this.noPan ) {
  
  			_panStart = _this.getMouseOnScreen( event.clientX, event.clientY );
  			_panEnd.copy(_panStart)
  
  		}
  
  		document.addEventListener( 'mousemove', mousemove, false );
  		document.addEventListener( 'mouseup', mouseup, false );
  
  	}
  
  	function mousemove( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		event.preventDefault();
  		event.stopPropagation();
  
  		if ( _state === STATE.ROTATE && !_this.noRotate ) {
  
  			_rotateEnd = _this.getMouseProjectionOnBall( event.clientX, event.clientY );
  
  		} else if ( _state === STATE.ZOOM && !_this.noZoom ) {
  
  			_zoomEnd = _this.getMouseOnScreen( event.clientX, event.clientY );
  
  		} else if ( _state === STATE.PAN && !_this.noPan ) {
  
  			_panEnd = _this.getMouseOnScreen( event.clientX, event.clientY );
  
  		}
  
  	}
  
  	function mouseup( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		event.preventDefault();
  		event.stopPropagation();
  
  		_state = STATE.NONE;
  
  		document.removeEventListener( 'mousemove', mousemove );
  		document.removeEventListener( 'mouseup', mouseup );
  
  	}
  
  	function mousewheel( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		event.preventDefault();
  		event.stopPropagation();
  
  		var delta = 0;
  
  		if ( event.wheelDelta ) { // WebKit / Opera / Explorer 9
  
  			delta = event.wheelDelta / 40;
  
  		} else if ( event.detail ) { // Firefox
  
  			delta = - event.detail / 3;
  
  		}
  
  		_zoomStart.y += delta * 0.01;
  
  	}
  
  	function touchstart( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		switch ( event.touches.length ) {
  
  			case 1:
  				_state = STATE.TOUCH_ROTATE;
  				_rotateStart = _rotateEnd = _this.getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
  				break;
  
  			case 2:
  				_state = STATE.TOUCH_ZOOM;
  				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 );
  				break;
  
  			case 3:
  				_state = STATE.TOUCH_PAN;
  				_panStart = _panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
  				break;
  
  			default:
  				_state = STATE.NONE;
  
  		}
  
  	}
  
  	function touchmove( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		event.preventDefault();
  		event.stopPropagation();
  
  		switch ( event.touches.length ) {
  
  			case 1:
  				_rotateEnd = _this.getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
  				break;
  
  			case 2:
  				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 )
  				break;
  
  			case 3:
  				_panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
  				break;
  
  			default:
  				_state = STATE.NONE;
  
  		}
  
  	}
  
  	function touchend( event ) {
  
  		if ( _this.enabled === false ) return;
  
  		switch ( event.touches.length ) {
  
  			case 1:
  				_rotateStart = _rotateEnd = _this.getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
  				break;
  
  			case 2:
  				_touchZoomDistanceStart = _touchZoomDistanceEnd = 0;
  				break;
  
  			case 3:
  				_panStart = _panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
  				break;
  
  		}
  
  		_state = STATE.NONE;
  
  	}
  
  	this.domElement.addEventListener( 'contextmenu', function ( event ) { event.preventDefault(); }, false );
  
  	this.domElement.addEventListener( 'mousedown', mousedown, false );
  
  	this.domElement.addEventListener( 'mousewheel', mousewheel, false );
  	this.domElement.addEventListener( 'DOMMouseScroll', mousewheel, false ); // firefox
  
  	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();
  
  };
  
  THREE.TrackballControls.prototype = Object.create( THREE.EventDispatcher.prototype );