text: THREE.SelectionHelper = ( function () {
  
  	function SelectionHelper( selectionBox, renderer, cssClassName ) {
  
  		this.element = document.createElement( 'div' );
  		this.element.classList.add( cssClassName );
  		this.element.style.pointerEvents = 'none';
  
  		this.renderer = renderer;
  
  		this.startPoint = new THREE.Vector2();
  		this.pointTopLeft = new THREE.Vector2();
  		this.pointBottomRight = new THREE.Vector2();
  
  		this.isDown = false;
  
  		this.renderer.domElement.addEventListener( 'pointerdown', function ( event ) {
  
  			this.isDown = true;
  			this.onSelectStart( event );
  
  		}.bind( this ), false );
  
  		this.renderer.domElement.addEventListener( 'pointermove', function ( event ) {
  
  			if ( this.isDown ) {
  
  				this.onSelectMove( event );
  
  			}
  
  		}.bind( this ), false );
  
  		this.renderer.domElement.addEventListener( 'pointerup', function ( event ) {
  
  			this.isDown = false;
  			this.onSelectOver( event );
  
  		}.bind( this ), false );
  
  	}
  
  	SelectionHelper.prototype.onSelectStart = function ( event ) {
  
  		this.renderer.domElement.parentElement.appendChild( this.element );
  
  		this.element.style.left = event.clientX + 'px';
  		this.element.style.top = event.clientY + 'px';
  		this.element.style.width = '0px';
  		this.element.style.height = '0px';
  
  		this.startPoint.x = event.clientX;
  		this.startPoint.y = event.clientY;
  
  	};
  
  	SelectionHelper.prototype.onSelectMove = function ( event ) {
  
  		this.pointBottomRight.x = Math.max( this.startPoint.x, event.clientX );
  		this.pointBottomRight.y = Math.max( this.startPoint.y, event.clientY );
  		this.pointTopLeft.x = Math.min( this.startPoint.x, event.clientX );
  		this.pointTopLeft.y = Math.min( this.startPoint.y, event.clientY );
  
  		this.element.style.left = this.pointTopLeft.x + 'px';
  		this.element.style.top = this.pointTopLeft.y + 'px';
  		this.element.style.width = ( this.pointBottomRight.x - this.pointTopLeft.x ) + 'px';
  		this.element.style.height = ( this.pointBottomRight.y - this.pointTopLeft.y ) + 'px';
  
  	};
  
  	SelectionHelper.prototype.onSelectOver = function () {
  
  		this.element.parentElement.removeChild( this.element );
  
  	};
  
  	return SelectionHelper;
  
  } )();
  