anchor.diff:    Map<String, bool> _cpmb = currentlyPressedMouseButtons;
   
     OrbitCamera(this._radius,
  -      [this.azimuth = 0.0, this._polar = 0.0, HTML.Element eventElement = null])
  +      [this.azimuth = 0.0, this.polar = 0.0, HTML.Element eventElement = null])
         : super("camera:orbit") {
       if (eventElement == null) eventElement = HTML.document.body;
       eventElement.onMouseWheel.listen((HTML.WheelEvent e) {
  
positive.code:         //azimuth += e.movement.x*0.01;
          //polar += e.movement.y*0.01;
          azimuth += (mouseX - mouseDownX) * 0.01;
          _polar += (mouseDownY - mouseY) * 0.01;
          mouseDownX = mouseX;
          mouseDownY = mouseY;
        }
  
negative.code: class OrbitCamera extends Camera {
    double _radius;
    double azimuth;
    double polar;
    double roll = 0.0;
    final VM.Vector3 _lookAtPos = new VM.Vector3.zero();
    num mouseWheelFactor = -0.01;
  
  