private function onEnterFrame(event:Event):void
    {
     var angleX:Number = (mouseY - vpY) * .001;
     var angleY:Number = (mouseX - vpX) * .001;
     for(var i:uint = 0; i < points.length; i++)
     {
      var point:animation_ch16_Point3D = points[i];
      point.rotateX(angleX);
      point.rotateY(angleY);
     }
     
     graphics.clear();
     for(i = 0; i < triangles.length; i++)
     {
      triangles[i].draw(graphics);
     }
    }
   }
  }