docs: function(x1, y1, x2, y2, px, py)
      {
  		x2 -= x1;
  		y2 -= y1;
  		px -= x1;
  		py -= y1;
  		var ccw = px * y2 - py * x2;
  		
  		if (ccw == 0.0)
  		{
  		    ccw = px * x2 + py * y2;
  		    
  		    if (ccw > 0.0)
  		    {
  				px -= x2;
  				py -= y2;
  				ccw = px * x2 + py * y2;
  				
  				if (ccw < 0.0)
  				{
  				    ccw = 0.0;
  				}
  		    }
  		}
  		
  		return (ccw < 0.0) ? -1 : ((ccw > 0.0) ? 1 : 0);
      }