public static int which_side_pp(double x0, double y0, double x1, double y1, double px, double py){
		int side;
		double dot = (y0 - y1)*(px - x0) + (x1 - x0)*(py - y0);

		if(dot < -ACCY)
			side = PLANE_INSIDE;
		else if(dot > ACCY)
			side = PLANE_OUTSIDE;
		else 
			side = ON_PLANE;
		return side;
	}