public double signed_distance(PlaPointFloat p_point){
  double dx=point_b.v_x - point_a.v_x;
  double dy=point_b.v_y - point_a.v_y;
  double det=dy * (p_point.v_x - point_a.v_x) - dx * (p_point.v_y - point_a.v_y);
  double length=Math.sqrt(dx * dx + dy * dy);
  return det / length;
}

public double signed_distance ( PlaPointFloat p_point ) { double dx = point_b . v_x - point_a . v_x ; double dy = point_b . v_y - point_a . v_y ; double det = dy * ( p_point . v_x - point_a . v_x ) - dx * ( p_point . v_y - point_a . v_y ) ; double length = Math . sqrt ( dx * dx + dy * dy ) ; return det / length ; }
returns the signed distance of this line from p_point . the result will be positive , if the line is on the left of p_point , else negative .
