public Polyline(PlaPointInt p_from_corner,PlaPointInt p_to_corner){
  if (p_from_corner.equals(p_to_corner))   throw new IllegalArgumentException(classname + "C must contain at least 2 different points");
  lines_list=new ArrayList<PlaLineInt>(3);
  PlaDirection dir=new PlaDirection(p_from_corner,p_to_corner);
  lines_list.add(new PlaLineInt(p_from_corner,dir.rotate_45_deg(2)));
  lines_list.add(new PlaLineInt(p_from_corner,p_to_corner));
  lines_list.add(new PlaLineInt(p_to_corner,dir.rotate_45_deg(2)));
  corners_allocate(corner_count());
  precalculated_corners[0]=p_from_corner;
  precalculated_corners[1]=p_to_corner;
}

public Polyline ( PlaPointInt p_from_corner , PlaPointInt p_to_corner ) { if ( p_from_corner . equals ( p_to_corner ) ) throw new IllegalArgumentException ( classname + "C must contain at least 2 different points" ) ; lines_list = new ArrayList < PlaLineInt > ( 3 ) ; PlaDirection dir = new PlaDirection ( p_from_corner , p_to_corner ) ; lines_list . add ( new PlaLineInt ( p_from_corner , dir . rotate_45_deg ( 2 ) ) ) ; lines_list . add ( new PlaLineInt ( p_from_corner , p_to_corner ) ) ; lines_list . add ( new PlaLineInt ( p_to_corner , dir . rotate_45_deg ( 2 ) ) ) ; corners_allocate ( corner_count ( ) ) ; precalculated_corners [ 0 ] = p_from_corner ; precalculated_corners [ 1 ] = p_to_corner ; }
creates a polyline consisting of 3 lines
