question: 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 ; }
target:  creates a polyline consisting of 3 lines