@Override public ShapeTileSimplex to_Simplex(){
  if (is_empty())   return ShapeTileSimplex.EMPTY;
  ArrayList<PlaLineInt> line_arr=new ArrayList<PlaLineInt>(4);
  line_arr.add(new PlaLineInt(box_ll,PlaDirection.RIGHT));
  line_arr.add(new PlaLineInt(box_ur,PlaDirection.UP));
  line_arr.add(new PlaLineInt(box_ur,PlaDirection.LEFT));
  line_arr.add(new PlaLineInt(box_ll,PlaDirection.DOWN));
  return new ShapeTileSimplex(line_arr);
}

@ Override public ShapeTileSimplex to_Simplex ( ) { if ( is_empty ( ) ) return ShapeTileSimplex . EMPTY ; ArrayList < PlaLineInt > line_arr = new ArrayList < PlaLineInt > ( 4 ) ; line_arr . add ( new PlaLineInt ( box_ll , PlaDirection . RIGHT ) ) ; line_arr . add ( new PlaLineInt ( box_ur , PlaDirection . UP ) ) ; line_arr . add ( new PlaLineInt ( box_ur , PlaDirection . LEFT ) ) ; line_arr . add ( new PlaLineInt ( box_ll , PlaDirection . DOWN ) ) ; return new ShapeTileSimplex ( line_arr ) ; }
returns an object of class simplex defining the same shape
