code: public static Polygon getMultiTilePolygon (MisoSceneMetrics metrics,
                                                 Point sp1, Point sp2)
      {
          int x = Math.min(sp1.x, sp2.x), y = Math.min(sp1.y, sp2.y);
          int width = Math.abs(sp1.x-sp2.x)+1, height = Math.abs(sp1.y-sp2.y)+1;
          return getFootprintPolygon(metrics, x, y, width, height);
      }
docs: Return a screen-coordinates polygon framing the two specified
  tile-coordinate points.