code: public final void addRing(double xy[]) {
  		for (int i = 2; i < xy.length; i += 2) {
  			addEdge(xy[i-2], xy[i - 1], xy[i], xy[i + 1]);
  		}
  	}
docs: Adds edges of the ring to the rasterizer.
  @param xy interleaved coordinates x1, y1, x2, y2,...