docs: public void printDualGraph() {
  		System.out.println("============= Dual");
  		int l = BoofMiscOps.numDigits(vertexes.size);
  		String format = "%"+l+"d";
  
  		for( Vertex n : vertexes.toList() ) {
  			ChessboardCorner c = corners.get(n.index);
  			System.out.printf("["+format+"] {%3.0f, %3.0f} ->  90[ ",n.index,c.x,c.y);
  			for (int i = 0; i < n.perpendicular.size(); i++) {
  				Edge e = n.perpendicular.get(i);
  				System.out.printf(format+" ",e.dst.index);
  			}
  			System.out.println("]");
  			System.out.print("                -> 180[ ");
  			for (int i = 0; i < n.parallel.size(); i++) {
  				Edge e = n.parallel.get(i);
  				System.out.printf(format+" ",e.dst.index);
  			}
  			System.out.println("]");
  		}
  	}