Examples of com.vividsolutions.jts.planargraph.DirectedEdge.compareTo()

com.vividsolutions.jts.planargraph.DirectedEdge.compareTo()

Returns 1 if this DirectedEdge has a greater angle with the positive x-axis than b", 0 if the DirectedEdges are collinear, and -1 otherwise.

Using the obvious algorithm of simply computing the angle is not robust, since the angle calculation is susceptible to roundoff. A robust algorithm is:

first compare the quadrants. If the quadrants are different, it it trivial to determine which vector is "greater".
if the vectors lie in the same quadrant, the robust {@link CGAlgorithms#computeOrientation(Coordinate,Coordinate,Coordinate)}function can be used to decide the relative orientation of the vectors.

  public void testDirectedEdgeComparator() {
    DirectedEdge d1 = new DirectedEdge(new Node(new Coordinate(0, 0)),
        new Node(new Coordinate(10, 10)), new Coordinate(10, 10), true);
    DirectedEdge d2 = new DirectedEdge(new Node(new Coordinate(0, 0)),
        new Node(new Coordinate(20, 20)), new Coordinate(20, 20), false);
    assertEquals(0, d2.compareTo(d1));
  }


  public void testDirectedEdgeToEdges() {
    DirectedEdge d1 = new DirectedEdge(new Node(new Coordinate(0, 0)),
        new Node(new Coordinate(10, 10)), new Coordinate(10, 10), true);

All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.