EdgeToAngleComparator.java

package com.revolsys.geometry.graph;

import java.util.Comparator;

import com.revolsys.math.Angle;

/**
 * The EdgeToAngleComparator class is used to return edges in a clockwise order.
 *
 * @author Paul Austin
 * @param <T> The type of object stored on the edges in the graph.
 */
public class EdgeToAngleComparator<T> implements Comparator<Edge<T>> {
  private static final EdgeToAngleComparator<?> INSTANCE = new EdgeToAngleComparator<>();

  @SuppressWarnings("unchecked")
  public static <T> EdgeToAngleComparator<T> get() {
    return (EdgeToAngleComparator<T>)INSTANCE;
  }

  /**
   * Construct a new EdgeToAngleComparator.
   */
  public EdgeToAngleComparator() {
  }

  /**
   * Compare the to angle for two edges.
   *
   * @param edge1 The first edge.
   * @param edge2 The second edge.
   * @see Angle#getTurn(double, double)
   */
  @Override
  public int compare(final Edge<T> edge1, final Edge<T> edge2) {
    final double angle1 = edge1.getToAngle();
    final double angle2 = edge2.getToAngle();
    return Angle.getTurn(angle1, angle2);
  }
}