benchmarks/polygons/java/code/ClockSort.java

   1
   2 /**
   3  *
   4  * @author Johan
   5  */
   6 public class ClockSort extends PolygonSorter {
   7
   8     public ClockSort(double[][] points) {
   9         super(points);
  10     }
  11
  12     /**
  13      * Compare polygon vertices in clock wise order starting at six hour. If two
  14      * points share the same rad, then the farest to the center is chosen.
  15      *
  16      * @param a: a point to compare
  17      * @param b: a second point to compare
  18      * @return
  19      */
  20     @Override
  21     public int compare(PointDouble a, PointDouble b) {
  22         if (a.x - center.x >= 0 && b.x - center.x < 0) {
  23             return +1;
  24         }
  25         if (a.x - center.x < 0 && b.x - center.x >= 0) {
  26             return -1;
  27         }
  28         if (a.x - center.x == 0 && b.x - center.x == 0) {
  29             if (a.y - center.y >= 0 || b.y - center.y >= 0) {
  30                 return (a.y > b.y) ? +1 : -1;
  31             }
  32             return (b.y > a.y) ? +1 : -1;
  33         }
  34
  35         // compute the cross product of vectors (center -> a) x (center -> b)
  36         double det = (a.x - center.x) * (b.y - center.y) - (b.x - center.x) * (a.y - center.y);
  37         if (det < 0.0d) {
  38             return +1;
  39         }
  40         if (det > 0.0d) {
  41             return -1;
  42         }
  43
  44         // points a and b are on the same line from the center
  45         // check which point is closer to the center
  46         double d1 = (a.x - center.x) * (a.x - center.x) + (a.y - center.y) * (a.y - center.y);
  47         double d2 = (b.x - center.x) * (b.x - center.x) + (b.y - center.y) * (b.y - center.y);
  48         return (d1 > d2) ? +1 : -1;
  49     }
  50 }