Add an example with a user defined points class

Spatial_sorting/examples/Spatial_sorting/myPoint.cpp

@@ -0,0 +1,62 @@
+#include <CGAL/spatial_sort.h>
+
+struct MyPoint {
+  double x,y;
+
+  MyPoint()
+    : x(0), y(0)
+  {}
+
+  MyPoint(double x, double y)
+    : x(x), y(y)
+  {}
+};
+
+
+struct MyLessX {
+
+  bool operator()(const MyPoint& p, const MyPoint& q) const
+  {
+    return p.x < q.x;
+  }
+
+};
+
+struct MyLessY {
+
+  bool operator()(const MyPoint& p, const MyPoint& q) const
+  {
+    return p.y < q.y;
+  }
+
+};
+
+struct MySpatialSortingTraits {
+
+  typedef MyPoint Point_2;
+
+  typedef MyLessX Less_x_2;
+  typedef MyLessY Less_y_2;
+  
+  Less_x_2 less_x_2_object() const
+  {
+    return Less_x_2();
+  }
+
+  Less_y_2 less_y_2_object() const
+  {
+    return Less_y_2();
+  }
+};
+
+int main()
+{
+  MyPoint points[2];
+
+  points[0] = MyPoint(78,12);
+  points[1] = MyPoint(3,121);
+  MySpatialSortingTraits sst;
+  CGAL::spatial_sort(points, points+2, sst);
+  std::cerr << "done" << std::endl;
+  return 0;
+}