Add criterion.h, where tree building oracle functors will be added

Octree/include/CGAL/Octree.h

@@ -28,6 +28,7 @@
 //#include <CGAL/license/Implicit_surface_reconstruction_3.h>
 
 #include <CGAL/Octree/Octree_node.h>
+#include <CGAL/Octree/Criterion.h>
 
 #include <CGAL/bounding_box.h>
 #include <boost/iterator/transform_iterator.hpp>

Octree/include/CGAL/Octree/Criterion.h

@@ -0,0 +1,62 @@
+
+#ifndef OCTREE_CRITERION_H
+#define OCTREE_CRITERION_H
+
+#include <CGAL/Octree/Octree_node.h>
+
+/*
+
+typedef Octree_node<Kernel, PointRange> Node;
+
+// Possible criterions
+struct Stop_at_max_depth {
+  std::size_t max_depth;
+
+  Stop_at_max_depth(const std::size_t &max_depth) : max_depth(max_depth) {}
+
+  bool operator()(const Node &n) const {
+    return n.depth() == max_depth; // not sure you can know that from node only,
+    // otherwise your criterion could also take a
+    // reference to the full octree as parameter
+  }
+};
+
+struct Stop_at_max_number_of_points {
+  std::size_t max_nb_points;
+
+  Stop_at_max_number_of_points(const std::size_t &max_nb_points)
+          : max_nb_points(max_nb_points) {}
+
+  bool operator()(const Node &n) const {
+    return n.number_of_points() // internally, the node can use std::distance(begin, end)
+           < max_nb_points;
+  }
+};
+
+// Just for an example using outside info (like a normal map)
+// The normals remain unknown to the octree but are used for construction
+struct Stop_at_normal_deviation {
+  Normal_map normal_map;
+  FT max_dev;
+
+  Stop_at_normal_deviation(Normal_map normal_map,
+                           FT max_dev)
+          : normal_map(normal_map), max_dev(max_dev) {}
+
+  bool operator()(const Node &n) const {
+    FT dev = 0;
+
+    for (Iterator it = n.begin(); it != n.end(); ++it)
+      dev += compute_deviation(get(normal_map, *it)); // whatever compute_deviation is :)
+
+    // if your node defines begin() and end(), you can also use a C++11 loop:
+    // for (const Range_type& r : n)
+    //   dev += compute_deviation(get (normal_map, r));
+
+    return dev < max_dev;
+  }
+};
+
+*/
+
+#endif //OCTREE_CRITERION_H