Spatial_searching/searching_with_point_with_info_inplace.cpp

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Search_traits_3.h>
#include <CGAL/Search_traits_adapter.h>
#include <CGAL/point_generators_3.h>
#include <CGAL/Orthogonal_k_neighbor_search.h>
#include <boost/iterator/counting_iterator.hpp>
#include <utility>

typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef Kernel::Point_3 Point_3;

//definition of a non-mutable lvalue property map,
//with the get function as a friend function to give it
//access to the private member
class My_point_property_map{
  const std::vector<Point_3>& points;
public:
  typedef Point_3 value_type;
  typedef const value_type& reference;
  typedef std::size_t key_type;
  typedef boost::lvalue_property_map_tag category;  

  My_point_property_map(const std::vector<Point_3>& pts):points(pts){}

  reference operator[](key_type k) const {return points[k];}

  friend reference get(const My_point_property_map& ppmap,key_type i) 
  {return ppmap[i];}
};


typedef CGAL::Random_points_in_cube_3<Point_3>                               Random_points_iterator;
typedef CGAL::Search_traits_3<Kernel>                                        Traits_base;
typedef CGAL::Search_traits_adapter<std::size_t,My_point_property_map,Traits_base> Traits;


typedef CGAL::Orthogonal_k_neighbor_search<Traits>                      K_neighbor_search;
typedef K_neighbor_search::Tree                                         Tree;
typedef Tree::Splitter                                                  Splitter;
typedef K_neighbor_search::Distance                                     Distance;

int main() {
  const unsigned int K = 5;
  // generator for random data points in the cube ( (-1,-1,-1), (1,1,1) )
  Random_points_iterator rpit( 1.0);
  std::vector<Point_3> points;
  
  points.push_back(Point_3(*rpit++));
  points.push_back(Point_3(*rpit++));
  points.push_back(Point_3(*rpit++));
  points.push_back(Point_3(*rpit++));
  points.push_back(Point_3(*rpit++));
  points.push_back(Point_3(*rpit++));
  points.push_back(Point_3(*rpit++));

  My_point_property_map ppmap(points);

  // Insert number_of_data_points in the tree
  Tree tree(
    boost::counting_iterator<std::size_t>(0),
    boost::counting_iterator<std::size_t>(points.size()),
    Splitter(),
    Traits(ppmap)
  );
  Point_3 query(0.0, 0.0, 0.0);
  Distance tr_dist(ppmap);

  // search K nearest neighbours
  K_neighbor_search search(tree, query, K,0,true,tr_dist);
  for(K_neighbor_search::iterator it = search.begin(); it != search.end(); it++){
    std::cout << " d(q, nearest neighbor)=  "
          << tr_dist.inverse_of_transformed_distance(it->second) << " " 
              << points[it->first] << " " << it->first << std::endl;
  }
  return 0;
}