Weighted AS2 with CGAL

test_WAS2.cpp

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>

#include <CGAL/Alpha_shape_2.h>
#include <CGAL/Alpha_shape_face_base_2.h>
#include <CGAL/Alpha_shape_vertex_base_2.h>
#include <CGAL/Regular_triangulation_2.h>

#include <fstream>
#include <iostream>
#include <list>
#include <vector>

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;

typedef K::FT                                               FT;
typedef K::Point_2                                          Point;
typedef K::Weighted_point_2                                 Weighted_point;
typedef K::Segment_2                                        Segment;

typedef CGAL::Regular_triangulation_vertex_base_2<K>        Rvb;
typedef CGAL::Alpha_shape_vertex_base_2<K,Rvb>              Vb;
typedef CGAL::Regular_triangulation_face_base_2<K>          Rf;
typedef CGAL::Alpha_shape_face_base_2<K,Rf>                 Fb;
typedef CGAL::Triangulation_data_structure_2<Vb,Fb>         Tds;
typedef CGAL::Regular_triangulation_2<K,Tds>                Triangulation_2;
typedef CGAL::Alpha_shape_2<Triangulation_2>                Alpha_shape_2;

typedef Alpha_shape_2::Alpha_shape_edges_iterator           Alpha_shape_edges_iterator;

template <class OutputIterator>
void alpha_edges(const Alpha_shape_2& A, OutputIterator out)
{
  Alpha_shape_edges_iterator it = A.alpha_shape_edges_begin(),
                             end = A.alpha_shape_edges_end();
  for( ; it!=end; ++it)
    *out++ = A.segment(*it);
}

// Reads a list of points and returns a list of segments corresponding to
// the weighted Alpha Shape.
int main()
{
  std::vector<Weighted_point> wpoints;
  wpoints.push_back(Weighted_point(Point(4, 5.7), FT(16)));
  wpoints.push_back(Weighted_point(Point(2.5, 5), FT(4)));
  wpoints.push_back(Weighted_point(Point(3, 3), FT(0)));
  wpoints.push_back(Weighted_point(Point(6, 4), FT(-9)));
  wpoints.push_back(Weighted_point(Point(8, 3), FT(0)));

  Alpha_shape_2 A(wpoints.begin(), wpoints.end(), FT(10000), Alpha_shape_2::GENERAL);

  std::vector<Segment> segments;
  alpha_edges(A, std::back_inserter(segments));

  std::cout << "Alpha Shape computed" << std::endl;
  std::cout << segments.size() << " alpha shape edges" << std::endl;
  std::cout << "Optimal alpha: " << *A.find_optimal_alpha(1)<<std::endl;

  std::cout << "Faces... " << std::endl;
  for(Alpha_shape_2::Finite_faces_iterator face_it = A.faces_begin();
                                           face_it != A.faces_end(); ++face_it)
  {
    std::cout << "face: " << std::endl
                          << "\t" << face_it->vertex(0)->point() << std::endl
                          << "\t" << face_it->vertex(1)->point() << std::endl
                          << "\t" << face_it->vertex(2)->point() << std::endl;
    std::cout << "squared radius: "
              << K().compute_squared_radius_smallest_orthogonal_circle_2_object()(
                   face_it->vertex(0)->point(), face_it->vertex(1)->point(), face_it->vertex(2)->point())
              << std::endl;
    std::cout << "AS sq_r: " << A.squared_radius(face_it) << std::endl;
  }

  std::cout << "alpha values" << std::endl;
  for(Alpha_shape_2::Alpha_iterator alph_it = A.alpha_begin();
                                    alph_it != A.alpha_end(); ++alph_it)
  {
    std::cout << "value: " << *alph_it << std::endl;
  }

  return 0;
}