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[魏华祎 <>]

  Hi, everyone,

      

     I have a 2d simple triangulation with four vertices: p1 = (0,0),  p2 = (1,0), p3  = (1,1), p4 = ( 0,1),  and two triangles: (p2, p3, p1) and (p4,p1,p3). And I want to construct a object of Triangulation_2 class, explicitly ( not write these information into files, then use >> read them). The following is my code. But at last, I got five finite vertices and three finite faces. I am confused,  can anyone give me some suggestions about it?  Thanks very much! 

    By the way, I follow the code of  the "file_input" member function in Triangulation_data_structure_2.h to write my own code. 

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>

#include <CGAL/IO/Color.h>

#include <CGAL/Triangulation_2.h>

#include <CGAL/Triangulation_face_base_2.h>

#include <CGAL/Triangulation_vertex_base_2.h>

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;

typedef CGAL::Triangulation_vertex_base_2<K> Vb;

typedef CGAL::Triangulation_face_base_2<K> Fb;

typedef CGAL::Triangulation_data_structure_2<Vb,Fb> Tds;

typedef CGAL::Triangulation_2<K,Tds> Triangulation;

typedef Triangulation::Face_handle Face_handle;

typedef Triangulation::Vertex_handle Vertex_handle;

typedef Triangulation::Point Point;

typedef Triangulation::Finite_vertices_iterator Fvi;

int main(){

  int n = 4, m = 2, d = 2;

  std::vector<Point> P(4);

  P[0] = Point(0,0);

  P[1] = Point(1,0);

  P[2] = Point(1,1);

  P[3] = Point(0,1);

  std::vector<Vertex_handle> V(n+1);

  std::vector<Face_handle> F(m);

  Triangulation tri;

  tri.tds().set_dimension(d);

 // if I comment the following two lines, there will four finite vertices, but still three faces

  V[0] = tri.tds().create_vertex(); 

  tri.set_infinite_vertex(V[0]); // set the infinite vertex of tri

 // create the vertex_handles

  for(int i = 1; i< 5;i++){

    V[i] = tri.tds().create_vertex();

    V[i]->set_point(P[i-1]);

  }

 //create the first face and set its vertices

  F[0] = tri.create_face();

  F[0]->set_vertex(0,V[2]);

  V[2]->set_face(F[0]);

  F[0]->set_vertex(1,V[3]);

  V[3]->set_face(F[0]);

  F[0]->set_vertex(2,V[1]);

  V[1]->set_face(F[0]);

  // create the second face and set its vertices

  F[1] = tri.create_face();

  F[1]->set_vertex(0,V[4]);

  V[4]->set_face(F[1]);

  F[1]->set_vertex(1,V[1]);

  V[1]->set_face(F[1]);

  

  F[1]->set_vertex(2,V[3]);

  V[3]->set_face(F[1]);

  // set neighbor information

  F[0]->set_neighbor(0,F[1]);

  F[1]->set_neighbor(0,F[0]);

  std::cout<<tri.number_of_vertices()<<std::endl<<tri.number_of_faces()<<std::endl;

  return 0;

}