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["Sebastien Loriot (GeometryFactory)" <>]

The infinite vertex is already present in the triangulation even when 
empty, so you don't need to create it.

S.


魏华祎 wrote:
>   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;
> }