CGAL users discussion list

[sanlington <>]

Hi ,Morteza Romoozi
the edges in 2D mesh is hold implicitly,not like the face or the vertex，but you can access the coordinates of edges through the Face_handle and index.
    i pasted the example code from:http://www.cgal.org/Manual/3.5/doc_html/cgal_manual/Mesh_2/Chapter_main.html, and added some codes between the /****...**/ lines to show how to access edge's coordinates:

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Constrained_Delaunay_triangulation_2.h>
#include <CGAL/Triangulation_conformer_2.h>

#include <iostream>

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Constrained_Delaunay_triangulation_2<K> CDT;
typedef CDT::Point Point;
typedef CDT::Vertex_handle Vertex_handle;



int main()
{
  CDT cdt;

  // construct a constrained triangulation
  Vertex_handle
    va = cdt.insert(Point( 5., 5.)),
    vb = cdt.insert(Point(-5., 5.)),
    vc = cdt.insert(Point( 4., 3.)),
    vd = cdt.insert(Point( 5.,-5.)),
    ve = cdt.insert(Point( 6., 6.)),
    vf = cdt.insert(Point(-6., 6.)),
    vg = cdt.insert(Point(-6.,-6.)),
    vh = cdt.insert(Point( 6.,-6.));

  cdt.insert_constraint(va,vb);
  cdt.insert_constraint(vb,vc);
  cdt.insert_constraint(vc,vd);
  cdt.insert_constraint(vd,va);
  cdt.insert_constraint(ve,vf);
  cdt.insert_constraint(vf,vg);
  cdt.insert_constraint(vg,vh);
  cdt.insert_constraint(vh,ve);

  std::cout << "Number of vertices before: "
            << cdt.number_of_vertices() << std::endl;

  // make it conforming Delaunay
  CGAL::make_conforming_Delaunay_2(cdt);

  std::cout << "Number of vertices after make_conforming_Delaunay_2: "
            << cdt.number_of_vertices() << std::endl;

  // then make it conforming Gabriel
  CGAL::make_conforming_Gabriel_2(cdt);

  std::cout << "Number of vertices after make_conforming_Gabriel_2: "
            << cdt.number_of_vertices() << std::endl;

/******* you can access the coordinates of edges like this *******************************/
typedef CDT::Finite_edges_iterator               FEit;  
typedef CDT::Edge                                            Edge; 

for (FEit eit= cdt.finite_edges_begin(); eit!= cdt.finite_edges.end(); eit++ )
{
        Edge e= *eit;
        Point s= e.first->vertex((e.second+1)%3)->point(),
                  t= e.first->vertex((e.second+2)%3)->point();
        std::cout<<"s="<<s<<std::endl
                        <<"t="<<t<<std::endl;
  }
/********************************************************************/

}

在2009-08-02，"Morteza Romoozi" <> 写道：

Hi

i nead a mesher algorithm that mesh a terrain with excepted sites, and can deliver me edges of this mesh.

i visit below link but i dont know how to extract edges of the mesh

http://www.cgal.org/Manual/3.2/doc_html/cgal_manual/Mesh_2/Chapter_main.html

 

 

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