CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

When you are calling refine_mesh, cdt is modified and contains the mesh.
You have to refer to the documentation of 2D triangulations for
iterating over faces for examples.
See:
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Triangulation_2/Chapter_main.html
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Mesh_2_ref/Concept_DelaunayMeshFaceBase_2.html#Cross_link_anchor_1425

For example:

Triangulation t;

Triangulation::Finite_faces_iterator fc = t.finite_faces_begin();
for( ; fc != t.finite_faces_end(); ++fc)
  if (fc->is_in_domain()){
    std::cout << fc->vertex(0)->point()
              << fc->vertex(1)->point()
              << fc->vertex(2)->point() << std::endl;
  }



ppmm wrote:
> Hello,
>
> I am new to CGAL. I would like to use CGAL to create the 2D meshes for FEM
> analysis.
>
> My question is how to get the mesh information from the generated mesh, such
> as point coordinate and each zone is defined by which three points.
>
> For example, how to get those information from the mesh_class.cpp example
> listed below.
>
> Thanks a lot for your help.
>
>
>
>
> #include <CGAL/Delaunay_mesh_size_criteria_2.h>
>
> #include <iostream>
>
> typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
> typedef CGAL::Triangulation_vertex_base_2<K> Vb;
> typedef CGAL::Delaunay_mesh_face_base_2<K> Fb;
> typedef CGAL::Triangulation_data_structure_2<Vb, Fb> Tds;
> typedef CGAL::Constrained_Delaunay_triangulation_2<K, Tds> CDT;
> typedef CGAL::Delaunay_mesh_size_criteria_2<CDT> Criteria;
> typedef CGAL::Delaunay_mesher_2<CDT, Criteria> Mesher;
>
> typedef CDT::Vertex_handle Vertex_handle;
> typedef CDT::Point Point;
>
> int main()
> {
>   CDT cdt;
>
>   Vertex_handle va = cdt.insert(Point(-4,0));
>   Vertex_handle vb = cdt.insert(Point(0,-1));
>   Vertex_handle vc = cdt.insert(Point(4,0));
>   Vertex_handle vd = cdt.insert(Point(0,1));
>   cdt.insert(Point(2, 0.6));
>
>   cdt.insert_constraint(va, vb);
>   cdt.insert_constraint(vb, vc);
>   cdt.insert_constraint(vc, vd);
>   cdt.insert_constraint(vd, va);
>
>   std::cout << "Number of vertices: " << cdt.number_of_vertices() <<
> std::endl;
>
>   std::cout << "Meshing the triangulation with default criterias..."
>             << std::endl;
>
>   Mesher mesher(cdt);
>   mesher.refine_mesh();
>
>   std::cout << "Number of vertices: " << cdt.number_of_vertices() <<
> std::endl;
>
>   std::cout << "Meshing with new criterias..." << std::endl;
>   // 0.125 is the default shape bound. It corresponds to abound 20.6 degree.
>   // 0.5 is the upper bound on the length of the longuest edge.
>   // See reference manual for Delaunay_mesh_size_traits_2<K>.
>   mesher.set_criteria(Criteria(0.125, 0.5));
>   mesher.refine_mesh();
>
>   std::cout << "Number of vertices: " << cdt.number_of_vertices() <<
> std::endl;
> }