CGAL users discussion list

[Laurent Le Guillou <>]

Hi all,

I am trying to attach some extra information (in fact, dynamic
information like speed, density, mass, elasticity, etc...) to all
vertices, facets and edges of a Polyhedron structure.

I tried different ways but I could not find the proper one
to do that with CGAL.

Here follows my last attempt. I do not understand why I can
easily extend Facets but not Vertices the same way.
What is the problem ? How should I do ?

May be there another CGAL 3D structure better suited for my
problem, but I did not find it.

Thanks in advance for your help.

Laurent
-----------------------------------------------------------------------

#include <CGAL/Cartesian.h>
#include <CGAL/Polyhedron_3.h>

using std::cout;
using std::endl;

// A vertex type with dynamic information.
template <class Refs>
struct My_vertex : public CGAL::HalfedgeDS_vertex_base<Refs> {
  double vx, vy, vz;
};

// A face type with more information.
template <class Refs>
struct My_face : public CGAL::HalfedgeDS_face_base<Refs> {
  double density;
};

//An items type using my face (and my vertex)
struct My_items : public CGAL::Polyhedron_items_3 {

   template <class Refs, class Traits>             // The problem
   struct Vertex_wrapper {                         // is here
     typedef My_vertex<Refs> Vertex;               //
   };

  template <class Refs, class Traits>
  struct Face_wrapper {
    typedef My_face<Refs> Face;
  };

};

typedef CGAL::Cartesian<double>               Kernel;
typedef CGAL::Polyhedron_3<Kernel, My_items>  Polyhedron;
typedef Polyhedron::Vertex_iterator           Vertex_iterator;
typedef Polyhedron::Facet_iterator            Facet_iterator;
typedef Polyhedron::Halfedge_handle           Halfedge_handle;
typedef CGAL::Aff_transformation_3<Kernel>    Transformation;
typedef CGAL::Vector_3<Kernel>                Vector;
typedef CGAL::Point_3<Kernel>                 Point;
typedef Polyhedron::Halfedge::Halfedge_around_facet_circulator
Halfedge_around_facet_circulator;



int main() {
  Point p( 1.0, 0.0, 0.0);
  Point q( 0.0, 1.0, 0.0);
  Point r( 0.0, 0.0, 1.0);
  Point s( 0.0, 0.0, 0.0);

  double density[] = { 1.2, 1.3, 1.4, 1.5 };

  Polyhedron P;
  Halfedge_handle h = P.make_tetrahedron(p, q, r, s);

  int i=0;
  for(Facet_iterator f = P.facets_begin() ;
      f != P.facets_end() ; f++, i++) {
    f->density = density[i];
  }

  for(Vertex_iterator v = P.vertices_begin() ;
      v != P.vertices_end() ; v++) {
    v->vx = v->vy = v->vz = 0.0;
    cout << (*v).point() << endl;
  }

  for(Facet_iterator f = P.facets_begin() ;
        f != P.facets_end() ; f++) {
    cout << "facet: " << endl;
    cout << "   density: " << f->density << endl;
  }

  return 0;
}



-----------------------------------------------------------------------
  Laurent LE GUILLOU                      Tel +33 1 44 27 39 93
  

                      Fax +33 1 44 27 46 38
  


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