CGAL users discussion list

[Pierre Alliez <>]

hi Abel,

you can always copy the whole mesh using the copy constructor of the 
polyhedron.

you can always elaborate upon a simple mesh builder that takes a 
triangle soup using the exemple class attached.

      Make_triangle_soup<Polyhedron,Kernel,Iterator> soup_builder;
      soup_builder.run(triangles.begin(),triangles.end(),*pSoup);

or write your own builder specialized to one part of the mesh.


Abel Alonso a écrit :
> Hi!
>
> I'm working with the class Polyhedron_3 to implement a Mesh Editor and 
> when the user performs an operation which involves a hole I would like 
> to come back to the previous state of the mesh. I have a buffer of 
> triangles of that previous mesh state, but I cannot reconstruct the mesh 
> by adding all of these triangles using the make_triangle method, but I 
> cannot add a triangle which has two points inserted in the polyhedron.
>
> So, my question is:
>
> Does exists any method or way to construct a Polyhedron from a triangle 
> list?
>
> If it isn't, I would like to know if is there any way to copy a 
> Polyhedron object to another one, without memory sharing between them.
>
> Thanks in advance and congrats for this great library,
>
> Abel.


#ifndef _MAKE_SOUP_
#define _MAKE_SOUP_

#include <CGAL/Modifier_base.h>
#include <CGAL/Polyhedron_incremental_builder_3.h>

template <class HDS,class Polyhedron,class Kernel,class InputIterator>
class CModifierTriangleSoup : public CGAL::Modifier_base<HDS>
{
private:
  typedef typename Kernel::Triangle_3 Triangle;
  typedef typename CGAL::Polyhedron_incremental_builder_3<HDS> builder;
  InputIterator m_begin, m_end;

public:

  // life cycle
  CModifierTriangleSoup(InputIterator begin,InputIterator end)
    : m_begin(begin), m_end(end)
  {
  }
  ~CModifierTriangleSoup() {}

  // make a polygon soup
  void operator()( HDS& hds)
  {
    builder B(hds,true);
    B.begin_surface(3,1,6);

    int index = 0;
    InputIterator it;
    for(it = m_begin; it != m_end; it++)
    {
      const Triangle& triangle = *it;

      B.add_vertex(triangle[0]);
      B.add_vertex(triangle[1]);
      B.add_vertex(triangle[2]);

      B.begin_facet();
      B.add_vertex_to_facet(index++);
      B.add_vertex_to_facet(index++);
      B.add_vertex_to_facet(index++);
      B.end_facet();
    }
    B.end_surface();
  }
};

template <class Polyhedron,class Kernel,class InputIterator>
class Make_triangle_soup
{
public:
  typedef typename Polyhedron::HalfedgeDS HalfedgeDS;
  Make_triangle_soup() {}
  ~Make_triangle_soup() {}

public:
  void run(InputIterator begin,
    InputIterator end,
    Polyhedron &output)
  {
    CModifierTriangleSoup<HalfedgeDS,Polyhedron,Kernel,InputIterator> 
soup(begin,end);
    output.delegate(soup);
  }
};

#endif // _MAKE_SOUP_