CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 09/04/2012 05:24 PM, Mathieu Westphal wrote:
> I have a polyhedron_3 (with only triangles in it ) and i want to create
> a vtkPolyData with it.
>
> I can extract Points from the polyhedron without problem and inject them
> into the vtkPolyData
>
> However i see no evident way to extract cells (facets in CGAL?)
Looking at this page:
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Polyhedron_ref/Class_Polyhedron_3.htm

given a polyhefron Pyou can see that the range
P.facets_begin(), P.facets_end() is what you are looking for.

To access the vertices, given a facet f,

Halfedge_handle h=f.halhedge()
do{
  h->vertex();//access the vertex
  h->vertex()->point();//access the point
  h=h->next();
}while (h!=f.halhedge());

To associate an id to each vertex you can use a 
std::map<Vertex_handle,unsigned> for example or use an
item class with id like Polyhedron_items_with_id_3.

http://www.cgal.org/Manual/latest/doc_html/cgal_manual/BGL_ref/Class_Polyhedron_items_with_id_3.html

Sebastien.

> vtkPolyData need for each cell, the id of constituing points.
>
> Is there any way to find facets from one points? or points from one facet?