CGAL users discussion list

[babaOroms <>]

Hi everybody,
I have a question before going in depth in my code.
I have a set of 3D points in the same plane. With the CGAL framework, it's
impossible to do 3D polygons so I have chosen to do a 3D polyhedron with my
3D points. The result is on this picture :
http://cgal-discuss.949826.n4.nabble.com/file/n4655791/poly1.png 
The construction of this polyhedron is :

template <class HDS>
void Build_polygon<HDS>::operator()( HDS& hds )
{
    if (!polygon)
        return;

    // Postcondition: `hds' is a valid polyhedral surface.
    CGAL::Polyhedron_incremental_builder_3<HDS> B( hds, true);
    typedef typename HDS::Vertex   Vertex;
    typedef typename Vertex::Point Point;

    B.begin_surface( polygon->points().count(), 1, 0); //Surface with
several points

    foreach (RPoint3d* p, polygon->points()) { //iterates all points
        B.add_vertex(Point(p->x(), p->y(), p->z()));
    }
    B.begin_facet();
    for (int i = 0; i < polygon->points().count(); i++)
        B.add_vertex_to_facet( i);
    B.end_facet();
    B.end_surface();
}

Now I need to have the intersection between this polyhedron and a plane :
Tree tree(polyhedron()->facets_begin(),polyhedron()->facets_end());
Point p((FT)0.0, (FT)0.0, z);
Plane plane(p,normal);
std::list<Object_and_primitive_id> intersections;
tree.all_intersections(plane,std::back_inserter(intersections));

This code crash but if I declare several polyhedron of 3 points instead, the
intersection works.

The result of the intersection I need is a segment.

So to resume, is the polyhedron the best way to have a segment as result ?
Does exists another class instead ?

Laurent Rineau said to me in other topic that I can do 3D triangulation of
my polyhedron. The result is not that I am expected (see the following
picture) :
http://cgal-discuss.949826.n4.nabble.com/file/n4655791/poly2.png 
The triangulation gives facets at the exterior of my polehydron.
The good news is that the intersections algorithm works.

Thanks in advance for your advices



--
View this message in context: 
http://cgal-discuss.949826.n4.nabble.com/Is-it-the-right-way-to-do-that-tp4655791.html
Sent from the cgal-discuss mailing list archive at Nabble.com.