CGAL users discussion list

[Zohar <>]

This is a code snippet which I found in the examples, and should be in the
faq, doc, or a new page of useful cgal utils. Hopefully it would come up by
google:


// Can be used to convert polyhedron from exact to inexact and vice-versa
template <class Polyhedron_input,
class Polyhedron_output>
struct Copy_polyhedron_to 
        : public CGAL::Modifier_base<typename Polyhedron_output::HalfedgeDS>
{
        Copy_polyhedron_to(const Polyhedron_input& in_poly) 
                : in_poly(in_poly) {}

        void operator()(typename Polyhedron_output::HalfedgeDS& out_hds)
        {
                typedef typename Polyhedron_output::HalfedgeDS Output_HDS;
                typedef typename Polyhedron_input::HalfedgeDS Input_HDS;

                CGAL::Polyhedron_incremental_builder_3<Output_HDS> 
builder(out_hds);

                typedef typename Polyhedron_input::Vertex_const_iterator
Vertex_const_iterator;
                typedef typename Polyhedron_input::Facet_const_iterator 
Facet_const_iterator;
                typedef typename 
Polyhedron_input::Halfedge_around_facet_const_circulator
HFCC;

                builder.begin_surface(in_poly.size_of_vertices(),
                        in_poly.size_of_facets(),
                        in_poly.size_of_halfedges());

                for(Vertex_const_iterator
                        vi = in_poly.vertices_begin(), end = 
in_poly.vertices_end();
                        vi != end ; ++vi) 
                {
                        typename Polyhedron_output::Point_3 
p(::CGAL::to_double(
vi->point().x()),
                                ::CGAL::to_double( vi->point().y()),
                                ::CGAL::to_double( vi->point().z()));
                        builder.add_vertex(p);
                }

                typedef CGAL::Inverse_index<Vertex_const_iterator> Index;
                Index index( in_poly.vertices_begin(), 
in_poly.vertices_end());

                for(Facet_const_iterator 
                        fi = in_poly.facets_begin(), end = 
in_poly.facets_end();
                        fi != end; ++fi) 
                {
                        HFCC hc = fi->facet_begin();
                        HFCC hc_end = hc;
                        builder.begin_facet ();
                        do {
                                
builder.add_vertex_to_facet(index[hc->vertex()]);
                                ++hc;
                        } while( hc != hc_end);
                        builder.end_facet();
                }
                builder.end_surface();
        } // end operator()(..)
private:
        const Polyhedron_input& in_poly;
}; // end Copy_polyhedron_to<>

template <class Poly_B, class Poly_A>
void poly_copy(Poly_B& poly_b, const Poly_A& poly_a)
{
        poly_b.clear();
        Copy_polyhedron_to<Poly_A, Poly_B> modifier(poly_a);
        poly_b.delegate(modifier);
} 



--
View this message in context: 
http://cgal-discuss.949826.n4.nabble.com/Example-Convert-polyhedron-from-one-kernel-to-another-tp4514497p4514497.html
Sent from the cgal-discuss mailing list archive at Nabble.com.