CGAL users discussion list

[Stephane Tayeb <>]

Benjamin Bouscasse wrote:
> OK, it compiles well now!
> Thanks for the tip, so it means that the C3T3::iterator runs only on finite
> cells?
> Because for a similar application in 2D I have to add an
> "if(fit->is_in_domain())" to select only the faces inside the meshed domain.
> So I thought that "cit->is_in_complex()" was the 3D equivalent.
>
> Thanks for the fast response,
> Ben

Yes, C3T3::Cell_iterator iterates over cells of the triangulation which 
belongs to the c3t3 (i.e. which verify c3t3.is_in_complex(c)).

If you iterate over the cell of the triangulation, using 
C3T3::Triangulation::Cell_iterator, then you will have to check whether 
the cell is in complex or not. In the 2D case, you were maybe iterating 
on triangulation facets ?

Stéphane.

> 2010/5/20 Stephane Tayeb 
> <>
>
> > N2a wrote:
> >
> > > Hello,
> > >
> > > I would like to create a 3D mesh from a polyhedral domain, like in the
> > > example mesh_polyhedral_domain.cpp
> > >
> > > After I want make a cycle on each cell in order to transform each cell in
> > > a
> > > tetrahedron. The tetrahedron class would be used to calculate geometrical
> > > properties of the cells.
> > > from :
> > >
> > >
> > > http://www.cgal.org/Manual/3.2/doc_html/cgal_manual/Kernel_23_ref/Class_Tetrahedron_3.html
> > > CGAL::Tetrahedron_3<K> is constructed by
> > >  Tetrahedron_3<Kernel> t (       Point_3<Kernel> p0,
> > > Point_3<Kernel> p1,
> > > Point_3<Kernel> p2,
> > > Point_3<Kernel> p3);
> > >        introduces a tetrahedron t with vertices p0, p1, p2 and p3.
> > > So I modify the mesh_polyhedral_domain.cpp example with :
> > >
> > >
> > > -----------------------------------------------------------------------------------
> > >
> > > #include <CGAL/Tetrahedron_3.h>
> > >
> > > // Tetrahedron
> > > typedef CGAL::Tetrahedron_3<K> Tetrahedron_3;
> > > typedef K::Point_3 Point_3;
> > >
> > > int main()
> > > {
> > >  // Here create c3t3...
> > >
> > >  Point_3 p0,p1,p2,p3;
> > >  int mesh_cells_counter =0 ;
> > >   for(C3t3::Cell_iterator cit=c3t3.cells_begin(); cit != c3t3.cells_end();
> > > ++cit)     {
> > >                 if(c3t3.is_in_complex(cit))                     {
> > >                ++mesh_cells_counter;
> > >
> > >                        p0=(cit->vertex(0)->point());
> > >                        p1=(cit->vertex(1)->point());
> > > p2=(cit->vertex(2)->point());
> > >                        p3=(cit->vertex(3)->point());
> > >
> > >                        std::cout << (cit->vertex(1)->point()) <<
> > > std::endl;
> > >
> > >                        Tetrahedron_3 tetra (p0,p1,p2,p3);
> > >                                      }
> > >   }
> > >
> > > // std::cout << "Number of cells: " << mesh_cells_counter << std::endl;
> > >
> > >  return 0;
> > > }
> > >
> > > -----------------------------------------------------------------------------------------------------------------------
> > >
> > > But the compilation failed and return BOOST::STATIC_ASSERTION_FAILURE and
> > > I
> > > really don't understand the problem.
> > >
> > > In file included from /usr/include/CGAL/user_classes.h:48,
> > >                 from /usr/include/CGAL/squared_distance_2_1.h:30,
> > >                 from
> > > /usr/include/CGAL/Circle_2_Circle_2_intersection.h:30,
> > >                 from /usr/include/CGAL/intersection_2_3.h:29,
> > >                 from /usr/include/CGAL/intersection_2.h:31,
> > >                 from /usr/include/CGAL/intersections.h:29,
> > >                 from /usr/include/CGAL/AABB_intersections.h:20,
> > >                 from
> > > /home/ben/CGAL/CGAL-3.6/examples/BenWork/mesh_polyhedral_domain_ben.cpp:1:
> > > /usr/include/CGAL/Tetrahedron_3.h: In instantiation of
> > > ‘CGAL::Tetrahedron_3<K>’:
> > > /home/ben/CGAL/CGAL-3.6/examples/BenWork/mesh_polyhedral_domain_ben.cpp:90:
> > >  instantiated from here
> > > /usr/include/CGAL/Tetrahedron_3.h:42: error: invalid application of
> > > ‘sizeof’
> > > to incomplete type ‘boost::STATIC_ASSERTION_FAILURE<false>’ make[2]: ***
> > > [CMakeFiles/mesh_polyhedral_domain_ben.dir/mesh_polyhedral_domain_ben.o]
> > > Errore 1
> > > make[1]: *** [CMakeFiles/mesh_polyhedral_domain_ben.dir/all] Errore 2
> > >
> > >
> > > Thanks,
> > >
> > > Benjamin
> > Hi,
> >
> > Could you please try the following typedefs instead of yours (I don't know
> > if you want to use those or K::Tetrahedron_3 and K::Point_3 --
> > Tr::Geom_traits::Point_3 is actually a Weighted_point) ?
> >
> > typedef Tr::Geom_traits::Tetrahedron_3 Tetrahedron_3;
> > typedef Tr::Geom_traits::Point_3 Point_3;
> >
> >
> > And I would also like to provide you a tip :)
> > the following code is equivalent to yours.
> >
> > -----------
> >
> > int mesh_cells_counter =0 ;
> > for(C3t3::Cell_iterator cit=c3t3.cells_begin(); cit != c3t3.cells_end();
> >    ++cit)
> > {
> >  // cit is in c3t3 by definition
> >  ++mesh_cells_counter;
> >  Tetrahedron_3 t = c3t3.triangulation().tetrahedron(cit);
> > }
> > assert (mesh_cells_counter == c3t3.number_of_cells());
> > -----------
> >
> >
> > Best,
> > Stéphane.
> >
> > --
> > Stephane Tayeb
> > Software engineer - INRIA Sophia Antipolis
> > Geometrica Project-Team
> >
> >
> > --
> > You are currently subscribed to cgal-discuss.
> > To unsubscribe or access the archives, go to
> > https://lists-sop.inria.fr/wws/info/cgal-discuss


--
Stephane Tayeb
Software engineer - INRIA Sophia Antipolis
Geometrica Project-Team