CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On this page:

http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Triangulation_3_ref/Class_Triangulation_3.html

you have the documentation of the function incident_cells
that you can use like this:

typedef CGAL::Delaunay_triangulation_3 DT;
DT dt;

std::list<DT::Cell_handle> infinite_cells;
dt.incident_cells(dt.infinite_vertex(),std::back_inserter(infinite_cells));

Then for each Cell_handle c in infinite_cells,
c.neighbor(c.index(dt.infinite_vertex())) is one of the tetrahedra
you are looking for.

Sebastien.


On 01/23/2012 08:59 PM, Adam Hopkins wrote:
> Hi There:
>
> Could anyone give me suggestions or an example code to solve my problem
> which is described below?
> Thanks and waiting for help
>
> A.
>
> On Mon, Jan 23, 2012 at 4:48 PM, Adam Hopkins 
> <
> <mailto:>>
>  wrote:
>
>     Hi Andreas:
>
>     Thank you for your answer and your solutions seem perfect. But,
>     could you send me a short code to see the best way to do this?
>     because there are different iterators (all_cells_iterator,
>     finite_cells_iterator, etc) and I do not know how I can implement
>     your solution (what are the involved methods and what kind of
>     elements do I need to iterate?). While, on the other hand I also
>     need to know which are the vertexs of the external faces. Will be
>     perfect if you can send me an example for solve these problems.
>
>     thanks a lot
>     A.
>
>     On Mon, Jan 23, 2012 at 4:03 PM, Andreas Fabri
>     
> <
>     
> <mailto:>>
>  wrote:
>
>         On 23/01/2012 15:39, Adam Hopkins wrote:
>
>             Hi All:
>
>             I have a set of points in the three dimentional space, where a
>             triangulation using CGAL library was computed. How Can I
>             know which are
>             the most external tetrahedrons? is to say, the tetrahedrons
>             which have
>             at least one external face. Are there functions or any form
>             to know
>             that? Is possible to iterate only these kind of elements?
>
>             thanks
>             A.
>
>
>         Hi Adam,
>
>         For all cells incident to the infinite vertex,
>         take the cell opposite to the infinite vertex.
>
>         andreas
>
>         --
>         Andreas Fabri, PhD
>         Chief Officer, GeometryFactory
>         Editor, The CGAL Project
>
>         phone: +33.492.954.912 <tel:%2B33.492.954.912>    skype:
>         andreas.fabri
>
>         --
>         You are currently subscribed to cgal-discuss.
>         To unsubscribe or access the archives, go to
>         https://lists-sop.inria.fr/__wws/info/cgal-discuss
>         <https://lists-sop.inria.fr/wws/info/cgal-discuss>