CGAL users discussion list

["Fred Fred" <>]

Hello,

> From: Mariette Yvinec 
> <>
> Reply-To: 
>
> To: 
>
> Subject: Re: [cgal-discuss] How to build a polyhedron?
> Date: Tue, 17 Apr 2007 18:52:14 +0200
>
> Fred Fred wrote:
>
> > Basic question but soooo complicated to find a way to do it with CGAL 
> > documentation! I have been surfing in the doc for 3 hours and still have 
> > not reached it. Actually I have manage to create a triangulation of a 
> > terrain and now I would like to refine it. Unfortunately it seems that it 
> > is necessary to convert the triangulation to a polyhedron, so I would have 
> > expected a conversion method so as to create a polyhedron from my 
> > traingulation but either it does not exist or I did not find it.
> > So could anyone tell me how I could create a polyhedron from my 
> > triangulation in less than 3 hours?
> > Regards.
> >
> > _________________________________________________________________
> > Découvrez le Blog heroic Fantaisy d'Eragon! 
> > http://eragon-heroic-fantasy.spaces.live.com/
> I don't see why you need to convert the triangulation into a polyhedron
> to be able to refine your terrain.
> See the example of terrain in the user manuel of Triangulation_2 : 
> insertion are performed.

I did but only found the necessary material for reimplementing the 
subdivision (vertex insertion and so). But since different subdivision 
schemes have already been implemented in the librayry (eg loop scheme) I 
would have expected that they could be reused for my problem. But, as far as 
I did not miss anything, all the subdivision algorithms in CGAL deal with 
polyhedrons and not triangulations, right?
Another issue: it is very difficult to cope with the so numerous types 
defined in the library, particularly I made the following declarations:
 struct Kdelaunay : CGAL::Exact_predicates_inexact_constructions_kernel {};
 typedef CGAL::Triangulation_euclidean_traits_xy_3<Kdelaunay> Gt;
 typedef CGAL::Delaunay_triangulation_2<Gt> Delaunay;
 Delaunay del;
And now I would like to copy the triangulation so as to insert new verticies 
but not under Delaunay constraints (I want to build a multiresolution 
model), so I wrote:
 typedef CGAL::Triangulation_2<Gt> TDS;
but nor:
 TDS tr(del);
neither:
 TDS tr(del.geom_traits(), del.tds());
works, so probably there are some lacks in my C++ templates knowledge but 
HOW TO GET A COPY OF THE TRIANGULATION created by Delaunay??
thanks in advance for your help.

_________________________________________________________________
Windows Live Spaces : créez votre blog à votre image ! 
http://www.windowslive.fr/spaces