CGAL users discussion list

["Jens K. Becker" <>]

Ah-haha, how embarrassing....

yes, a multimap would certainly be the thing to use. Why didn't I think of it?
Much simpler and does exactly what I need.

Thanks, very much appreciated!

Jens
--
Dr. J.K. Becker
University of Tuebingen - Institute for Geoscience
Sigwartst. 10 - 72076 Tuebingen (Germany)
Tel.: ++49 7071 29 73139   Fax: +49 7071 5059
web: http://www.jkbecker.de


Quoting Andreas Fabri 
<>:

> Hi Jens,
>
> A std::multimap<Point_3, Polyhedron::Vertex_handle> should do it.
>
> You traverse all vertices of all polyhedra and insert the point and
> vertex in the map.
>
> When you want to change the coordinates of one point, the multimap
> will give you all vertices that have a copy.
>
> A completely differnent approach miht be not to store points in
> the polyhedron, but pointers to one point, So when you change the
> coordinated of this point, you have changed it for all vertices.
> But that needs programming some point proxy.
>
> andreas
>
>
> Jens K. Becker wrote:
> > Hi all,
> >
> > I am a bit at a loss with the concepts of range and segment trees 
> > and how to use
> > them. Therefore, I guess it is easiest to try and explain what I 
> > want to do...
> >
> > I have a number of polyhedra that do not overlap and there are no 
> > gaps between
> > them. I triangulate them so that the different triangles making up the
> > polyhedra are shared between 2 (or more) neighbouring polyhedra. This means
> > that each point (vertex) is in the list at least twice, but can be 
> > there more
> > often (in case 3 or more polyhedra share a point). What I want to do 
> > is to be
> > able to quickly change the coordinates of a point (vertex). The brute-force
> > method would be to go through the list of all points of all polyhedra, check
> > the coordinates and change them if necessary. This would take a long 
> > time. It
> > would be better to have a tree structure so that with a single query I would
> > find all points at once. The problem is that after changing the 
> > coordinates of
> > these points, they have to be reinserted into the tree and the old ones
> > deleted. And I cant figure out if CGAl can do that.
> > I have written my own template to do this and it works, but bugs a 
> > lot due to
> > memory leaks (might be related to GMPZ though, not sure and really hard to
> > debug). So I am thinking about using an already made tree structure 
> > or so from
> > CGAL. Is that possible? Can I find, delete and reinsert elements 
> > (leafs) into
> > an already existing tree in CGAL?
> >
> > Thanks for your help,
> >
> > Jens Becker
>
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