CGAL users discussion list

[Peter Hachenberger <>]

Dear Wayne,

the file format is not documented, because I was not satisfied with it
and changed it sometimes. Now, it would be a good moment to start
documenting it - apart from some redundant geometric entries, it is
stable. If you want to know how it works, you must know pretty much
about the structure of our data structure. Therefore I advice you to
read the respective chapters of my SPM paper or my CGTA paper, which are
both available at my homepage

http://www.win.tue.nl/%7Ephachenb/publications.html

Then you can look up the print/read functions in SNC_io_parser to
understand the file format.

The example you are searching for can be found at 
examples/Nef_3/. If you want separate handling of the outer shells and
the shells of the holes, then you must write two different visitor
classes. Then call the function visit_shell_objects first for all outer
shells passing the first visitor, and then for all inner shells passing
the second visitor. Note that the iterator range [c->shells_begin(),
c->shells_end() ) gives you all shells of a volume; the outer shell is
always the first.

Peter

On Mon, 2007-12-10 at 08:21 +0100, 

 wrote:
> All:
> 
> I've just downloaded CGAL and I am totally impressed
> with the amount of functionality provided.
> 
> My interest is in doing some 3D Boolean operations
> and the Nef3 Polyhedra look like it will be more than
> adequate for my purposes.
> 
> I modified the Nef3 stack demo to write out .nef3
> files and I was wondering if the file format is
> documented anywhere?
> 
> If not, is there a code example that iterates over
> all of the exterior facets and provide both the
> exterior polygon boundary and the any internal
> polygon hole boundaries?  (Please excuse my use
> of terminology, I am an electrical engineer by
> training, so I frequently use the incorrect words
> when I am in the mathematics/geometry domain.)
> 
> Any help would be greatly appreciated.
> 
> -Wayne