CGAL users discussion list

[KHartmann <>]

Thank you Sebastien.

Using CGAL::Exact_predicates_exact_constructions_kernel I can now read in
the s.off file that I mentioned.

I have a few follow-up questions regarding the geometric requirements of the
OFF file when performing a Polyhedron_3 OFF file read.

//// Begin your code example //////////
std::ifstream file("myoff.off"); 
Polyhedron_3<Kernel> P; 
file >> P; 
Nef_polyhedron_3<Kernel> nef(P); 
//// End your code example //////

1) Do the vertices for each polygon need to be listed in the
counter-clockwise direction (I'm seeing evidence that this might be the
case.)

2) Must the OFF file contain only one polyhedron?  (I'm seeing indications
that this too is a requirement.)

3) Is there any way to describe a polyhedron which contains through-holes in
an OFF file?  Or must I describe two OFF files, and boolean subtract one
from the other?  (I've attached a sample object.) 

<http://cgal-discuss.949826.n4.nabble.com/file/n4660590/BoxWithHole.png> 

4) If number 3) can't be done with an OFF file, is there a quicker way to
create a Nef_polyhedon_3 without using OFF?  Imagine my goal is to create a
rectangular plate with hundreds of holes in it.  I would like to just supply
my well-defined data to CGAL and construct a NEF.  Is there any way for me
to construct such an object without creating hundreds of individual nef
polyhedrons and using boolean operations to achieve the final goal?  Boolean
operations in such cases seems to be unnecessarily time consuming.  (And
OFF_to_nef_3 is too time consuming as mentioned at the beginning of this
thread.)

5) Is there any place in the documentation that describes the geometric
requirements of an OFF file which is to be used with Polyhedron_3 read-in?



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