CGAL users discussion list

[Philipp Moeller <>]

Jonas Wallin 
<>
 writes:

> Hello,
>
> Yes I have look at those pages for 2D but a few things are unclear to me.
> It says
> "the indices of its vertices and the non combinatorial information (if any)
> in this face"
> what I don't understand is what is the non combinatorial information?

The points of the vertex, for example. (As far as I can see this is the
only things that is currently written to the stream.)

>
> Because if I have a triangulation with say indexes on the vertices and I
> would like to have that information passed into
> cgal through the operator <<(). This seems possible if I interpret the
> documentation correctly but to me it is not clear how to do it.

Can you just read the file in yourself and use insert to add vertices to
the triangulation?

>
> If I would known that the vertices are stored in the same order that they
> are read from the file it would be easy to have a separate
> file with the data read into the program. But I don't see it written any
> where that this is the case and esthetically that solution dosn't look good
> to me.
>
> mvh
> Jonas
>
> Hej Jonas,
>>
>> That makes sense. So, did you have a look at these pages yet?
>> for 3D:
>> http://www.cgal.org/Manual/**latest/doc_html/cgal_manual/**
>> Triangulation_3_ref/Class_**Triangulation_3.html<http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Triangulation_3_ref/Class_Triangulation_3.html>
>> for 2D:
>> http://www.cgal.org/Manual/**latest/doc_html/cgal_manual/**
>> Triangulation_2_ref/Class_**Triangulation_2.html<http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Triangulation_2_ref/Class_Triangulation_2.html>
>> (from your mails I couldn't tell whether you are working in 2D or 3D,
>> although I suspect 2D)
>>
>> On both of these pages at the very end you see that both operator<<() and
>> operator>>() are overloaded in CGAL to act on a triangulation and the
>> format is explicitly explained. Since you already have the full
>> triangulation in some format, I'm guessing it shouldn't be to hard too
>> convert that into 'CGAL-formatting', allowing you to directly read the
>> triangulation into CGAL triangulation object using the extraction operator,
>> operator>>().
>>
>> Sincerely,
>> Jakob
>>
>>
>>>    Hej Jonas,
>>>
>>>    Maybe a bit silly.....if you have the tessellation already, why use
>>> CGAL to recalculate the same tessellation?
>>>
>>>    Greetsz, Jakob
>>>
>>>    [..]
>>>
>>>
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-- 
Philipp Moeller
GeometryFactory