CGAL users discussion list

[Andreas Fabri <>]

Hyungon Kim wrote:
> Hi Andreas,
>
> Thanks Andres. I suppose that CGAL has a direct method to do this.
> I tried Arrangement of CGAL to convert complex polygon in Polygon_2 to 
> simple polygon in Polygon_with_holes.
> However, Arrangement is unlike converting all kind of complex polygons 
> to simple polygon well.
> Should I write a method like yours to do this task?

Hi Hyungon Kim,

We haven't incorporated the piece of code in CGAL. The arrangement
expects simple polygons, that is edges must not intersect.

What is in CGAL is the conversion in the other direction,
that is you can obtain a (not simple polygon) from a polygon
with hole. It just inserts vertical edges where necessary.
http://www.cgal.org/Manual/3.4/doc_html/cgal_manual/Boolean_set_operations_2_ref/Function_connect_holes.html

best regards,

andreas

> Thanks,
> Hyungon Kim
>
> Andreas Fabri wrote:
> > Hello,
> >
> > For simple cases  where points p,q appear later in the sequence
> > in reverse order q,p  the attached file can split it.
> >
> > It will not work, if in your example the point 10,10 wasn't there twice.
> >
> > Best regards,
> >
> > andreas
> >
> >
> >
> >  wrote:
> > > Dear All,
> > >
> > > Hi. I am a new learner in CGAL. I have tried to make a sample program 
> > > to do
> > > boolean operation on 2D polygons. My problem is how to make
> > > Polygon_with_holes_2 from input Polygon_2 with holes (complex 
> > > polygon) before
> > > boolean operation. For example, points of input Polygon_2 are
> > >  (0,0) (10,0) (10,10) (10,20) (20,20) (20,10) (10,10) (10,0) (30,0) 
> > > (30,30)
> > > (0,30)
> > > Is there a CGAL package to make Polygon_with_holes from this complex 
> > > polygon?
> > >
> > > Best Regards,
> > > Hyungon Kim