CGAL users discussion list

[Stefan Witzel <>]

Am Mi., 19. Juni 2019 um 20:31 Uhr schrieb Monique Teillaud
<>:
> ----- Le 19 Juin 19, à 3:16, Stefan Witzel 
> 
>  a écrit :
> > Am Di., 18. Juni 2019 um 19:54 Uhr schrieb Monique Teillaud
> > <>:
> > So to do things in the cgal spirit one should probably represent
> > polygons by their vertices and only create the hyperbolic segments
> > when drawing the polygon. In that situation one would then have the
> > vertices as well as the segments available and could sort out the
> > right orientation.
>
> If I understand correctly, this goes along the same lines as what I 
> proposed in my previous email:
> * use circulators to get the combinatorial structure (the polygon is left 
> implicit)
> * use segments as (non-oriented) geometric objects.

Except that you suggested to iterate over edges and take their duals
which are hyperbolic segments and therefore not combinatorial objects
as you would say. With that approach one does not get the circular
order of the vertices. This was the very first thing I tried and it
took almost a day to figure out why it's not working.

> > Just to make sure: this cgal convention on counterclockwise
> > orientation of circular arcs is just an internal convention, not
> > guaranteed behavior, correct? So if I have a hyperbolic segment I
> > really know nothing about the role of source() and target()?
>
> If I am not mistaken, source() and target() are not even mentioned in the 
> manual.

Yes, well, I still haven't gotten to grips with the manual.

Best,
Stefan