CGAL users discussion list

[Sebastien Loriot <>]

On 7/22/22 18:23, KL ( via cgal-discuss Mailing 
List) wrote:
> Hi,
> Straight to the goal, the questions are related to the image in that link:
> https://pasteboard.co/HiStqY1Qe86t.jpg
> Context: I have two polygons, one red, one, which is its asymmetric 
> inset, blue.
> 1) I use the skeleton and offset package to get the inward polygon, 
> which works just fine. But all the sides have the same offset.
> In the image, you can see I need one side with no offset.
> -> How do I do that?

There is nothing in the API do that. I'm not sure it is even correctly
defined in general. Maybe you can clip the output if the edge is somehow 
on the "border".

> 2) Then, I want to triangulate the red and blue zones (they can be 
> considered the domain of interest).
> But the issue is that I don't know better than using a point set with 
> the CGAL::advancing_front_surface_reconstruction function.
> Pretty sure that's the root of my problem.
> Code:
>                 typedef std::array <std::size_t, 3> Facet; // Triple of 
> indices
>                  std::vector <Facet> facets;
>                  CGAL::advancing_front_surface_reconstruction( 
> points.points().begin(),
>                                                                
> points.points().end(),
>                                                                
> std::back_inserter( facets ) );
> I would like the triangulation to obey that I am not interested by 
> connecting lines which go outside the polygons.
> On the image, the green line is the reduced example of what I am talking 
> about, others undesirable ones exist.
> I am sure that it is because I miss an option.
> -> How do I force the triangulation inside the polygons only?

You should try to adapt the following example:
https://doc.cgal.org/latest/Triangulation_2/Triangulation_2_2polygon_triangulation_8cpp-example.html
to your need.

Best,

Sebastien.

> Thanks!
> --
> MKL
>
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