CGAL users discussion list

[Sebastien Loriot <>]

Sorry, I missed one part of your code.
Digging a bit, I found out that there is a bug.
I will post updates in the following ticket:
https://github.com/CGAL/cgal/issues/6777

Thanks for the report!

Sebastien.

On 7/28/22 12:22, Marco Feder ( via cgal-discuss Mailing 
List) wrote:
> I’m sorry but I’m not quite sure I understood what you meant. Are you 
> saying that the /std::vector<Point_3>/ return type doesn’t cover the 
> case when the intersection is a polygon?
>
> Thanks,
> Marco
>
> > On 28 Jul 2022, at 08:27, Sebastien Loriot < 
> > <>> wrote:
> >
> > For sure but if you get let say a quad you need to add its area.
> >
> > Do you seen what I mean?
> >
> > Best,
> >
> > Sebastien.
> >
> > On 7/26/22 18:08, Marco Feder ( 
> > <> via cgal-discuss Mailing List) wrote:
> > > Dear Sebastien,
> > > That is precisely what I did in the GitHub gist I linked in my post, 
> > > isn’t it ?
> > > Best,
> > > Marco
> > > > On 26 Jul 2022, at 17:08, Sebastien Loriot < 
> > > > <>> wrote:
> > > >
> > > > The intersecton of a triangle with a tet is not always a triangle, it is
> > > > a polygon,
> > > >
> > > > Doc says:
> > > > |Type1  | Type2 |Return Type: T...|
> > > > |Triangle_3 Tetrahedron_3 | Point_3, or Segment_3, or Triangle_3, or 
> > > > std::vector < Point_3 > |
> > > >
> > > > https://doc.cgal.org/latest/Kernel_23/group__intersection__linear__grp.html 
> > > > <https://doc.cgal.org/latest/Kernel_23/group__intersection__linear__grp.html>
> > > >
> > > >
> > > > So it is most likely you miss some polygons.
> > > >
> > > > Best,
> > > >
> > > > Sebastien.
> > > >
> > > > On 7/20/22 10:44, Marco Feder ( via cgal-discuss 
> > > > Mailing List) wrote:
> > > > > Dear all,
> > > > > I have two cubes (they’re coming from two cells of a 3D finite 
> > > > > element mesh) and a square (a 2D object) between the two, 
> > > > > intersecting both of them. I triangulated each cube with a 
> > > > > Triangulation_3, and the square with a Delaunay_triangulation_2.
> > > > > To compute the intersection of the square with the first cube, I do 
> > > > > the following: I loop over all tets of the triangulated cube, and 
> > > > > for each Tetrahedron I compute the intersection with a Triangle_3 
> > > > > coming from the triangulated 2D square. Oftentimes I have correct 
> > > > > results, but in some scenarios I observe inaccurate results.
> > > > > For instance: for each cube, I computed the area of the part of 
> > > > > square inside it. The sum of these two areas should be precisely 
> > > > > equal to the area of the square (it is exactly *0.136900*), but 
> > > > > it’s not. In particular, the first area is *0.0237738*, and the 
> > > > > second *0.0948123. *Then the sum is *not 0.136900.*
> > > > > The following GitHub gist shows this: 
> > > > > https://gist.github.com/fdrmrc/49f397a5f72a7a00b1dfb992ab7babe1 
> > > > > <https://gist.github.com/fdrmrc/49f397a5f72a7a00b1dfb992ab7babe1> . 
> > > > > The output is the area of the intersection of the square with the 
> > > > > second cube. To get the first area, change at line 52 
> > > > > /pts_second_hex /with /pts_first_hex./
> > > > > I can’t spot what is going wrong here.
> > > > > Best,
> > > > > Marco
> > > > > --
> > > > > You are currently subscribed to cgal-discuss.
> > > > > To unsubscribe or access the archives, go to
> > > > > https://sympa.inria.fr/sympa/info/cgal-discuss
> > > >
> > > > --
> > > > You are currently subscribed to cgal-discuss.
> > > > To unsubscribe or access the archives, go to
> > > > https://sympa.inria.fr/sympa/info/cgal-discuss
> >
> > --
> > You are currently subscribed to cgal-discuss.
> > To unsubscribe or access the archives, go to
> > https://sympa.inria.fr/sympa/info/cgal-discuss 
> > <https://sympa.inria.fr/sympa/info/cgal-discuss>
>
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to
> https://sympa.inria.fr/sympa/info/cgal-discuss