CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

If you have been able to build a Polyhedron or a Surface_mesh it means
that it is not a polygon soup.

I guess you do something different than just loading the two files
posted. If you have a minimal example showing the pb it would help
to tell you exactly what the pb is.

Sebastien.

On 12/13/2017 03:33 PM, Sean Hardesty wrote:
> I was able to compile the polyhedron demo and duplicate the results you 
> described. However, I don't understand how I would test for this in my 
> own program. I generated the .off files I sent from CGAL::Surface_mesh - 
> how do I check whether such an object is a polygon soup (as is done in 
> the demo)?
>
> All of the following look okay:
>
> mesh.is_valid() = 1
> CGAL::Polygon_mesh_processing::does_bound_a_volume(mesh) = 1
> CGAL::Polygon_mesh_processing::does_self_intersect(mesh) = 0
> CGAL::Polygon_mesh_processing::is_outward_oriented(mesh) = 1
> CGAL::is_closed(mesh) = 1
>
> I wanted to try something from the polygon soup example, like this
>
> CGAL::Polygon_mesh_processing::is_polygon_soup_a_polygon_mesh
>
> but I haven't been able to figure out how to call that on a 
> CGAL::Surface_mesh object.
>
>      Thanks,
>      Sean Hardesty
>
> On Wed, Dec 6, 2017 at 2:24 AM, Sebastien Loriot (GeometryFactory) 
> < <mailto:>> wrote:
>
>     When I open you files in the CGAL polyhedron demo, it is telling me that
>     your meshes are polygon soups (meaning you have non-manifold edges).
>     If I duplicate those edges to make it a self-intersecting surface
>     I have the following set of intersecting faces.
>
>     Sebastien.
>
>     On 12/05/2017 05:22 PM, Sean Hardesty wrote:
>
>         I have a collection of meshes that overlap slightly, so I am
>         going through a loop removing overlapping pieces. It works for a
>         while, but eventually I run into trouble. I am calling
>         PMP::corefine_and_compute_difference(CGAL 4.11) on a pair of
>         meshes that satisfy
>
>         !CGAL::Polygon_mesh_processing::does_self_intersect
>         CGAL::Polygon_mesh_processing::does_bound_a_volume
>
>         and I get the following:
>
>         terminate called after throwing an instance of
>         'CGAL::Assertion_exception'
>             what(): CGAL ERROR: assertion violation!
>         Expr: hedge!=start
>         File:
>         
> /usr/local/include/CGAL/Polygon_mesh_processing/internal/Corefinement/Visitor.h
>         Line: 663
>         Aborted (core dumped)
>
>         They are fairly small, so I wrote them to .off format and
>         attached them to this message. I am aware from your
>         documentation pages that there can be problems with sequential
>         boolean operations, so I am using the kernel with exact
>         predicates and exact constructions. Maybe the precision in the
>         .off format is inadequate to diagnose the problem. I would be
>         grateful for any help that can be provided.
>
>               Sincerely,
>               Sean Hardesty
>
>
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