CGAL users discussion list

["Laurent Rineau (GeometryFactory)" <>]

On vendredi 10 juin 2011 18:53:57 Michel Audette wrote:
> Dear CGAL developers,
> 
> as you may recall, I am pursuing tetrahedral meshing that is faithful
> to boundary features, which is now supported in 3.8. The examples
> given suggest a an implicit function whose boundary points comprise a
> polyline, which in turn is used as the features of the mesh domain,
> and a polygonal surface mesh whose angular features are detected
> automatically. The problem that I have is sort of in-between. I would
> like to input an anatomical polygonal surface whose boundary must be
> adhered to faithfully, but which also does not exhibit hard corners
> the way that your fandisk example does, and it seems that the
> detect_features() function does not result in the correct boundary
> being maintained. I would consider populating a polyline, like the
> other example, but I'm not dealing with an implicit function here. Is
> it possible to instantiate the polyline approach with something other
> than the an implicit function, or conversely get the input polygonal
> surface to be espoused completely with the detect_features method?

Dear Michel,

In the documentation of of the class template 
Polyhedral_mesh_domain_with_features_3 (see [1]), used in the fandisk 
example, 
you can see the function

  domain.detect_features()

But that class template also derives from the class template  
Mesh_domain_with_polyline_features_3 (see [2]), and that means you can also 
do:

  domain.add_features(polylines.begin(), polylines.end());

like it is done in the implicit function example. I think that is what you 
want. For a polyhedron domain, detect_features() is just a shortcut that 
computes a set of polylines by detecting sharp edges of the polyhedron, and 
then passes that set of polylines to add_feature(...).

[1] 
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Mesh_3_ref/Class_Polyhedral_mesh_domain_with_features_3.html
[2] 
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Mesh_3_ref/Class_Mesh_domain_with_polyline_features_3.html

> PS: I think that the output to vtk is working. I was able to visualize
> a result with Paraview.

Great!

-- 
Laurent Rineau, PhD
R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
Release Manager of the CGAL Project       http://www.cgal.org/