CGAL users discussion list

[Bartłomiej Siwek <>]

Hello everyone,

First of all I would like to say I'm new to CGAL and this mailing list so 
literally every bit of knowledge may help :)

Second of all I would like to ask about the usage of custom vertex attributes 
and boundary markers with  3D Mesh Generation (Mesh_3) package.
I'll start by providing some context. I would like to use the D Mesh 
Generation (Mesh_3) package to generate a tetrahedron mesh to be used with 
Finite Element Method.
The problem I'm working on suggests following data flow:
1) The problem domain will be modeled in some 3d modeling application and 
saved to a file as a polyhedral mesh (format of the file still has to be 
chosen but there are no constraints on this). The domain will have a 
subdomain (that I guess will be a polyhedral mesh itself) that is contained 
within the main domain. The boundary of the main domain has some "hot spots" 
that I need to designate during this first step - for this I would like to 
"mark" the triangles that constitute the part of this boundary with some 
boundary marker.
2) The domain and subdomain should now be used to genarate a tetrahedron mesh
3) The mesh will be edited again in order to assign some vertex attributes - 
the diffusion tensors, initial densities etc. to the vertices
4) The mesh may undergo one or more refinements depending on the FEM 
computation results

The problem I haven't found an obvious answer to is how to include the 
boundary markers and vertex attributes in such a way that the propagate as 
follows:
- For boundary markers, if a marked triangle is split into several triangles 
each new one will be marked as well.
- For vertex attributes, the new vertices generated should have the 
attributes interpolated linearly from vertices used to generate the new one.

How can one achieve above behavior?
Let me note that it doesn't have to be direct. If after creating a mesh/doing 
refinement I can get a mapping from vertices of the old mesh to the same 
vertices in new mesh I'll be more than happy to compute the 
attributes/markers myself.

Best Regards,
Bartłomiej Siwek