[MOAB-dev] Vertex-vertex adjacencies in iMesh?

[James Porter]

Should iMesh return an error when you ask for the vertices adjacent to
another vertex? As I understand it (not that I can find a citation), the
iMesh spec says that vertices aren't adjacent to themselves, but does it
also require that the functions return errors? It seems like it would be
better to return no adjacencies instead.

This ends up being a problem for MeshKit (specifically in CopyMesh and
ExtrudeMesh) because we need to get the adjacent vertices, but if the
set or array you pass in contains vertices, it will fail. The end result
is that the user has to create a set or array without the vertices,
which is bothersome and slower than it needs to be.

It also presents more problems for ExtrudeMesh, since it's conceivable
that you'd want to pass in vertices as a way of telling MeshKit that you
want to extrude vertices into line segments.*

There may also be issues with copy/expand/extrude sets (should the
vertices get put in them if they weren't explicitly passed in?), but I'm
not sure if that's important in practice.

- Jim

* This would require a vertex to be "adjacent" to itself, which I think
is sensible anyway, but that's another story.