[Gmsh] Orientation of normals for compound surfaces

[Christophe Geuzaine]

> On 1 Oct 2019, at 14:49, Rick <rickgreen16 at protonmail.com> wrote:
> 
> I am trying to mesh volumes from triangulated surface meshes using the "Compound Surface" construct to identify patches that should be parametrized and meshed together. I have ensured that the surface normals are pointing outwards according to the right hand rule but always seem to get warnings of the type
> 
> "Warning: Could not orient normal of surface ##"
> 
> If I permute the edge ordering for the "Curve Loops" I can suppress some of the warnings, but not all, and it is not clear why one permutation is allowed. If I remove the "Compound Surfaces" I don't have this issue, but also the re-parametrization is lost.
> 
> I have not been able to find any definitive documentation on this so I would be very appreciative if anyone could clear up how to get the normal orientations right for compound surfaces (I have attached a minimal unit cube geo file which illustrates the issue).

Could you try a recent snapshot (future Gmsh 4.5)? This should be fixed.

Christophe

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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine