[Gmsh] Missing surface label and duplicate surfaces

[Christophe Geuzaine]

> On 21 Jan 2019, at 10:13, Alessandro Vicini <alessandro.vicini at sitael.com> wrote:
> 
> 
> With reference to the attached contour.geo file (including background.geo which is merged into it), gmsh does not show surface #14: the label is not shown, and also its graphic representation as "cross" is not visible. 

The surface is very "thin", so no start/end point for the cross could be computed. But the surface is correct: choose e.g. a solid or wirefreme representation to visualize it. (You could open an issue on our gitlab so that we remember to enhance the "cross" drawing code, e.g. to at least include one point?).

> Moreover, when I generate the volume some of the surfaces are duplicated; this gives me troubles with my own pre-processing of the msh file, is there some way to avoid it? Thank you.
> 

By default we ask OpenCASCADE to automatically fix the orientation of the surfaces making up a volume defined "by hand". This can lead to duplicate entities. In your case, just put at the end of your file

Geometry.OCCAutoFix = 0;
Surface Loop(2) = {6, 5, 4, 3, 2, 15, 14, 13, 12, 11, 10, 9, 16, 17, 18, 7};
Volume(1) = {2};

and you should be OK.

Christophe




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