[Gmsh] Error when using a lot of boolean operations and gmsh crashing in complex tree-like geometry

[Christophe Geuzaine]

> On 9 Apr 2019, at 21:00, Timo Koch <timo.koch at iws.uni-stuttgart.de> wrote:
> 
> Dear Gmsh community,
> 
> like in this previous post on this mailing list (http://onelab.info/pipermail/gmsh/2017/011809.html),
> 
> I have a tree-like geometry, consisting of a union cylinders and spheres, and I'd like to cut it out of a box.
> 
> The problem mentioned in this post in 2017 still seems to persist in Gmsh 4.2.3.
> 
> I've been trying to subtract a lot of cylinders and spheres from a box geometry. It works for a small amount of cylinders but refuses to work for many geometries. The error message is simply 
> 
> Error   : Intersection operation cannot be performed
> Error   : 'tree.geo', line 3480 : Could not apply boolean operator
> 
> I attached the geo file. Any idea what the problem is? Is there some kind of internal limit on how many geometry objects can participate in boolean operations?
> 

It's a limitation of OpenCASCADE, which indeed still fails to perform boolean operations on some complex geometries.

I encourage you to export the geometry in the native OpenCASCADE .brep format without the boolean operation (i.e. add Save "file.brep"; before the boolean operation in the .geo file) and file a bug report with the OpenCASCADE folks describing what you want to do.

Christophe



> Thank you for your help
> 
> Timo
> 
> 
> 
> -- 
> _______________________________________________________________
> 
> Timo Koch                              phone: +49 711 685 64676
> IWS, Universität Stuttgart             fax:   +49 711 685 60430
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> 
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine