[Gmsh] Gmsh API Licensing

[Christophe Geuzaine]

> On 23 Oct 2019, at 19:38, Juan Sanchez <juan.e.sanchez at gmail.com> wrote:
> 
> Hello Christophe,
> 
> Could you please elaborate on the current state of TetGen in Gmsh?  You say it is no longer being linked.  Is it still an available 3d meshing algorithm in Gmsh?

No. Old versions of Gmsh actually didn't use the Tetgen mesh generation algorithm, only the boundary recovery code. This code has now been relicensed directly for integration in the Gmsh kernel (see Mesh/tetgenBR.*), under the Gmsh license.

>  How does this work?  There is no mention of this in the changelog, and the tetgen license exception is still in the license.

We left the exception for older versions of Gmsh, but we can indeed remove it for Gmsh 4 and up. (The ChangeLog could indeed have been more explicit. For version 4.0.0 : "new 3D tetrahedralization algorithm as
default".)

> 
> What are the available 3D algorithms?

The default algorithm is Gmsh's "Delaunay", which supports all the meshing features (mesh size fields, hybrid meshes, embedded entities). The new algorithm in development is "HXT", which is much faster (and parallelized), but does not yet support advanced features. We also provide access to Netgen ("Frontal"), as well as limited support for MMG3D (for 3D aniso meshes).

Christophe


> 
> Regards,
> 
> Juan
> 
> 
> On Wed, Oct 23, 2019 at 12:12 PM Christophe Geuzaine <cgeuzaine at uliege.be> wrote:
> 
> 
> > On 23 Oct 2019, at 15:42, Juan Sanchez <juan.e.sanchez at gmail.com> wrote:
> > 
> > If you use:
> > https://github.com/nschloe/pygmsh 
> > 
> > which is a MIT-licensed library, I would argue that your software could remain closed source.  pygmsh provides a means to generates .geo scripts, which are then interpreted by Gmsh, so no dynamic linking is involved.
> > 
> 
> Indeed.
> 
> > Of course, I would recommend talking to your legal department concerning your strategy.  I would be most concerned about the implications of using the AGPL when Gmsh dynamically links against the TetGen library.
> > 
> 
> Note that since version 4 Gmsh does not link to Tetgen anymore.
> 
> Christophe
> 
> 
> > Regards,
> > 
> > Juan
> >  
> > 
> > On Tue, Oct 22, 2019 at 1:51 PM Jean-François Remacle <jean-francois.remacle at uclouvain.be> wrote:
> > 
> > 
> >> Le 21 oct. 2019 à 22:11, Niloufar <faghihi.niloufar at gmail.com> a écrit :
> >> 
> >> Hi,
> >> 
> >> I am a new user of Gmsh and I have a question regarding its licensing. I was wondering whether the Gmsh API is also under the GPL license meaning that I can not use the Gmsh API in a closed-source Python code. Is that right?
> >> 
> > 
> > Question : If a programming language interpreter has a license that is incompatible with the GPL, can I run GPL-covered programs on it?
> > 
> > Answer : When the interpreter just interprets a language, the answer is yes. The interpreted program, to the interpreter, is just data; the GPL doesn't restrict what tools you process the program with.
> > 
> > However, when the interpreter is extended to provide “bindings” to other facilities (often, but not necessarily, libraries), the interpreted program is effectively linked to the facilities it uses through these bindings. The JNI or Java Native Interface is an example of such a facility; libraries that are accessed in this way are linked dynamically with the Java programs that call them.
> > 
> > So if these facilities are released under a GPL-incompatible license, the situation is like linking in any other way with a GPL-incompatible library.
> > 
> > JF
> > 
> >> Thank you,
> >> Niloufar
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> > 
> > ------------------------------------------------------------------
> > Prof. Jean-Francois Remacle
> > Universite catholique de Louvain (UCL)
> > Ecole Polytechnique de Louvain (EPL) - Louvain School of Engineering
> > Institute of Mechanics, Materials and Civil Engineering (iMMC)
> > Center for Systems Engineering and Applied Mechanics (CESAME)
> > Tel : +32-10-472352 -- Mobile : +32-473-909930 
> > 
> >  
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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
> 
> 
> 

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