On 02 Sep 2013, at 19:38, Martin Genet <[email protected]> 
wrote:

> On 08/31/2013 01:19 AM, Christophe Geuzaine wrote:
>> On 29 Aug 2013, at 20:44, Martin Genet <[email protected]> 
>> wrote:
>>> Sorry to insist, but I'm really stuck here. Hopefully someone can help me 
>>> understand what's going on.
>>> 
>>> I made a minimal example (minimal.geo), to illustrate my problem. I first 
>>> merge the a couple STL files (STL.tar.gz), then create a couple Compound 
>>> Lines, and then eventually a Line Loop. However, the order of Compound 
>>> Lines seems to depend on whether or not I create the Line Loop (see 
>>> lines-WithoutLineLoop & lines-WithLineLoop). Is that the expected behavior? 
>>> Is there a logic behind this?
>> Hi Martin - It's a limitation of the current implementation of 
>> "CreateTopology". In this routine (which reconstructs all the connectivity 
>> data that is missing in the STL), some operations depend on sets of entities 
>> (vertices, elements), which are sorted by their memory address (pointer). 
>> The order in which features (curves) are created depends on this ordering, 
>> which itself changes from run to run.
>> 
>> We should definitely change this, as it leads to numbering are change from 
>> run to run. It's in the TODO list...
>> 
>> Christophe
> Thanks Christophe. Is it something a non-GMSH expert could work out?
> I'll give it a try. Do you have any instructions? That would help a lot…

The code is quite ugly, but might still be readable :-) It's in 
gmsh/Geo/GModel.cpp. The routine to look at is 
GModel::createTopologyFromMesh(), as well as all the subroutines called from 
there. 



> Thanks!
> 
> Martin
> 
>>> One more thing I don't quite understand, is that even Points and Surfaces 
>>> are names "ll" (see visibility.png). Is that related to the previous issue?
>>> 
>>> Thanks in advance for your help!
>>> 
>>> Martin
>>> 
>>> On 08/22/2013 03:14 PM, Martin Genet wrote:
>>>> Dear GMSH people:
>>>> 
>>>> I'm merging a bunch of stl files, and then work with lines & surfaces that 
>>>> I get using
>>>> 
>>>>> ll[] = Line "*";
>>>>> ss[] = Surface "*";
>>>> However, I can't seem to figure out the ordering of the lines & surfaces, 
>>>> especially since it seems to change from one run to another, depending on 
>>>> what I do with them. Any help with that? Thanks!
>>>> 
>>>> Martin
>>>> 
>>>> 
>>>> _______________________________________________
>>>> gmsh mailing list
>>>> [email protected]
>>>> http://www.geuz.org/mailman/listinfo/gmsh
>>> <minimal.geo><STL.tar.gz><lines-WithLineLoop.pdf><lines-WithoutLineLoop.pdf><visibility.png>_______________________________________________
>>> gmsh mailing list
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>>> http://www.geuz.org/mailman/listinfo/gmsh
> 
> 

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




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