Hi Lucas,

With the built-in kernel we automatically reorder the edges to form a loop, 
while the current OpenCASCADE implementation does not. Currently you thus need 
to sort the edges in the list (we'll implement this for OpenCASCADE - I have 
added it in our TODO list).

The bad news is that after fixing your file I tried to define a "Surface" on 
your loop, which uses the N-side surface filling algorithm from OpenCASCADE to 
automatically compute a BSpline surface from the boundary... and it's 
atrociously slow. You'll probably need to split the surface in smaller pieces 
for now - or look at the OpenCASCADE BRepOffsetAPI_MakeFilling class to see if 
changing some parameters could help.

Christophe


> On 19 Jun 2018, at 14:03, Lucas Blattner Martinho 
> <[email protected]> wrote:
> 
> Dear all,
> 
> I am having trouble creating line loops while using the OpenCASCADE geometry 
> kernel. A line loop that seems to be well defined for  Gmsh's native kernel 
> is regarded as an open loop by OpenCASCADE...
> 
> A more detailed description of the problem is provided below and the .geo 
> files required to repeat the issue are available attached to this message.
> 
> Does anybody understand why Gmsh exhibits sjuch a behavior ? Could anybody 
> provide some help ? 
> 
> 
> Best regards,
> 
> Lucas Blattner
> G2Elab - Laboratoire de Génie Électrique de Grenoble
> 
> 
> 
> Problem description :
>  
> 
> I am working on the geometry of a complex coil in the shape of a horse saddle 
> (see .geo files attached to this message).
> 
> File '"Lower.geo" contain the points and lines of the geometry. These were 
> generated with the help of a computer program and are loaded  by the main 
> file "Saddle.geo" with an "Include" command.
> 
> I am trying to make line loops using the lines contained  in the 
> aforementioned file to proceed creating surfaces and volumes. The lines ids 
> are stored in vectors such as Lower_Line2[], Lower_InputLine[] and so on, all 
> of which are defined in "Lower.geo".
> 
> I am particularly interested in generating a thin volume with the aid of the 
> "ThruSections"  function provided by OpenCASCADE. The first step is the 
> creation of the line loops required by this function..
> 
> That  said, I created a line loop  in the main file "Saddle.geo". The loop 
> seem to be OK, that is, it  is  closed and is  created without console errors 
> or warnings. This can be verified by taking a look at the physical regions 
> "myLoop", which correspond to the same list of lines composing the loop.
> 
> However, loading "Saddle.geo" after uncommenting the first line of the code 
> (to enable the OpenCASCADE functions) results in the following error :
> 
> Error   : Line Loop is not closed
> Error   : 'C:\xxxxxx\saddle.geo', line 6 : Could not add line loop
> 
> This error makes it impossible to continue using ThruSections. Since the line 
> loop seems to be correctly defined, I believe that it could be caused by a 
> bug....
> 
> 
> 
> <Lower.geo><Saddle.geo>_______________________________________________
> gmsh mailing list
> [email protected]
> http://onelab.info/mailman/listinfo/gmsh

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

Free software: http://gmsh.info | http://getdp.info | http://onelab.info

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