[Gmsh] importing/merging geometries

[Christophe Geuzaine]

On 11/05/11 03:33, Mikhail Artemiev wrote:
> I had not only this problem when I exported geometry from Salome in step
> file and tried to open it in Gmsh.
> For example, if I defined an ellipsoid (see script below) and then
> opened it in Gmsh (or FreeCAD) I got nothing.
>
> import geompy
> Sphere = geompy.MakeSphere(-100, -100, -100, 100)
> Scale = geompy.MakeScaleAlongAxes(Sphere, None, 1, 3.5, 0.5)
> geompy.Export(Scale, "D:/scale.step", "STEP")
>
> I asked about this strange behavior in Salome forum.
> One said me:
>
> Indeed, it is a bug (or a limitation, I don't know) ... We will analyze
> that.
> For the moment, you should export as brep (this one works and should be
> readable by FreeCAD ans Gmsh)
> geompy.Export(Scale, "D:/scale.brep", "BREP")
>
> I exported single sphere, ellipsoid, sphere intersecting cube, in brep
> format - all works fine.
> Hope this helps.
>
> But I worry about the difference between step and brep formats for
> building meshes in Gmsh.
> Do these formats have the same information about geometry? Or one of
> these is better than other?
> Can anybody tell me?
>

Brep is the native OpenCASCADE format and Gmsh uses OpenCASCADE to read 
the brep files, so using brep is a good idea: there is no translation 
involved.

> Mikhail Artemiev
>
> ----- Original Message ----- From: "Bart Vandewoestyne"
> <Bart.Vandewoestyne at telenet.be>
> To: "Mikhail Artemiev" <artemiev.mikhail at ngs.ru>
> Sent: Tuesday, May 10, 2011 4:31 PM
> Subject: Re: importing/merging geometries
>
>
>> On Tue, May 10, 2011 at 11:45:24AM +0700, Mikhail Artemiev wrote:
>>> Hi, Bart!
>>>
>>> On 23 March 2011 you wrote:
>>>
>>> ----------
>>>
>>> Thanks for pointing me to Salome. I've played a bit around with
>>> it and created a simple 3D geometry consisting of the union of a
>>> cube and a sphere:
>>>
>>> http://www.kuleuven-kortrijk.be/~bartv/cube_and_sphere.hdf
>>>
>>> I exported this to a STEP file:
>>>
>>> http://www.kuleuven-kortrijk.be/~bartv/cube_and_sphere.step
>>>
>>> but when I try to open this STEP file in gmsh with
>>>
>>> $ gmsh cube_and_sphere.step
>>>
>>> i get errors:
>>>
>>> Error : Something wrong in edge loop
>>> Warning : OCC STL triangulation failed
>>>
>>> ------------
>>>
>>> I encountered with the same problem using FreeCAD and Salome.
>>> Did you solve this problem?
>>
>> Nope. Haven't received a solution and haven't looked at it
>> anymore... it's not so urgent for me. If you have solutions,
>> please share!
>>
>> Regards,
>> Bart
>>
>> --
>> "Share what you know. Learn what you don't."
>
>
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>


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