[Gmsh] normals (again)
Christophe Geuzaine
cgeuzaine at ulg.ac.be
Fri Feb 15 20:11:27 CET 2008
John Borchardt wrote:
> Hi, please see attached screenshot. The geometry normal is in red and
> the mesh normals are in green -- and they are pointing in opposite
> directions as far as I can tell.
>
> The .geo file that produced this is:
>
> Point(1) = {0,0,0,0.1};
> Point(2) = {1,0,0,0.1};
> Point(3) = {0,1,0,0.1};
> Line(1) = {1,2};
> Line(2) = {2,3};
> Line(3) = {3,1};
> Line Loop(4) = {1,2,3};
> Plane Surface(5) = {4};
>
> The console output is:
>
> Info : -------------------------------------------------------
> Info : Gmsh version : 2.0.8
> Info : Build OS : Linux
> Info : Build options : GSL NETGEN JPEG PNG ZLIB MATHEVAL ANN
> Info : Build date : Sat Aug 11 17:09:17 GMT 2007
> Info : Build host : yellow
> Info : Packager : buildd
> Info : Home directory : /home/john/
> Info : Launch date : Fri Feb 15 11:54:09 2008
> Info : Command line : gmsh plate.geo
> Info : -------------------------------------------------------
> Info : Reading 'plate.geo'
> Info : Read 'plate.geo'
> Info : Meshing 1D...
> Info : Meshing curve 1
> Info : Meshing curve 2
> Info : Meshing curve 3
> Info : Mesh 1D complete (0 s)
> Info : Mesh
> Info : Meshing 2D...
> Info : Meshing surface 5 (Plane, MeshAdapt+Delaunay)
> Info : Mesh 2D complete (0.004 s)
> Info : Mesh
> Info : 21 vertices 40 elements
> Info : Meshing 3D...
> Info : Mesh 3D complete (0 s)
> Info : Mesh
> Info : 21 vertices 40 elements
> Info : Reading 'plate.geo'
> Info : Read 'plate.geo'
> Info : Meshing 1D...
> Info : Meshing curve 1
> Info : Meshing curve 2
> Info : Meshing curve 3
> Info : Mesh 1D complete (0.004001 s)
> Info : Mesh
> Info : Meshing 2D...
> Info : Meshing surface 5 (Plane, MeshAdapt+Delaunay)
> Info : Mesh 2D complete (0 s)
> Info : Mesh
> Info : 22 vertices 42 elements
>
>
> Any ideas what's going wrong? I am using Ubuntu 7.10 x86-64 and I
You wouldn't have the "Reverse all normals" option checked in
Tools->Options->Mesh->Light, by any chance?
> installed via apt-get I believe. Thanks!
>
>
> --John
>
>
>
>
>
>
> On Fri, Feb 15, 2008 at 11:32 AM, Christophe Geuzaine
> <cgeuzaine at ulg.ac.be> wrote:
>> John Borchardt wrote:
>> > Sorry I am looking in the manual and list archives and I still don't
>> > understand...
>> >
>> > Can you tell me if the default behaviour of gmsh is such that mesh
>> > element normals are opposite of the surface normals? Am using version
>> > 2.0.8.
>> >
>> > E.g., when I mesh the following .geo, the element normals are opposite
>> > of the surface normal...
>>
>>
>> I cannot reproduce this on my machine...
>>
>>
>>
>> >
>> >
>> > Point(1) = {0,0,0,0.1};
>> > Point(2) = {1,0,0,0.1};
>> > Point(3) = {0,1,0,0.1};
>> > Line(1) = {1,2};
>> > Line(2) = {2,3};
>> > Line(3) = {3,1};
>> > Line Loop(4) = {1,2,3};
>> > Plane Surface(5) = {4};
>> >
>> >
>> >
>> > Thanks,
>> >
>> >
>> > --John
>> >
>> > _______________________________________________
>> > gmsh mailing list
>> > gmsh at geuz.org
>> > 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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>>
>>
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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