[GiDlist] Swapping normals and the effect on conditions

[Kendon, Tim]

Dear Gidlist

I have meshed a 2D geometry (part structured), which required me to both
swap the normals to the same sense and then swap them all to point in the
opposite direction.

In the process of swapping the normals to the opposite direction, I
outputted two ascii *.txt files, one before the swap and one after the swap,
in order to look at my conditions and the effect of the swap. I also
outputted *.msh files at the same time. to look at the effect on th e mesh
of the swap. Whilst I noticed the *.msh file before and after had undergone
the necessary change I noticed the conditions had not. The face information
for each condition in the two *txt files was the same

Surely this can't be the case, if the mesh changes it's ordering surely the
conditions ought to point to different faces. I would appreciate any
enlightenment. Furthermore I apologise if this has already been addressed in
your list already.

Tim Kendon

[Enrique Escolano]

You swap directly the mesh or the geometry?
If you swap the mesh, it's possible that some condition over face elements
are corrupted (i must check this case in more
detail to request).

Best, you must swap the geometric entity normals (surfaces or lines), and
then regenerate the mesh. (the element's normal is the same
as the source geometric entitie's normal)

If you change directly the mesh element normals, then if you remesh this
manually work is lost, and the orientation must be set another time.

Enrique Escolano

----- Original Message -----
From: "Kendon, Tim" t.kendon at imperial.ac.uk
To: "'gidlist at gid.cimne.upc.es'" gidlist at gatxan.cimne.upc.es
Sent: Monday, August 11, 2003 1:24 PM
Subject: [GiDlist] Swapping normals and the effect on conditions


Dear Gidlist

I have meshed a 2D geometry (part structured), which required me to both
swap the normals to the same sense and then swap them all to point in the
opposite direction.

In the process of swapping the normals to the opposite direction, I
outputted two ascii *.txt files, one before the swap and one after the
swap,
in order to look at my conditions and the effect of the swap. I also
outputted *.msh files at the same time. to look at the effect on th e mesh
of the swap. Whilst I noticed the *.msh file before and after had
undergone
the necessary change I noticed the conditions had not. The face
information
for each condition in the two *txt files was the same

Surely this can't be the case, if the mesh changes it's ordering surely
the
conditions ought to point to different faces. I would appreciate any
enlightenment. Furthermore I apologise if this has already been addressed
in
your list already.

Tim Kendon

_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist