[Gmsh] tensor file

[Laurent Stainier]

Le mardi, 13 mai 2003, à 18:05 Europe/Brussels, Christophe Geuzaine a  
écrit :

> Nicolas Moes wrote:
>> Here is a file to test tensors for gmsh 1.44.
>> On gmsh 1.39 I could see the tensors
>>
>> with 1.44, I get the message
>>
>> Loaded
>> '/scratch/moes/develop/Xfem/Merlin/Merlin/test/mechanics2d/results/ 
>> STRESS.pos'
>> Error : Tensor field visualization is not implemented
>> Error : We *need* some ideas on how to implement this!
>> Error : Send your ideas to <gmsh at geuz.org>!
>>
>
> Hmm, I don't get this message. Do you have "View.TensorType=0"?

I don't get it either.

>
> In any case, the computation of the range for tensors is wrong, since
> it's not computed in the same way as the actual field we plot... (see
> Common/View.cpp, line 205). So you probably have to select "Custom
> range" in the view options and set the min/max values by hand.
>
> Laurent: How should we fix the min/max issue? If we transform the data
> before displaying it (as is the case with the DRAW_POST_VONMISES  
> stuff),
> we have to recompute the range... Shouldn't we just write a "Von Mises"
> plugin instead, and transform the tensor data into the scalar view we
> actually want to display?

I could easily fix the min/max issue, by applying the same formula in  
Common/View.cpp as in Graphics/PostElement.cpp. Since, for now, there  
is only one way to display tensors, it would be enough. From a more  
general point of view, I recently discussed the matter with JF, and we  
agreed that the best solution would indeed be to allow the user to  
manipulate the tensor components directly, i.e. let him decide which  
scalar (vectorial??) combination of the components to display. I am not  
familiar enough with plugins to decide if they are the best way to  
implement this idea... We can keep the "Von Mises" display as a default  
(together with a plugin), since I don't see any other smart(er)  
equivalent. But if anybody has a better idea...

Laurent
--
Dr. Laurent STAINIER
Chercheur qualifié FNRS (Research associate)
LTAS-MCT, 1 chemin des chevreuils, B-4000 Liège
Tel: +32-(0)4-366-9152  -  Fax: +32-(0)4-366-9141
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