yade-users team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

Janek Kozicki   said :

> > > Another way could be to compute the forces inside the DeusEx Engine 
> > > itself, by retrieving all sphere-box interactions and summing the 
> > > corresponding forces. In that case, is there a way to get a list of all 
> > > interactions on a box (more generally, considering a Body b0, is there a 
> > > quick way to get all interactions which have b0 as body?) ? or does it 
> > > need to go through all interactions and see which belong to the box ?
>  

> there is an InteractionContainer MetaBody::volatileInteractions, and all
> interactions used by ElasticContactLaw are there. And currently the only
> way to see which belong to the wall, is to iterate all of them and
> compare id1 and id2 with wall's id. I have some idea how to make it
> simpler and faster, so I'll improve it at some point in the future.

> But since you already have your total force - you don't need to scan all
> interactions  :) 

Oh! I forgot to mention one thing : Each wall (ok, I will use 6 walls rather than one box...) must know the total stiffness K, where K is the sum of stiffnesses over all interactions of type wall-something. Based on K, I can assign the wall a displacement such that the force on it reaches the presribed value in only one time-step (I hope this explanation is clear...).

So : I will have to iterate over all interactions in the engines (6 walls => 6 iterations over all interactions!) or modify something somewhere to increment K. From your previous answer, I realized that ElasticContactLaw is not the best place for this since it does not check the type of bodies. However, highest level functions (functions that know if one body is a wall) are not supposed to know the stiffness of elastic contacts... are they?


Few questions on SVN :

Recently, I tried to run Yade compiled from the repository sources, and for the first time, I had problems with permissions of opengl files :
"Error: Could not open /dev/nvidiactl because the permissions
are too resticitive.  Please see the FREQUENTLY ASKED QUESTIONS
section of /usr/share/doc/NVIDIA_GLX-1.0/README for steps
to correct.
Segmentation fault"

I know how to solve it temporarily (chmod on OGL files each time I start a KDE session). 
Do you have an idea if this may be due to Yade?!

More generally, do you recommend installing Yade after a complete checkout; or is it better to install it from the "official" (but very old ;)) version of Yade-all and update specific parts one by one? Is the trunk version stable currently? 

Bruno

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Chareyre Bruno
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     Institut National Polytechnique de Grenoble
     Tél : 04.56.52.86.21
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