From: John Stone (
Date: Tue Jun 26 2007 - 18:06:07 CDT

  Just to chime in, I think Jana's second idea, running 16 independent
copies of VMD and sending them control messages to stay in sync is pretty
straightforward to implement, and you can base your code off of one of
these existing scripts, both of which implement sockets-based remote
control of a VMD session:

You could take one of those scripts, and essentially have your 16 independent
VMD sessions load their own trajectories, and then send them update commands
to force them to switch to a new timestep (e.g. animate goto) and update
the display etc. I won't have time to help with this as I'm going to be
out of town for the next two weeks, but you can use the scripts above
as a reference for writing your own. The Tcl home page has many other
Tcl-based networking examples.

  John Stone

On Tue, Jun 26, 2007 at 05:24:22PM -0400, Axel Kohlmeyer wrote:
> On Tue, 26 Jun 2007, Jana Black wrote:
> JB> Axel - thanks for the reply. We have a 16-screen video wall driven by 16
> JB> dual processor nodes and I would like to display 16 different
> JB> simulations simultaneously using VMD (I'm also looking at using VisIt)
> JB> but maintaining the simulations consistent in time (i.e., each display
> JB> shows the configurations at the same time). There are several ways I
> ok. so what you want to do is some sort of 'inverse IMD', i.e.
> you want to remote control multiple VMD sessions (i don't see,
> how this could be done with a single session).
> as far as i can tell, this has not been done before, but you
> have some sort of remote control of VMD sessions in the biocore
> plugins. perhaps one can utilize this and hack it to load multiple
> different visualizations instead of the same into the various
> individual VMD sessions and then use some custom frontend (Tk) GUI
> to control/synchronize all sessions.
> i could also imagine writing some sort of script that would
> load all molecules on top of each other on a (frontend) machine
> and then loop over all molecules write the visualization to
> disk and have an an external renderer pick up the file and
> render and display it on the corresponding screen. that would
> be rather slow, though, if you want that to be interactively,
> if you just want to show a given movie, you could of course
> just render individual (mpeg) movies and then play them in parallel,
> but from the elaborate setup i'd expect that you prefer interactive
> output.
> in short, i'm certain that something can be done, but i'm not
> aware of any pre-existing package (who has that kind of facility
> available anyways?), so it'll take some scripting effort to
> make it work.
> hope that helps,
> axel.
> p.s.: i'm cc'ing vmd-l in case other people there have some more
> experience (i'm very old fashioned and have not yet been fully
> convinced that these special display facilities have significant
> value besides being impressive ;-) ).
> JB> thought this could be done. One would be, if there was a parallel VMD
> JB> that visualized using distributed rendering, I could make a file in
> JB> which at each time step I had all sixteen configurations displaced from
> JB> each other in the one data file and have VMD do parallel rendering. It
> JB> would then push each frame onto the 16 screens, but by judicious choice
> JB> I would end up with one simulation in each screen. It looks as though
> JB> someone may have done this at the recent Apple WWDC displaying the
> JB> result of a simulation of a large protein. The other solution (simpler)
> JB> would be to run 16 copies of VMD, one on each processor with each copy
> JB> having the data file for its simulation, and then I just need to be able
> JB> to trigger the VMDs so as to keep them in step. I don't know if anyone
> JB> has done this in the past.
> JB>
> JB> Thanks for any help you can offer.
> JB>
> JB> -Jana
> JB> >
> JB> > JB>
> JB> > JB> Thanks!
> JB> > JB> Jana
> JB> > JB>
> JB> >
> JB> >
> JB>
> --
> =======================================================================
> Axel Kohlmeyer
> Center for Molecular Modeling -- University of Pennsylvania
> Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
> tel: 1-215-898-1582, fax: 1-215-573-6233, office-tel: 1-215-898-5425
> =======================================================================
> If you make something idiot-proof, the universe creates a better idiot.

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