From: Dipesh Bhattarai (
Date: Fri Feb 12 2010 - 09:24:58 CST

Thanks for your reply. The problem was with transformation of the tracker
position with transformation_matrix in the display device. It is solved now.

As for the subclassing VMD tracker class, I let VR Juggler handle all the
detail about accessing and updating the tracker status. I use the
information received from VR Juggler and pass that to VMD. So far, selection
works fine. But adding programmability to the selection is creating problem.
That is more to do with lack of GUI in the multiprojector environment than
anything other. I still don't know how to proceed with that. Buttons in the
wand are all used up for one functionality or the other.



On Fri, Feb 12, 2010 at 12:26 AM, John Stone <> wrote:

> Hi,
> Have you implemented VMD tracker subclass(es) for your 3-D tracker?
> I would begin by doing that, otherwise you may be way off in
> your coordinate system. If you have a tracker subclass implemented,
> then you should be able to use the various "tool" modes in the
> VMD tool menu to see the position of your tracker on the screen,
> and to interact with button events etc. Once you have that sorted
> out, you could implement other interactions beyond what's already there.
> Without seeing the entirety of the code you've written, it is difficult
> to judge what you're having trouble with. Unless VMD is actually drawing
> the pointer for you via the normal class hierarchy, I cannot say
> whether what you're seeing on the screen with your pointer
> is even relevant as far as the pick calls go. If you can provide me
> with the code you're working with, I can try and give you suggestions
> for solving your problem as time allows.
> Cheers,
> John Stone
> On Mon, Feb 08, 2010 at 10:57:03AM -0600, Dipesh Bhattarai wrote:
> > Hello all,
> >
> > I am trying to select subset of the molecule using a 3D pointing
> device.
> > The device is tracked by Intersense IS-900 tracking system and is
> accessed
> > through VRPN. I am using VR Juggler to tie the VMD with the
> multiprojector
> > display and the device. I call app->pickList->pick_check() method to
> see
> > if there are any atoms near the current position of the 3D pointing
> > device. Even though the location of the cursor looks to be
> overlapping,
> > the method does not actually return anything. Sometime it seems to
> select
> > something, but the picked items does not actually correspond to the
> item
> > near the cursor position. I believe it is because the tracker position
> and
> > VMD use different coordinate systems.
> >
> > How do I transform the 3D cursor position so that it correspond to the
> > coordinate system VMD use? I would appreciate any pointer to the
> solution.
> >
> > Thanks,
> > Dipesh
> >
> > --
> > Dipesh Bhattarai, PhD
> --
> NIH Resource for Macromolecular Modeling and Bioinformatics
> Beckman Institute for Advanced Science and Technology
> University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
> Email: Phone: 217-244-3349
> WWW: <>
> Fax: 217-244-6078

Dipesh Bhattarai, PhD