Re: [vrjuggler-info] Cluster Configuration timing

[Aron B. <ar...@vr...>]

Terry Jordan wrote:

> I have a setup for passive stereo where there are 2 machines running 
> Surface viewports each of them having the same corners and a 
> controller pc to accept keyboard input.  The problem I am having is 
> that the data being visualized needs to be synchronized (they have to 
> on the same frame) between the 2 machines otherwise the setup doesnt 
> work.  These cards dont have hardware frame locking.  Is there someway 
> to accomplish this?  I am using all three cluster plugins.
>
> When I run the one wih the controller pc first it will stop the first 
> data visualizer but only after a few frames have passed, which puts 
> the 2 visualizer out of sync.
>
> OS:  RedHat8.0
> VRJ:  2.0 Alpha
> Graphics:  GeForce4 4600
>
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Starting all cluster machines at the same time has been a problem in the 
past. A few changes that have been made in the CVS source tree over the 
past week have strengthed the barrier while waiting for all machines to 
start. While using Alpha1 you can use UserData to share the state of 
your data. If you share the state of this data over the cluster you can 
add machines at anytime and maintain syncronization. For example if we 
needed to share a navigation matrix and the machines start at the same 
time you could have your navigation matrix on each machine being updated 
using input from a keyboard. The problem of course occurs when one 
machine starts earlier than the others and gets input before the others. 
This problem can be overcome by sharing the navigation matrix using 
UserData and assigning one machine to be responsible for updating this 
matrix. If you have any questions about using UserData you can refer to 
the sample application in 
$VJ_BASE_DIR/share/vrjuggler/test/cluster/applicationData or feel free 
to e-mail questions to the mailing list.

-Aron