From: Don Burns (don_burns++at++peru.engr.sgi.com)
Date: 01/25/2000 08:51:17
On Jan 25, 3:57pm, rusguss++at++viso2.rus.uni-stuttgart.de wrote:
> Subject: RE: panoramic on Performer linux?
> Hi,
>
> I am looking for a way to distribute a performer scene graph to get something
> like a panoramic view. My idea is to have one master computer that control
the
> scene graph, the sync and so on, and several slave computers that display
their
> view of the scene graph.
> One possibility would be to store the scene graph using: pfdStoreFile to save
it to
> a file, loading the file as a binary and sending it to all the slaves (TCP or
UDP).
> That would work for the scene startup but what do I do when the scene graph
changes ?
What you describe is OK at init. Actually, a much easier solution is to just
NFS mount the directory where your scene graph is on the slave machines.
Scene graph changes can mean several things.
1) pfDCS/pfFCS updates. This is where you have a moving model, or some
animation that needs to update on a frame basis. The source of the updates can
either be just a repeating pattern, that can be loaded from file at start up
and played over repeatedly, or dynamic external data. In the latter case, you
will want to update a small amount of information which can be transmitted with
the channel eyepoint information over the ethernet.
[Note: There is an optimal packet size for UDP transmissions which is large
enough to contain both eyepoint data and several dozen moving model updates.]
2) Database Loading, Unloading, and Merging. This is costly no matter what,
and requires a bit of work to tune so as not to disturb frame rate that much.
For this I really recommend a local file system, since NFS traffic will
disturb eyepoint updates over the ethernet. Even with more than one NIC per
machine, you can cause resource contention. However, just as moving model data
can be sent with eyepoint, so can simple commands to load and unload parts of
the database, using the DBase phase.
3) Special Effects. This is kind of a combo of the past two. Effects (like
explosions) need to be triggered by something external, but can be carried out
locally on each machine.
-don
>
>
> Thanks
> Pablo Gussmann
>
>
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>-- End of excerpt from rusguss++at++viso2.rus.uni-stuttgart.de
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