First, let me assure you that clustering _is_ perfectly possible with OSG. I've developed several simulators that use clustering for multi-display rendering all based on OSG. That being said, there is no specific built-in support for clustering in either Producer or OSG.
We've talked about having clustering very early on and my intention is to have clustering (hosting) available in the run-time module for Producer2 (now being code named "Pishrant"). What has kept us from building this in to current versions, however, is 1) motivation and 2) architectural design decisions.
Actually 1) and 2) are related. Design for a "clustered" solution must take into account at what level you provide data coherency between networked nodes. This can range from simply providing the eyepoint to all nodes down to distributing OpenGL calls (a wireGL approach). There are obvious trade-offs having to do with data transfer sizes, latency and performance.
These trade-offs are quite application dependent. For a flight simulator, for example, the scene itself stays quite static and the data distributed is really down to a few matrices, time, frame number, and the eyepoint. Each node runs an independent viewer, but all are synchronized in "data sync". Even if a paged database is used, a copy of the pager can be run on each node. The database data can be paged from either a copy of the database on each node, the network, or a SAN.
Now, if you want to be able to write a single program and running on one node, update the scene graph dynamically from that one node and have all nodes synchronously update the scene graph, then, no, this capability is not in OSG or Producer today. I don't know the OpenSG approach for doing this although I do know that they have "cluster support". If there is any purpose to the OSG way of doing things, however, it is not to impose a particular level of data cohesion, and possibly avoid overhead where it is not needed.
So, the question needs to be asked more specifically. Rather than a general, "cluster support", what level of data cohesion is really needed in the application. It may only be a half a day of programming to make it work.
-don
On 10/9/06, Jan Ciger <[EMAIL PROTECTED]> wrote:
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Hello,
I would like to ask the resident OSG gurus about a clustering solution
for OSG. We are attempting to build a new application for VR therapy
purposes on OSG, however there is a constraint that it has to run on
three different kinds of systems - a desktop with an HMD, a large stereo
wall and a CAVE.
The group running the CAVE is using OpenSG at the moment and we would
like to get them to use OSG instead. However, OpenSG has a built-in
support for rendering on clusters of networked machines. Does somebody
know whether (and how) is it possible to achieve this with OSG? I am
speaking about clustering beyond the simple viewpoint synchronization.
OpenSG seems to have support for transparent replication and
synchronization of bits and pieces of the scenegraph across the cluster.
This is quite a big deal to get working right and I didn't see something
like this with OSG so far. Is there something similar available for OSG
already?
Thanks in advance,
Jan
- --
Jan Ciger
GPG public key: http://www.keyserver.net/
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