Hi Cully,
It seems like the problem that split window or frame buffer to different
part.
There are two way to do this in osg.
1.add slave camera to osgViewer::view,each camera has different
graphiccontext.
2.add osgViewer::view to osgViewer::compositeViewer,and one osgViewer::view
correspond one camera,and has the same graphiccontext.
method 1 prefer the situation that each camera has different view or proj
matrix but has same node tree.like Virtual Reality rendering,or cad design.
method 2 prefer each view(camera) has independent node tree.Like multi-doc edit
in Word.
And the thread problem,I think you'd better do update in osg update thread,like
add updateCallback to node.By this way,your thread will not have sync problem
with osg render thread.
To be honest,I don't pretty understand your problem.
you'd better simplify your code to a problem example.
Qi Yu.
------------------ Original ------------------
From: "Antoine Cully"<antoinecu...@hotmail.com>;
Date: Thu, May 23, 2019 00:49 AM
To: "osg-users"<osg-users@lists.openscenegraph.org>;
Subject: [osg-users] Running multiple (independent) viewers in differentthreads
Dear OSG Community,
I searched quite a lot through the source code and the beginner guide, but I
was unable to find a way to make this work, so I am posting here hoping that
you could help me.
I am developing a tool to run physical simulations (of robots) in parallel.
This tool is used to run stochastic optimisation (like deep reinforcement
learning) algorithms, and for this I need to be able to run several, but fully
independent, simulations in parallel thanks to multithreading. This enables to
collect data faster and for instance with a 32-core multithreaded CPU the
speed-up factor is quite significant.
In each simulation, I have one camera that observes the environment, and which
can be used to change the behaviour of the robot running in this simulation.
The camera is currently implemented as a pbuffer following closely the
osgscreencapture example. The actual code of the camera can be found on github,
but apprently I am not allowed to post URLs at the moment.
The multithreading is managed by TBB (an Intel library that I have been using
for 6 years now).
If I run my code in a "sequential mode", i.e., all the simulations running one
after the other, everything is going well. However, if I run it in parallel,
then I have some unstable behaviours. For instance, I can have a segmentation
fault happening after a random number of simulations or suddenly after again a
random number of simulations, the pbuffer cannot be created anymore (OSG
displays "Error: Unable to create pbuffer."). It seems to me that
"::osg::ref_ptr<::osg::GraphicsContext> pbuffer =
::osg::GraphicsContext::createGraphicsContext(traits.get()); "
does not work in this setup.
If I remove the cameras (and all OSG components) from my code, it is working
well in parallel, but of course I would like to have cameras in my simulations.
Ideally, I would like to run OSG in a single-thread mode and let TBB distribute
the different instances of the simulator and OSG in different threads, but even
with
"setThreadingModel(osgViewer::ViewerBase::ThreadingModel::SingleThreaded);" it
does not work.
I tried different threading modes, with the same result.
So here is my question:
What would be the most appropriate way to run several independent viewers and
pbuffers, each in a different thread?
The rendered scenes are really simple (no texture, just several primitive
shapes) and I am only rendering a couple of frames in each simulation, so I
don't need a complex threading model for OSG.
Some information about my system:
- Ubuntu 18.04
- OSG 3.6.4
Thank you in advance for your help.
Best regards,
Antoine
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=76134#76134
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