Re: [osg-users] Running viewer loop and physic calculations in different threads
Cory, Paul and all, Thank you for your answers. I have finally solved it by using Intel's TBB, among which there are some functions to launch threads. Best regards, Alfonso 2009/5/22 Alfonso Callejo Goena > Hello everyone: > > I'm developing a OSG-based graphic engine for a real time mechanical > simulator. I would like that the physics and the graphic display would run > in separate threads so that they could work independently without bothering > each other. The communication between them is a kind of buffer or list to > which the physics program pushes the last calculation and the graphic > program pulls the appropriate one. > I don't know which is the best (and most simple) way of setting up and > managing the threads. Does the osgViewer class have a way of doing this? > Where can I find an example which follows this technique? > > Thank you, > Alfonso > ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Running viewer loop and physic calculations in different threads
Alfonso,
I've distilled my code down. I hope I haven't cut out too much. The
most complicated part for me was getting the halting sequence correct.
I tell the viewer to stop drawing and then have to wait until the
viewer thread is finished and notifies me that it is complete.
I have a view class that "owns" the scene graph and the display. It
looks something like:
class MyView {
private:
/// the OSG view onto the scene
osg::ref_ptr m_viewer;
/// the thread sets this to {...@code true} when the viewer thread has
stopped
bool m_viewerThreadStopped;
/// the mutex to protect access to {...@link #m_viewerThreadStopped}
boost::mutex m_viewerThreadStoppedMutex;
/// the condition variable for signalling {...@link
#m_viewerThreadStopped} has been set
boost::condition_variable m_viewerThreadStoppedCond;
public:
MyView() : m_viewerThreadStopped(false) { }
~MyView();
void initialize();
...
};
MyView::~MyView() {
if (m_viewer) {
boost::unique_lock
lock(m_viewerThreadStoppedMutex);
m_viewer->setDone(true);
// this while loop has to be here because of spurious wakes
while (!m_viewerThreadStopped) {
// unblock and wait for it to signal that it is done running
m_viewerThreadStoppedCond.wait(lock);
}
m_viewer->stopThreading();
}
}
void MyView::initialize() {
// set up the scene graph here
...
// start the thread that does the OSG rendering
boost::thread(startThread, m_viewer, &m_viewerThreadStopped,
&m_viewerThreadStoppedMutex, &m_viewerThreadStoppedCond);
}
void startThread(osg::ref_ptr pViewer,
bool* doneFlag, boost::mutex* mutex,
boost::condition_variable* cond)
{
pViewer->run();
boost::lock_guard lock(*mutex);
*doneFlag = true;
cond->notify_all();
}
Alfonso Callejo Goena wrote:
Cory Riddell writes:
Hi Alfonso,
I'm doing something similar to what you are doing. My viewer is running
in it's own thread. I have a shared object that I use to communicate
between the threads. If you are looking for sample code, I can try to
distill what I have to something relatively simple.
I'm using the boost threads library. It seems to work quite well and is
cross platform. Have you written multi-threaded apps before? Are you
familiar with mutexes (mutices?), conditions, volatile variables,
spurious wakes, etc...?
If you aren't familiar with the boost stuff, I would recommend spending
some time getting familiar with it.
Aside: if anybody can explain why spurious wakes exist, I'd love to
hear an explanation.
Cory
Hi Cory,
I would appreciate very much your sample code, because I don't have much
experience in this issue.
Did you consider using what Paul has suggested (osgDB::DatabasePager)? In my
case the physical calculations are in fact a standalone program, and it is not
just "loaded data"...
Thank you very much,
Alfonso
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Re: [osg-users] Running viewer loop and physic calculations in different threads
Cory Riddell writes: > > > Hi Alfonso, > I'm doing something similar to what you are doing. My viewer is running > in it's own thread. I have a shared object that I use to communicate > between the threads. If you are looking for sample code, I can try to > distill what I have to something relatively simple. > I'm using the boost threads library. It seems to work quite well and is > cross platform. Have you written multi-threaded apps before? Are you > familiar with mutexes (mutices?), conditions, volatile variables, > spurious wakes, etc...? > If you aren't familiar with the boost stuff, I would recommend spending > some time getting familiar with it. > Aside: if anybody can explain why spurious wakes exist, I'd love to > hear an explanation. > Cory Hi Cory, I would appreciate very much your sample code, because I don't have much experience in this issue. Did you consider using what Paul has suggested (osgDB::DatabasePager)? In my case the physical calculations are in fact a standalone program, and it is not just "loaded data"... Thank you very much, Alfonso ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Running viewer loop and physic calculations in different threads
Hi Alfonso, I'm doing something similar to what you are doing. My viewer is running in it's own thread. I have a shared object that I use to communicate between the threads. If you are looking for sample code, I can try to distill what I have to something relatively simple. I'm using the boost threads library. It seems to work quite well and is cross platform. Have you written multi-threaded apps before? Are you familiar with mutexes (mutices?), conditions, volatile variables, spurious wakes, etc...? If you aren't familiar with the boost stuff, I would recommend spending some time getting familiar with it. Aside: if anybody can explain why spurious wakes exist, I'd love to hear an explanation. Cory Alfonso Callejo Goena wrote: Hello everyone: I'm developing a OSG-based graphic engine for a real time mechanical simulator. I would like that the physics and the graphic display would run in separate threads so that they could work independently without bothering each other. The communication between them is a kind of buffer or list to which the physics program pushes the last calculation and the graphic program pulls the appropriate one. I don't know which is the best (and most simple) way of setting up and managing the threads. Does the osgViewer class have a way of doing this? Where can I find an example which follows this technique? Thank you, Alfonso ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] Running viewer loop and physic calculations in different threads
Hello everyone: I'm developing a OSG-based graphic engine for a real time mechanical simulator. I would like that the physics and the graphic display would run in separate threads so that they could work independently without bothering each other. The communication between them is a kind of buffer or list to which the physics program pushes the last calculation and the graphic program pulls the appropriate one. I don't know which is the best (and most simple) way of setting up and managing the threads. Does the osgViewer class have a way of doing this? Where can I find an example which follows this technique? Thank you, Alfonso ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
