Hi Ronald, On 8/6/07, ronaldss <[EMAIL PROTECTED]> wrote: > I need to up to date the scene of graph through several threads, therefore he > would like to know if the OSG implements some type of synchronization of > threads. > Where I can find examples?
The OSG is designed to support single threaded update, and multi-threaded rendering. It does not support multi-threaded update. Supporting general multi-threaded update would requires mutexing of most operations on the scene graph, this would utterly destroy performance. It'd also make it a really awkward to write, extended and use. All in all it would be a pretty crappy scene graph, all for a type of usage that is very specialized. So.. where does leave you... we'll not totally high and dry, one can implement high level control over access to the scene graph, this is non longer a scene graph control though, rather an application centric control. What you'll need to do is have a single mutex that each thread acquires before it can do any read/write ops on the scene graph. The main frame loop will have to use this mutex too, so that when it runs the frame() it aquires the lock so that no one else can modifiy it which its doing its update and rendering traversals. Now if you write you code carefully, acquire the lock before writing, and release it, then you should be able to get multi-thread update working safely. Performance won't be ideal, but it at least should work. Another way to tackle it is rather than using a mutex and let each thread acquire it and the modify the scene graph itself, is to do all the operations via an subclassing from osg::Operation, then placing these operations into a osg::OperationQueue that gets flushed on each new frame. The osg::OperationQueue itself can be read/written to multi-threaded so can happily handle the usage model you are looking for. The upside is that performance will be good, no long waits to acquire mutexes, the downside is that the operations are no longer synchronous w.r.t calling threads. Robert. _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
