Hi Paul, On 7/3/07, Paul Martz <[EMAIL PROTECTED]> wrote:
Okay, but because computeBounds() is const, I have to cast away const in order to perform operations on the scene graph within this function.
Casting away const'ness is should be see as "advanced" usage, some that most usage models won't require, but if you know what your are doing and that it won't break any threading then you'll be OK to just go ahead and cast away constness.
Furthermore, when I do this, I see crashes in multidisplay environments, probably due to a thread collision caused by modifying the scene graph in one thread while another accesses the same part of the scene graph.
Well you'll need to write the code so its thread safe... one way around this is to stick a viewer->getSceneData()->getBound() before the call to renderingTraversals(); Crude way of forcing a single threading computeBound() but effective.
Taking a look at CullVisitor, it's not clear to me how you ensure that computeBounds() is only called once per frame in multidisplay environments (where multiple cull traversals would be running concurrently). Can you explain how this is handled?
The computeBounds() themselves just compute a bounding volume they don't actually modify anything. The getBound itself does the modification of the cached bounding volume, and can do so virtual of the _boundingBox/_boundingSphere being mutable. The getBound does try to make the serialize the access to the bounding volume variable, rather it lets multiple threads go and do the compute and lets them all apply their values - they will all compute the same values anyway so there isn't any danger in this. Robert. _______________________________________________ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
