Hey Sebastian, I've been looking at this off-and-on for a while now, though I have no clean solution. From my investigation it looks like the osg::CullVisitor tweaks the _computed_znear and _computed_zfar values to their needed settings during the handlle_cull_callbacks_and_traversal() call in the apply(osg::Camera&) method. Once the traversal call is complete, the znear and zfar values are correct for all the geometry under that camera. The problem is that between that point and the code a few lines down where the z-values are reset for the next camera there is no mechanism to install a callback to retrieve the computed values.
The two solutions I was going to try were: 1) Attach a custom node to the scenegraph in a way that assures it is the last node traversed, is always visited, yet doesn't influence the scene bounds, and then cache off the znear and zfar values from the CullVisitor using a cull callback on that node (seems tricky to manage) Or: 2) Subclass the osg::CullVisitor (which we've already done anyway in our project), copy/paste the virtual apply(osg::Camera&) method body, and insert the code that I needed to cache / broadcast the z-values after the traversal. In either case the callback or broadcast mechanism could update the projections for any other cameras down the pipeline before they're hit by the CullVisitor. What I really want is the ability to give one camera references to other cameras as sort of "projection slaves" and have the osg::CullVisitor set the slave projections after the traversal. I haven't dug through the osg code enough to see if that paradigm is valid or if there's a more obvious solution I'm overlooking. Note that this is all in theory. I haven't been tasked to fix this issue yet in our code, we've just been using hard-coded fixed near/far values in the interim. - Andy ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50742#50742 _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
