Hi Andrew, You could use Drawable::DrawCallback and override the rendering of your mesh and implement your own code for hiding/displaying different sets of primitives. However, as you mention, osg::Geometry::drawImplementation() is actually pretty complicated so reproducing this then making it even more complicated with the optional primitive set rendering would be be rather daunting.
In the svn/trunk version of osg::Geomtry::drawImplemtation() the code has been rewritten completely and is actually far more straight forward and readable - all achieved by using a couple of helper classes. This would certainly be the easier base to use, with the helper classes being reusable directly. The other approach would be just manage the osg::Goede + osg::Geometry so that the different sets of primitives can be turned on/off via NodeMasks combinations. To help simplify management you could write a custom osg::Node/osg::Group that automatically manages an internal scene graph that hides the complexity of all the separate osg::Geometry. Robert. On Mon, Dec 7, 2009 at 2:56 AM, Andrew Cunningham <o...@a-cunningham.com> wrote: > I want to do something a little 'odd' and am not sure of the best way to do > this. > - assuming a 'large' number of (tri or quad) primitives in a primitiveset > (say 100K-500K+) I want to hide ( not draw) a user-defined subset of those > primitives. > > - the user scenario is that the user selects a subset of primitives from the > full geometry then "hides" them. The user can also "Un-hide" any hidden > primitives at any time. > > - I could laboriously keep multiple geometries but was wondering if it is > possible to override one of the drawing functions to "test" for membership in > a hidden set for each primitive. Obviously this would follow the slow path, > Or ???. I have looked at the primitiveset drawing code but got lost in the > complexity of VBO vs displaylist vs slow path etc. > > > Thanks > Andrew > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=20989#20989 > > > > > > _______________________________________________ > 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
