Drawables,StateSet, and osgDB::Registry.
Added cleanup_frame() from to osgProducer::OsgCamerGroup to help with proper
clean of OpenGL objects before exit, and modified osgviewer, osghangglider,
osgwindows examples to do the extra frame call to cleanup_frame() before exit.
much time is allocated to compiling and deleting OpenGL objects, also
added support into osgProducer::OsgSceneHandler.cpp for these new parameters.
The new cotrols are:
DatabasePager::s/getTargetFrameRate(..)
DatabasePager::s/getMinimumTimeAvailableForGLCompileAndDeletePerFrame()
DatabasePager::s/getMaximumNumOfObjectsToCompilePerFrame()
setClearColor so that it passes on its value to Camera::setClearColor(), and
changed OsgSceneHandler to use the Camera::getClearColor() on each new frame
to ensure that it reflects the settings of the camera correctly.