Added computation of the occluders volume, scale it to a ratio of the frustum.
Added computation of the occluders volume, scale it to a ratio of the
frustum.


ntoand/osg,ghub/osg,XiaoCC/osg,stmh/osg,XiaoCC/osg,omega-hub/osg,koshman86/osg,stmh/osg,artoolkit/osg,omega-hub/osg,ghub/osg,stmh/osg,koshman86/osg,artoolkit/osg,stmh/osg,artoolkit/osg,koshman86/osg,ntoand/osg,omega-hub/osg,ntoand/osg,XiaoCC/osg,omega-hub/osg,ghub/osg,ghub/osg,ntoand/osg,XiaoCC/osg,XiaoCC/osg,stmh/osg,koshman86/osg,artoolkit/osg