[osg-users] [Any feedback welcome] possible lack of robustness of the VAO path

[Robert Osfield]

You have created a scheme where you are caching a nodes that can't be
seen directly by the viewer so it isn't able to do the normal clean up
that it does prior to cleaning up the graphics contexts.  Try doing a
releasreGLObjects() on the nodes cached on the callback prior to
removing them.  You also need to add a mutex to the callback as it's
potentially run multi-threaded.

On Sat, 19 Jan 2019 at 01:04, Julien Valentin
<julienvalentin51 at gmail.com> wrote:
>
> The following code exibits crashes with VAO path
>
> Code:
>
> #include <osgUtil/MeshOptimizers>
> #include <osgGA/TrackballManipulator>
> #include <osgGA/FirstPersonManipulator>
>
> #include <osgViewer/Viewer>
> #include <osgViewer/ViewerEventHandlers>
>
> #include <osgDB/ReadFile>
> #include <osgDB/WriteFile>
>
>
> class GeomLoaderCB : public osg::Camera::DrawCallback//  osg::NodeCallback
> {
> public:
>     int _thresremoval;int _nbaddedatatime;
>     GeomLoaderCB(int thresremoval=1,int nbaddedatatime=1):_nbaddedatatime(nbaddedatatime),_thresremoval(thresremoval) {}
>     mutable std::list<osg::ref_ptr<osg::Geometry> > _geoms;
>     void setGeometryList(osgUtil::GeometryCollector::GeometryList c) {
>         for(auto f : c)
>             _geoms.push_back(f);
>     }
>     virtual void operator () (const osg::Camera&  camera ) const {
>         osg::Node * node=const_cast<osg::Camera*>(&camera)->getChild(0);
>
>         if(_geoms.empty())return;
>         osg::ref_ptr<osg::Group>  gr = node->asGroup();
>
>         if(gr->getNumChildren()>_thresremoval)
>         {
>             OSG_WARN<<"removing "<<  gr->getChild(0)<<std::endl;
>             gr->removeChildren(0,1);
>             return;
>         }
>
>         std::list<osg::ref_ptr<osg::Geometry> > ::iterator it= _geoms.begin();
>         int cpt=0;
>         while(it!=_geoms.end()&&cpt++<_nbaddedatatime ) {
>             gr->addChild((osg::Drawable*) (*it)->clone(osg::CopyOp::DEEP_COPY_ALL));
>             OSG_WARN<<"add "<<  (*it ) ->getVertexArray()->getNumElements()<<std::endl;
>             it=_geoms.erase(it);
>         }
>         return;
>     }
>
> };
>
>
> /// This demo reproduce a bug with OSG_VERTEX_BUFFER_HINT=VAO
> /// it collecte drawables given in arg then add and remove them at runtime
> int main(int argc, char **argv)
> {
>     osg::ArgumentParser args(&argc,argv);
>     unsigned int  geomcountaddedatatime=1,geomcountabovewichweremove=1;
>     while(args.read("--add",geomcountaddedatatime) ) { }
>     while(args.read("--remove",geomcountabovewichweremove) ) { }
>     osgUtil::GeometryCollector geomcollector(0,osgUtil::Optimizer::ALL_OPTIMIZATIONS);
>
>     args.getApplicationUsage()->setApplicationName(args.getApplicationName());
>
>     osg::ref_ptr<osg::Node > loaded=osgDB::readNodeFiles(args);
>     if(loaded.valid())
>     {
>         loaded->accept(geomcollector);
>
>         osg::Group * root=new osg::Group;
>         //osg::Camera * root=new osg::Camera;
>         GeomLoaderCB * loader=new GeomLoaderCB(geomcountabovewichweremove,geomcountaddedatatime);
>         loader->setGeometryList(   geomcollector.getGeometryList() );
>
>         osgViewer::Viewer viewer;
>         viewer.addEventHandler(new osgViewer::StatsHandler);
>         viewer.addEventHandler(new osgViewer::WindowSizeHandler);
>         viewer.addEventHandler(new osgViewer::ThreadingHandler);
>
>         viewer.realize();
>         viewer.setSceneData( root);
>
>         viewer.getCamera()->setFinalDrawCallback(loader);
>         loaded=0;
>
>         viewer.run();
>     }
> }
>
>
>
>
> if you want my test sample:
> https://drive.google.com/file/d/0BxIH-jcsgYDdTG5ha21HZE1jX1E/view?usp=sharing
> for ex It fails  with args :
> BIGCITY.ive --remove 150 --add 100
>
> I believe there's a bug....so I'd be glad if someone validate it...
> note: toggling statshandler prevent crash
>
> Thanks in advance
> Cheers
>
>
>
>
> mp3butcher wrote:
> > Hi all,
> > I wrote a sample code exibiting crash with my scene
> > https://github.com/openscenegraph/OpenSceneGraph/issues/692
> >
> > If you'd have 5 min to waste, i would be glad you confirm with your own scene...
> >
> > Thank you!
> >
> > Cheers,
> > Julien
>
>
> ------------------------
> Twirling twirling twirling toward freedom
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=75508#75508
>
>
>
>
>
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