Hi, > Hello Simon, > > Simon Haegler wrote: >> osgHello >> >> how do the following options affect the render performance? especially the >> culling threshold is of interest, as i'm making heavy use of occlusion >> culling. >> >> _renderAction->setSortTrans(0); >> _renderAction->setZWriteTrans(0); >> _renderAction->setLocalLights(0); >> _renderAction->setCorrectTwoSidedLighting(1); >> _renderAction->setOcclusionCullingThreshold(0); // hierarchical multi frame >> >> are there any other options i should consider for the optimization of >> rendering performance? > > I can not really comment on this, maybe Andreas, who implemented the OC > support for 1, can share his experiences ?
with the culling threshold you can skip the occlusion test for small geometries the value represents the number of vertices. The hierarchical multi frame occ tries to minimize the occlusion tests. In the first frame all geometries are tested in the next frame (if possible) it tests the geometry parent nodes and so on. To get the best performance you need to create a quite deep scenegraph hierarchy. Just group rooms and buildings below a group node. So it is possible to skip a whole building or room with only one occlusion test. >> my scene (citymodel) contains about 100k nodes, 16mio (transformed) vertices >> and makes heavy use of instancing (reuse of geocores) and material groups. > > ok, that should keep the number of display lists/vbos and state changes > low, the number of nodes could be a problem though. Is there a chance > that you can collapse the scene more, without loosing too many > possibilities for occlusion or frustum culling ? > >> with the camera on eyelevel and activated hierarchical multiframe occlusion >> culling the framerate is about 24fps on a nvidia 8800 ultra. render >> resolution is 800x600. > > what happens at higher resolutions, i.e. are you reaching/at the fill > limit? > >> do you have general optimisation ideas or is this the maximal framerate i >> can >> expect? when does the use of VBOs make sense? displaylist caching? > > For a (mostly) static scene like a city and on your hardware that has > plenty of memory on the graphics card, VBOs sound like a good idea. > > Hope it helps, > Carsten > > PS: It would be great if you could give some feedback on this list, what > effect if any the optimizations you might try give you. Thanks. Using VBO's is a good idea but don't create tri strips just simple triangle lists. For optimal speed you need to cache optimize the indices (http://ati.amd.com/developer/gdc/2007/Sander-Fast_Triangle_Reordering(SIGGRAPH'07).pdf). Rendering many nodes like 100000 is quite slow try to merge as much as possible in one geometry. Andreas > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2008. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Opensg-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/opensg-users > ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Opensg-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/opensg-users
