This is a great topic and I am very interested to learn the facts about this.
In osgEarth using display lists (on my NVIDIA GTX275) yields a sizable performance boost over VBOs in many scenarios. In some of my tests I've seen a 50%+ reduction in DRAW and GPU times. But there are strange artifacts that seem to be related to the use of display lists with shaders that prevent me from making DL's the default. Driver bugs perhaps? All I can find is speculation and guessing when it comes to using shaders wtih DLs. Same goes for performance comparisons. Some swear you can always get the same or better performance using a VBO, but it's hard to track down the "best practices" for doing so. Some say NVIDIA drivers have a special code path that speeds up DL's compared to VBOs. Some say it's all about the number of size of your primitive sets. Obviously VBOs are the future since DLs are deprecated. So assembling some best practices for their application is critical! Glenn Waldron / @glennwaldron On Thu, Jan 24, 2013 at 1:57 PM, Robert Osfield <robert.osfi...@gmail.com>wrote: > Hi Terry, > > On 24 January 2013 18:21, Terry Welsh <mogu...@gmail.com> wrote: > > Mathias's point that display lists are deprecated are probably the > > best reason to try to make the switch. > > I'm of this view as well, and would go further and say now that modern > graphics developers are working across a wider range of platforms - > OpenGL ES and OpenGL and targeting shader pipelines with other modern > features in the mix for the these developers using the same features > across all the platforms is advantageous, VBO's are very much part of > this mix of modern feature spread across targets while display lists > are very much a hang up old systems. > > > If OSG isn't close to a major > > release, I suggest trying it and seeing if it causes problems. > > Once I get some time to experiment I will have a play with different > datasets and see how I get on. I think we'll need to beef up the > Optimizer to make sure it handles things better. Also plugins also > need updating to create more VBO friendly meshes. To do the job > properly we have to take this all into account, I don't feel just > switching the default is acceptable as it'll lead to some odd > performance drops. > > > As for big vs. small geometries, I used to see differences as well. > > Years ago, my rule of thumb was to make geometries with fewer than 200 > > vertices use display lists and bigger ones use VBOs. I just tested > > this again this morning on NVidia and Intel graphics and I see no > > difference anymore. However, I'm using a practical test scenario that > > runs through a scene in my game with geometries ranging in size from > > about 20 to 1000 vertices. I'm not doing a contrived test. My test > > scene is about 10% faster using all VBOs vs. all display lists. > > For modern scene graphs it's likely that VBO's will be strongest, but > older scene graphs built with triangle strips and small clumps of > geometry will prefer display lists - think OpenFlight databases for an > example where display lists will be strongest. > > Robert. > _______________________________________________ > 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
