Re: [osg-users] VertexBufferObject usage very slow...

Hi Sean, On Tue, Dec 21, 2010 at 5:40 AM, Sean Spicer While digging, it looks like there are several ways to optimize vertex arrays for the caches on various GPUs...have you looked at all at this?  Are there any reasonable rules-of-thumb for organizing the vertex arrays such that they make

Re: [osg-users] VertexBufferObject usage very slow...

Thanks Robert, will do. Happy Holidays! _ Sean Spicer Aqumin (www.aqumin.com) Office+1.713.781.2121 Mobile...+1.713.447.2706 Fax...+1.713.781.2123 On Tue, Dec 21, 2010 at 2:53 AM, Robert Osfield robert.osfi...@gmail.com wrote: Hi

Re: [osg-users] VertexBufferObject usage very slow...

Robert, Wojciech, Thank you for the advice, this is pretty much exactly what I discovered after some further research. This particular code is pretty old, and I've now re-factored it to use indexed tri-sets instead of tri-strips and things are much better. While digging, it looks like there are

Re: [osg-users] VertexBufferObject usage very slow...

Hi Sean, In general when moving from display listed data to VBO's it's best to avoid using tri-strips with separate osg::DrawElements and instead using a single osg::DrawElements containing just GL_TRIANGLES. This will be more duplicated indices but far less overhead in set up and dispatch.

Re: [osg-users] VertexBufferObject usage very slow...

Subject: Re: [osg-users] VertexBufferObject usage very slow... Robert, Some more data... Looks like we're drawing approx 100K tri-strips every frame. The glDrawElements call is the culprit...though I'm still baffled by why it is so much slower with VBOs than in immediate mode. Perhaps the drawing

Re: [osg-users] VertexBufferObject usage very slow...

Hi Sean, I haven't seen any perfomance slow downs with VBO usage. I've been testing the VBO side pretty heavily over the last week, using paged databases that use VBO's. A VBO vertex array of size 65535 is not particularly large at all and shouldn't present any issues. Are you dynamically

Re: [osg-users] VertexBufferObject usage very slow...

Hi Robert, We are not updating the data frame-to-frame, which is why this is so baffling. I'm working through the issue with gDebugger now - if you don't have any suggestions off the top of your head, then I'll start digging and report back what I find, since I don't have time try and duplicate

Re: [osg-users] VertexBufferObject usage very slow...

Robert, Some more data... Looks like we're drawing approx 100K tri-strips every frame. The glDrawElements call is the culprit...though I'm still baffled by why it is so much slower with VBOs than in immediate mode. Perhaps the drawing isn't sorted by VBO so that all of the triangles drawn from

[osg-users] VertexBufferObject usage very slow...

Hi Everyone, Working off the OSG trunk this afternoon, I tried some experiments with VertexBufferObjects and our geometry (all on the fast path). The only deltas in our code are as follows...all timing as measured by OSG stats: geometry-setUseDisplayList(true)