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Labman



Joined: 05 Nov 2004
Posts: 51
Location: Brisbane, Australia

PostPosted: Fri Oct 09, 2009 3:14 am    Post subject: Bad extension support Reply with quote

Why say you support VBO but then don't actually support the function use.

When I use the glGenBuffers it just returns 0 which means no buffer. Nice work VIA, you guys are awesome!
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reckless



Joined: 24 Jan 2008
Posts: 390
Location: inside tha debugger

PostPosted: Fri Oct 09, 2009 4:50 am    Post subject: Reply with quote

heh funny that you mention it i actually had the same experience a while back with the same function. actually in something as old as phoenix quake.

even the newest compiler on the newest platform os tells me that this function is null and void Laughing
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Labman



Joined: 05 Nov 2004
Posts: 51
Location: Brisbane, Australia

PostPosted: Tue Oct 13, 2009 4:35 am    Post subject: Reply with quote

Now its returning a valid buffer id but it segfaults when it tries to render the vbo Sad
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Spike



Joined: 05 Nov 2004
Posts: 944
Location: UK

PostPosted: Tue Oct 13, 2009 9:16 am    Post subject: Reply with quote

What happens if you use self-chosen ids?
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Labman



Joined: 05 Nov 2004
Posts: 51
Location: Brisbane, Australia

PostPosted: Fri Oct 30, 2009 8:27 pm    Post subject: Reply with quote

Just thought I should say that I was a bit quick to blame S3 here, was some weird stuff caused by the automatic opengl extension loading lib I was using. That and glBufferData and glBufferDataARB are not the same function. One works and one doesn't.

I've got it all working now but I didn't get any speedup from it Sad
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mh



Joined: 12 Jan 2008
Posts: 909

PostPosted: Fri Oct 30, 2009 9:04 pm    Post subject: Reply with quote

Labman wrote:
Just thought I should say that I was a bit quick to blame S3 here, was some weird stuff caused by the automatic opengl extension loading lib I was using. That and glBufferData and glBufferDataARB are not the same function. One works and one doesn't.

I've got it all working now but I didn't get any speedup from it Sad

Are you locking and refilling it every frame? That's not good for VBOs, for the same reason as texture uploads during runtime aren't good. What you need is one single big VBO containing all of your static geometry (verts and texcoords don't change), then render each visible surfs from the surfs offset in that. Everything else needs to be done without a VBO. Even with the most optimal strategy (including use of shaders for any texcoord modification you do), a hardware VBO will only give about 10% speedup on Quake owing to the BSP architecture, so it's probably not worth it. Other apps with different architectures may give better or worse results.
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Labman



Joined: 05 Nov 2004
Posts: 51
Location: Brisbane, Australia

PostPosted: Sat Oct 31, 2009 11:04 pm    Post subject: Reply with quote

I upload the VBO once at the start of the application, I think that the lack of dedicated graphics memory is more likely the reason for no speed ups however.
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mh



Joined: 12 Jan 2008
Posts: 909

PostPosted: Sun Nov 01, 2009 12:00 am    Post subject: Reply with quote

Labman wrote:
I upload the VBO once at the start of the application, I think that the lack of dedicated graphics memory is more likely the reason for no speed ups however.

Yeah, that would be correct. I've found the same in D3D. It's only really worthwhile on a hardware T&L card, and only really usable if you can modify verts and texcoords using shaders (otherwise you're stuck with totally static and scrolling textures, water warps, and suchlike won't work at all).
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