OpenGL accumulation buffer is very slow, testing needed

[Dmitry Marakasov]

* Dmitry Marakasov (amdmi3 at amdmi3.ru) wrote:

Thanks for all who send me their results. Well, the problem actually
only shows itself on my (read: old) hardware. May still be a bug
in drivers, as the accumulation buffer test runs faster in software
rendering, but there's nothing FreeBSD-specific, and this doesn't
affect users of newer hardware, so nothing to worry about.

Here are the results for the history:

My hardware (1000x performance drop due to unsupported and probably
not properly emulated accumulation buffer):

OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce3/AGP/SSE2
OpenGL version string: 1.5.8 NVIDIA 96.43.05

--- FreeBSD:
./without_accum
Seconds: 20.00, frames: 10306, FPS: 515.299
./with_accum
Seconds: 20.12, frames: 10, FPS: 0.497
--- Linux:
./without_accum
Seconds: 20.00, frames: 11304, FPS: 565.170
./with_accum
Seconds: 20.65, frames: 11, FPS: 0.533
---

Other results:
(note: don't worry about 4-5x FPS drop. It just means that accumulation
buffer stuff is up to 5x slower than rendering a quad 4 times. Since
real scenes render tens of thousands polygons, accumulation buffer takes
no significant time actually).

--- FreeBSD:
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce 7600 GS/PCI/SSE2/3DNOW!
OpenGL version string: 2.1.2 NVIDIA 169.12

./without_accum
Seconds: 20.00, frames: 23890, FPS: 1194.486
./with_accum
Seconds: 20.00, frames: 5236, FPS: 261.775
--- FreeBSD:
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce 8600 GT/PCI/SSE2
OpenGL version string: 2.1.2 NVIDIA 169.12

./without_accum
Seconds: 20.00, frames: 25021, FPS: 1251.017
./with_accum
Seconds: 20.00, frames: 5358, FPS: 267.890
--- FreeBSD:
GeForce 7300 GS

./without_accum
Seconds: 0.05, frames: 17, FPS: 347.897
./with_accum
Seconds: 0.50, frames: 15, FPS: 29.906
--- Linux:
GeForce 7300 Go

./without_accum
Seconds: 128.00, frames: 38744, FPS: 302.688
./with_accum
Seconds: 128.00, frames: 12830, FPS: 100.234
---

-- 
Dmitry A. Marakasov    | jabber: amdmi3 at jabber.ru
amdmi3 at amdmi3.ru       | http://www.amdmi3.ru