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View Full Version : Disabling multisampling is impossible?



Cheps
08-10-2004, 03:05 AM
I made an empty scene, and I was kinda surprised to only have 120 fps. After searching for a while I found out that it was a multisampling problem. When multisampling is off(in my drivers settings) I have 700 fps, but when it is enabled it goes down to 120 fps.

When I use glDisable(GL_MULTISAMPLE_ARB), the effect doesn't show anymore on screen(tested it with a single triangle in my scene), but I still have 110 fps, is this normal?

Also I use GLUT, and it doesn't change anything if I use GLUT_MULTISAMPLE or not with glutInitDisplayMode(). Multisampling is always enabled even without it. Again, is this normal?

So it seems to me that if multisampling is enabled in my drivers settings, my max fps will be 120, even if GL_MULTISAMPLE_ARB is disabled and it's an empty scene that is not using multisampling at all???

Relic
08-10-2004, 03:35 AM
Driver settings override you application requests. I'm astonished that you could disable multisampling with the driver enforcing it.
Disabling multisampling is not the same as choosing a single-sampled pixelformat.
The process which brings the multisample buffer to the display is what costs your time.
With driver settings to no FSAA, test your application while requesting a multisample buffer and while not, you get the hit in the first case.
That's to be expected, in either multisample pixelformats chosen by the app or enforced by the driver settings and performance depends on the fillrate of the chip.