Hi
Well, i just tested how to setup my engine, to get the best performance out of it.
I then enabled alpha-testing. From earlier tests i knew, that it is for free.
Now i rendered flat polys, no texturing, no blending and stuff.
I don´t have any polys/pixels, that get filtered out by the alpha-test, but i didn´t expect a hit, because of my previous experience.
Now i enabled it, with AlphaFunc set to
GL_GEQUAL/0.95
and my FPS dropped from 270 to 220 !!!
At the moment i render around 3000 triangles per frame, in one (or two) calls, with VBO.
Could it be, that alphatest works only for free, when texturing is enabled? nVidia said, that they can render flat polys with twice the speed of textured ones. Could it be, that they dropped alpha-test support for them to speed it up a bit more, since it doesn´t make much sense to use alpha-test for flat polys, at all?
I am just curious. I don´t need alpha-testing for flat polys (who does?), but now i know to make sure to DISABLE it, when rendering without textures.
And another thing: Can anyone tell me, what dithering is good for? I could not find any translation for that word, and i could not find any description, what effect dithering gives, when it is enabled (except for some speed penalty).
BTW: I am running on WinXP, a GF Ti 4200 and the 44.03 drivers.
Thanks,
Jan.