http://bugs.winehq.org/show_bug.cgi?id=13225
--- Comment #9 from Alexander Dorofeyev alexd4@inbox.lv 2008-05-23 16:42:16 --- Can someone confirm the hack is working, especially if so on non-nvidia hardware?
The frustrating thing about this bug is that as far as I can tell this hack shouldn't make any difference by OpenGL 2.1 specs, because specification suggests that alpha reference and fragment alpha are rounded to integers for the purpose of comparison. I could understand the difference if it was doing something like floor(), but if it's rounded then 1/255 and 1/255 + some very small value shouldn't make difference. But it does, on my machine at least. I would otherwise say it's a driver bug, but it's happening on nvidia, which usually has a very correct opengl and also on other hardware, so maybe I'm not reading specs right.
Another strange thing about it is I can't reproduce it in a test. The basic functionality usually seems to work, but there must be something else in the program that triggers it.