http://bugs.winehq.org/show_bug.cgi?id=14038
--- Comment #53 from Alexander Dorofeyev alexd4@inbox.lv 2008-07-24 15:03:39 --- My experiences with current git (all details / effects on high, no antialiasing and no triple buffering, card geforce 6100):
1) I see no problems with bullet time or with screen cropping in either backbuffer or fbo. Everything looks ok with the exception of known bugs - shadow and character lightening.
2) Performance with fbo - very bad indeed. I have these 0.5-1 sec freezes like every second or so, between them everything is relatively smooth. I know my card isn't a gaming powerhouse, but I see nothing like that in backbuffer mode. FBO mode is several times worse because of these stalls all the time, kinda strange as it's supposed to be faster (?). I think I have also experienced a similar annoyance in HL2 / fbo (need to retest, I didn't compare it to backbuffer there).
3) Henri's patch makes GL_INVALID_ENUM message go away, but another message starts to appear as Tobias also mentions (Reading back render target but SFLAG_INDRAWABLE not set). Doesn't seem to change much else. Performance stays as it was too. Could it be that these older cards just suck at supporting fbo?
So all of the rendering issues appear to be specific to geforce 5 (5 and below?) series.