snide on 14/4/2009 at 16:21

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I have Thief: TDP up and running smoothly w/ videos on both a 32-bit XP SP3 PC and a Vista SP1 64-bit PC :D. Both PCs use nVidia GPUs (XP = 6600GT @ 1680X1050 and Vista = 8600GT @ 1920X1200). ddfix and the widescreen patches have been applied. In the ddfix.ini I changed AnisotropicFiltering=1 and have Anisotropic filtering forced to 16x in the drivers. The game runs great at these settings. The slowdowns occur when forcing Anti-aliasing; anything over 4x causes stuttering. Fortunately, that stuttering is eliminated when I turn off the Z-buffer option in the video settings in the game (on the Vista PC I've had 8x AA enabled). Unfortunately, that setting reverts back to ON whenever the menu is accessed again (to Save, or reload the game, for example). Am I the only one that can't get that setting to stick, or does someone have a solution for that issue? NOTE: changing the z-buffer setting in ddfix.ini has no effect.

Hiatus on 22/4/2009 at 18:18

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ok. I've got ATI X19xx and with ddfix 1.2+ (which utilises D3D6) I *also* got stuterring/slowdowns/lower fps when I set AA to > 4x (only 6x in my case). AA:4x and lower are fine. AF even maxxed is fine, too.

With vanilla Thief (no ddfix) and with ddfix 1.1 (which uses D3D9) fps with AA over 4x is fine.

Conlusion and *possible* explanation: ddfix 1.2+ is more h/w hungry and with our cards AA over 4x is just too slow (would be nice if someone with more powerful card check it). Don't don't if it's fixable or not. It's probably due to ddfix 1.2+ (D3D6) stressing Z buffer of the card much more than vanilla version/D3D9 version, doing necessary operations behind the scenes. Or maybe drivers for D3D6 are not optimized enough for such thing (or ddfix itself could be optimized better in this regard - maybe it does sth that kills performace with high AA modes). Who know - only Timeslip could investigate it and possibly fix it, but he seems to have lost interest in ddfix completely :(.

Anyway, I already noticed this issue and notitied Timeslip about it last year (about 1 year ago) about it (you can even find my post about it in that long ddifx thread). AFAIR no response/explanation of that from Timeslip.

if you can, check it out with more poweful, DX10 class card.

edit: just read you have this issue with TDP. My problem was with T2 (TDP runs fine with AA >4x for me with ddfix, AFAIR because it's MUCH less hardware power hungry. Will need to recheck it, though). Plus you run in pretty high res (= perf. hit).

Anyway, for me it was not that big an issue, as AA 4x looks pretty good already.

Newer cards (DX9 class and higher) from Nvidia have very poor support for older DX apps anyway, so perf. problems might be well due to this (they only care about new stuff). Their DX10 class cards are really awful in this regard (lots of low fps problems in many older games). So it's possible their D3D6 (and similar) optimizations in the drivers are broken/removed (hence problems with AA perf. etc.)

bikerdude on 22/4/2009 at 22:13

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Im not entirely sure what your problem is Snide, are you saying that the AA settings wont stay on the setting you choose..? I have noticed that the most recent nvidia drivers wont enable AA in thief/ddfix etc below 4xAA. And with regard to using more than 4x on the card you have is not recommended as they are just not powerfull enough at that resolution with ddfix (ddfix is a bit of a gpu hog)