Sorry, not sorry for the necromancy. The game was mentioned in the Core Decay thread and now I've reinstalled it, so I need help to get the best experience on a modern system. This time I'm going to play the release version, since it's always been the GOTY version before, and I'm aiming for the period authentic experience, not using widescreen or a too high resolution, mods or anything like that.
I've seen you post a lot about Unreal Engine games in the screenshot threat,
schru, so I'm hoping you'll reply. According to kentie.net Deus Ex seems to be stuck in an awkward place where multi-texturing causes some issues, but not enabling it causes others. Can I have my cake and eat it too somehow? Anything else I should be aware of? Is Glide or Direct3D the better option for Deus Ex? Do I use dgVoodoo 2 and if so what settings are the best for Deus Ex?
I can't test the game today, but generally speaking, multitexture had been a feature of the Unreal Engine for over a year by the time Deus Ex came out, so it would have been intended to be used by default, unless someone was still using an older card like the first Voodoo, which didn't support it.
As for whether multitexture causes rendering bugs in DE, I don't think that the comparison screenshots in Kentie's article show that this is the case. While the reflection in the intro with multitexture seems too bright and distinct, the freezer room looks better with it on, as otherwise the mist blends very poorly with the reflective floor.
It probably is the case, as Kentie writes, that Unreal Engine's renderer wasn't sufficiently revised to incorporate the feature without causing some things to look wrong, as we can see in case of the skies in Unreal Tournament.
The release dates of Vooodoo-based cards available on Wikipedia are a bit inconsistent, but it seems that Deus Ex had entered development proper just before Voodoo2 came out, but it lasted for close to a year and a half still after Voodoo3 had been made available. Multitexture was added to the Unreal Engine around the same time. Incidentally, for Direct3D, the game requires DirectX 7.0a, which was released in March 2000, so up-to-date technology was being targeted. Given such a time-line, even apart from the changes made by Epic, Ion Storm had to work without multitexture initially, but then had enough time to make use of and implement it.
I imagine the technique was very useful for performance and it was a standard feature of the very popular Voodoo2 and 3 cards, so I doubt the game could have been intended not to use it. At most, some things just weren't corrected for its operation, but that's just something that has to be accepted. Unfortunately, it's something that occurs fairly regularly when it comes to engine updates.
Maybe one thing worth testing for reference is how the game looks in software, Direct3D, and OpenGL in the original, unpatched renderers and with default settings. I don't know if OpenGL was really included as a fully-featured renderer, as it certainly wasn't on par with Glide in Unreal.
Nvidia's cards running in Direct3D were becoming a valid alternative at the time, but it would be helpful if someone who played games at the time could tell us where things stood, if Voodoo3 was still the standard-setting card for developers or such. After all 3dfx was finished less than half a year from Deus Ex's release date and Nvidia took over its assets.
The original Direct3D renderer can be tested with dgVoodoo, but I'm not sure if it's fully functional even with the wrapper—one obvious sign is whether the gamma or brightness can be adjusted. But from what I recall, the game rendered in it looks kind of bland. One advantage that Nvidia possibly had at the time was that its cards were already capable of rendering in 32-bit colour mode, but someone better informed should confirm this.
It should be possible to disable Multitexture in advanced settings for Direct3D and OpenGL, so as to test how the game looks without it.
The software renderer was definitely intended to present Unreal's visuals faithfully, but I don't know if that was still the case in later games.
Taking all that into account, the settings in dgVoodoo I'd recommend for Deus Ex are as follows:
— first tab: stretched aspect ratio scaling with the C.R.T. filter (or alternatively maybe a better one could be added using a shader injector);
— second tab: Voodoo2 or greater, values appropriate for Voodoo3; resolution Max (matches the monitor's native vertical resolution for 4:3); the gamma ramp should be left on;
— do the same in the third tab, if using Direct3D;
— right-click in the control panel and select the option to reveal additional settings; probably the fifth tab contains dithering settings and the 32-bit output needs to be disabled here; letting the application determine the type of dithering may technically be the more accurate option, but manually-set ordered 4x4 looks much better, especially when it comes to the skies; I doubt that dgVoodoo emulates the dithering performed by Voodoo cards that accurately anyway, as the later cards had multiple settings for it in their drivers and some screenshots of games from the time just look different (see Quake II); let the application decide if using Direct3D because of its 32-bit capability;
— if you have problems with the mouse being stuck in the top-right corner in the Direct3D renderer, tick a box relating to mouse behaviour in the fourth tab.
Now, for the game itself, the Glide renderer should be selected in the pop-up window on launching the game. There's also the matter of hardware-accelerated 3-D sound. The best option is owning a real A3D card, while the basic functionality of DirectSound and EAX can be emulated with Creative's ALchemy.
Once in the menu, press T, remove the ‘Say’ command, and enter
preferences. This brings up advanced settings where it's possible to verify that Glide or Direct3D have all their features on, or that hardware sound is configured correctly (surround sound is for Dolby Digital receivers).
As for the resolution, judging by the scale of the HUD, 640x480 was the default, but there are promotional screenshots taken at a resolution slightly above 1024x768. Setting a low resolution in combination with dgVoodoo rendering the game at a higher resolution preserves the UI's proportions from lower resolutions for which it was designed.