Top id tech drops Doom 3 details

Programmer Robert Duffy discusses system requirements, development woes, and "Ultra" quality.

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Two weeks after Todd Hollenshead used his .plan to announce Doom 3 had gone gold, another id Software staffer has used his own .plan to reveal more details about the game. In a lengthy update, Robert Duffy, one of the primary programmers at id, addresses a variety of subjects, including:

Quality settings: "I've seen quite a few posts in the forums about 'Ultra' quality and why we don't set this by default out of the box. To put things in perspective, most production levels in DOOM 3 contain more media assets than all of Quake 3: Arena...Image fidelity is dependent on what quality level we load the textures at. In Ultra quality, we load each texture; diffuse, specular, normal map, at full resolution with no compression. In a typical DOOM 3 level, this can hover around a whopping 500MB of texture data...due to the hitching that can occur, we chose to require a 512MB video card before setting [Ultra Quality] automatically. High quality uses compression (DXT1,3,5) for specular and diffuse and no compression for normal maps. This looks very, very close to Ultra quality, but the compression does cause some loss. Medium quality uses compression for specular, diffuse, and normal maps. This still looks really, really good, but compressing the normal maps can produce a few artifacts, especially on hard-angled or round edges. This level gets us comfortably onto 128MB video cards. Low quality does everything medium quality does, but it also downsizes textures over 512x512 and we downsize specular maps to 64x64 in this mode as well. This fits us onto a 64MB video card."

ATI vs. Nvidia cards: "One thing of note on the normal map compression is that, generally speaking, if you DXT a normal map you get really crappy results. NVIDIA hardware supports palettized compression, which yields good compression, and normal maps retain hard and round edges really well. Unfortunately, this compression does a poor job in other cases and you end up getting splotchy areas. ATI does not support the palettized compression, so we needed a better solution. ATI had done some research on various methods of normal map compression, and we ended up swapping the red and alpha ( which is zero in the case of a normal map ) channels. This effectively allows the compression to do a much better job and is just one extra instruction in the fragment program to move the alpha channel into the red channel."

Tools used to build Doom 3: "For the curious, here is a list of software/hardware we found useful during the development of DOOM 3: Incredibuild by Xoreax, Visual Assist by Whole Tomato Software, Alienbrain by Avid (formerly NXN), and Visual Studio by Microsoft. The art team used a wide variety of tools (they probably use other stuff too, but this is what comes to mind): Maya, Lightwave, ZBrush, 3D Max, and Photoshop."

Development woes: "We saw a few bumps in the road during the project. We had a multiple (simultaneous) drive failure in our primary development server, which effectively trashed the raid system and was not recoverable. This resulted in building a two-IDE drive raid system on a Saturday morning so the team could keep working. So all of DOOM 3 development was housed in an old development system with a $79 RAID card driving two 100GB drives for about a week. The end result of this was that we went ahead and built two identical RAID 1/0 systems (about a half a terabyte each). This has been the configuration for the last 18 months or so."

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