Descent and Descent II do indeed use a quad-based engine, at least for the environments. This allowed the engine to easily determine which quads were visible based on if a connecting quad surface was being rendered or not, and thus which objects to render based on what quads they were presently inside. It was a highly streamlined way to ensure that only visible areas got rendered given an environment that allowed movement and level design in all directions, plus when you use a level editor for Descent or Descent II, once you get used to the quad-based system you'd be surprised how quickly you can put stuff together. ;)
As for the enemy polygon counts, and whether or not they're using quads instead of triangles, I'm not sure. Best guess is that the average enemy has 60 to 100 triangles, or a little more than half of that if quads.
The Descent II engine IS actually slightly modified from the original. The major difference is world-based dynamic light sources, since in Descent II you could change the lighting of the world by destroying light-emitting surfaces. Descent II also added new interactions like the ability to unlock/open doors by shooting switches. The engine is also more optimized in Descent II and can hit higher framerates for the same rendering complexity, especially in SVGA video modes. Other than that, they're almost identical and most level editors for these games can handle both Descent and Descent II levels.
However, while Descent was ahead of its time in terms of rendering quality, Quake did add a lot of tech to the mix that made it much easier to mod among other things, plus let's face it, the Descent games are VERY difficult in comparison to Quake and are more difficult to control, so it's no wonder more people refer to Quake for advancing gaming tech over the Descent series.
--- Kris Asick (Gemini)
--- Pixelmusement Website: www.pixelships.com
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