Kahenraz wrote on 2022-07-07, 02:15:
It's strange that this is such an intermittent issue. With the need to use different tricks to optimize for FPS by use of draw distance, I would have thought that fog would be a first-class citizen of a feature.
From what I've seen, it's true that fog was mostly used to reduce draw distance during the early days of 3D acceleration, especially for games which were ported from consoles like Shadows of the Empire. However, in the following years, developers started using fog to enhance the atmosphere of games, rather than as a way to improve frame rate. Thief 2 and NFS: High Stakes are good examples of this.
Can someone explain why it's so intermittent or problematic across vendors and drivers?
3DFX cards supported table fog out of the box, and those were by far the most popular 3D accelerators early on. This likely led game developers to focus on table fog at that time. In consequence, this caused other hardware manufacturers like Nvidia and Matrox to support table fog as well.
And why, even on the same card, it may work in some but not all games?
There are different types of fog implementation. You can read about those here and also here. Some games only used table fog and, if that wasn't supported by your hardware, the effect simply wasn't rendered. Other games may have used different fog implementations and/or had a fallback mechanism.