What is table fog and what difference does it make in visuals?

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What is table fog and what difference does it make in visuals?

Postby Dragonslayer182 » 2019-7-10 @ 07:58

I've recently been trying to decide on a GPU for the Athlon XP Win98SE build I made a thread about a few days ago. I've been looking around and I keep hearing about table fog. I tried to look it up online, but the only thing I found that was relevant was a vogons thread that explained a bit, but what I really want to know is how much of a visual difference it makes. Are there any pictures or videos that show the difference between a game running on a card with and without table fog support?
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Re: What is table fog and what difference does it make in visuals?

Postby Scali » 2019-7-10 @ 08:45

Table fog is also known as 'pixel fog' (https://docs.microsoft.com/en-us/window ... /pixel-fog), where the alternative is 'vertex fog' (https://docs.microsoft.com/en-us/window ... vertex-fog).

So it's somewhat like per-pixel lighting vs per-vertex lighting.
Per-pixel allows more detail, but how much of a visual impact that actually has, depends on how a game uses it.
I wouldn't know of a game that can use both pixel fog and vertex fog off the top of my head, so I wouldn't know an example to compare the two.

I would say that the difference is probably not that large in practice. Firstly, because in the days of fixed-function fog, the geometry didn't have that much detail anyway, so trying to add detailed fog to undetailed geometry doesn't really work. Secondly, because there was not a lot of per-pixel lighting being used at all, if any, in those days.
Once you start using shaders for per-pixel lighting, you can also create your own custom fog routines, so you would no longer rely on table fog anyway.
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Re: What is table fog and what difference does it make in visuals?

Postby leileilol » 2019-7-10 @ 19:22

There's a lot of depth to this subject :)


Generally when a card doesn't support table fog properly, it may either skip the fog or render nothing entirely. Usually this affects several Direct3D6 games just before the turn of the millenium.
by the way, DOSBox is not for running Windows 9x
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