Fog or fade is the effect in which the colors of things and level geometry is modified by distance. There is a global fade color set in MAPINFO with the fade property, but individual sectors can vary. First, sectors with a sky ceiling will use the outsidefog color defined, if any; as will sectors of type 87:Sector_Outside. Secondly, any sector can have its own colored fog set in one of the following three ways:
- In UDMF only: with the fadecolor sector property.
- With a FadeSetter thing placed in the sector.
- With the Sector_SetFade special, which can be used dynamically in a script.
You can use the testfade console command to test a color from within the game.
Fullbright sprites do not appear full bright in fogged sectors.
There is more difference between fogless sectors (fade #000000) and foggy sectors than between the two extremes of dark fog (fade #000001 vs. fade #FFFFFF).
Some additional options are available to the OpenGL renderer.