Sector_SetFade

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213:Sector_SetFade (tag, r, g, b)

tag: Tag of affected sector 
r: Amount of red to fade to 
g: Amount of green to fade to 
b: Amount of blue to fade to 

Sets the color that light in the tagged sectors fade to as they get further away from the viewer. This will give the sector a 'fog' effect and can greatly enhance the mood of a level. By default, this is whatever the level's fade is specified as being in a MAPINFO lump, or black, if it doesn't specify a fade. The note about changing a sector's color during the middle of gameplay also applies here. You can use the testfade console command to test a fade from within the game. Keep in mind that Sector_SetFade is affected by a sector's light, so a faded sector with a light value of 255 will have virtually no visible fade color, and a faded sector with a light value of 0 will be nearly a solid color.