From ZDoom Wiki
void FadeTo (int red, int green, int blue, fixed amount, fixed seconds);
Fades the activator's view from the current palette flash to another one. This will also work if the activator is looking through another viewpoint. (Using a camera, etc)
- red: Amount of red in the flash from 0-255.
- green: Amount of green in the flash from 0-255.
- blue: Amount of blue in the flash from 0-255.
- amount: Intensity of the flash from 0-1.0.
- seconds: Time needed to complete the fade in seconds.