FadeRange
From ZDoom Wiki
void faderange (int red1, int green1, int blue1, fixed amount1, int red2, int green2, int blue2, fixed amount2, fixed seconds);
Usage
Faderange sets the current flash to the first one you pass it and then fades it to the second flash over the specified number of seconds.
Examples
script 1 (void)
{
// fade from 80% green to 80% blue in two seconds
faderange (0, 255, 0, 0.8, 0, 0, 255, 0.8, 2.0);
}

