fade_from - Man Page

#include <allegro.h>

void fade_from(const PALETTE source, const PALETTE dest, int speed);

Fades gradually from the source palette to the dest palette. The speed is  from 1 (the slowest) up to 64 (instantaneous).

Note that this function will block your game while the fade is in effect, and it won't work right visually if you are not in an 8 bit color depth resolution.

fade_in(3), fade_out(3), fade_interpolate(3), fade_from_range(3)

fade_from_range(3), fade_in(3), fade_interpolate(3), fade_out(3).