debian man page for set_screen_blender

set_screen_blender(3alleg4)					  Allegro manual				       set_screen_blender(3alleg4)

NAME
       set_screen_blender - Enables a screen blender mode. Allegro game programming library.

SYNOPSIS
       #include <allegro.h>

       void set_screen_blender(int r, int g, int b, int a);

DESCRIPTION
       Enables	a  screen blender mode for combining translucent or lit truecolor pixels. This blender mode lightens the colour of the destination
       image by multiplying the inverse of the source and destination colours. Sort of like the opposite of the multiply blender mode.

SEE ALSO
       set_trans_blender(3alleg4), drawing_mode(3alleg4)

Allegro 							   version 4.4.2				       set_screen_blender(3alleg4)