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

       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.

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

set_trans_blender(3alleg4), drawing_mode(3alleg4)

Allegro                                           version 4.4.3                      set_screen_blender(3alleg4)

#include<allegro.h>voidset_screen_blender(intr,intg,intb,inta);