set_luminance_blender - Enables a luminance blender mode. Allegro game
programming library.
#include <allegro.h>
void set_luminance_blender(int r, int g, int b, int a);
Enables a luminance blender mode for combining translucent or lit
truecolor pixels. Applies the luminance of the source to the
destination. The colour of the destination is not affected.
set_trans_blender(3alleg), drawing_mode(3alleg)