set_luminance_blender - Man Page

#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(3), drawing_mode(3)

set_trans_blender(3).