DOKK / manpages / debian 11 / allegro4-doc / set_invert_blender.3alleg4.en
set_invert_blender(3alleg4) Allegro manual set_invert_blender(3alleg4)

set_invert_blender - Enables an invert blender mode. Allegro game programming library.

#include <allegro.h>

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

Enables an invert blender mode for combining translucent or lit truecolor pixels. Blends the inverse (or negative) colour of the source with the destination.

set_trans_blender(3alleg4), drawing_mode(3alleg4)

version 4.4.3 Allegro