man set_invert_blender () - Enables an invert blender mode. Allegro game programming library.
NAME
set_invert_blender - Enables an invert blender mode. Allegro game programming library.
SYNOPSIS
#include <allegro.h>
void set_invert_blender(int r, int g, int b, int a);
DESCRIPTION
Enables an invert blender mode for combining translucent or lit truecolor pixels. Blends the inverse (or negative) colour of the source with the destination.