set_multiply_blender(3) - Linux man page
Name
set_multiply_blender - Enables a multiply blender mode. Allegro game programming library.
Synopsis
#include <allegro.h>
void set_multiply_blender(int r, int g, int b, int a);
Description
Enables a multiply blender mode for combining translucent or lit truecolor pixels. Combines the source and
destination images, multiplying the colours to produce a darker colour. If a colour is multiplied by white it remains unchanged; when multiplied by black it
also becomes black.
See Also
set_trans_blender(3), drawing_mode(3), exalpha(3)