set_alpha_blender - Enables a special alpha-channel blending mode. Allegro game
programming library.
#include <allegro.h>
void set_alpha_blender();
Enables the special alpha-channel blending mode, which is used for drawing
32-bit RGBA sprites. After calling this function, you can use
draw_trans_sprite() or draw_trans_rle_sprite() to draw a 32-bit source image
onto any hicolor or truecolor destination. The alpha values will be taken
directly from the source graphic, so you can vary the solidity of each part of
the image. You can't use any of the normal translucency functions while this
mode is active, though, so you should reset to one of the normal blender modes
(eg. set_trans_blender()) before drawing anything other than 32-bit RGBA
sprites.
set_trans_blender(3), draw_trans_sprite(3),
draw_trans_rle_sprite(3), set_write_alpha_blender(3),
exalpha(3), exrotscl(3), extrans(3)