set_write_alpha_blender(3) Allegro manual set_write_alpha_blender(3)NAMEset_write_alpha_blender - Enables the special alpha-channel editing
mode. Allegro game programming library.
SYNOPSIS
#include <allegro.h>
void set_write_alpha_blender();
DESCRIPTION
Enables the special alpha-channel editing mode, which is used for draw‐
ing alpha channels over the top of an existing 32-bit RGB sprite, to
turn it into an RGBA format image. After calling this function, you can
set the drawing mode to DRAW_MODE_TRANS and then write draw color val‐
ues (0-255) onto a 32-bit image. This will leave the color values
unchanged, but alter the alpha to whatever values you are writing.
After enabling this mode you can also use draw_trans_sprite() to super‐
impose an 8-bit alpha mask over the top of an existing 32-bit sprite.
SEE ALSOset_alpha_blender(3), draw_trans_sprite(3), drawing_mode(3), exal‐
pha(3), extrans(3)Allegro version 4.4.2 set_write_alpha_blender(3)