exalpha - Creating and using 32 bit RGBA sprites. Allegro game programming library.

       This  program  demonstrates  how  to use the 32 bit RGBA translucency functions to store an alpha channel
       along with a bitmap graphic.  Two images are loaded from disk. One will be used for  the  background  and
       the  other as a sprite. The example generates an alpha channel for the sprite image, composing the 32 bit
       RGBA bitmap during runtime, and draws it at the position of the mouse cursor.

       exalpha - Creating and using 32 bit RGBA sprites. Allegro game programming library.

BITMAP(3alleg4),  END_OF_MAIN(3alleg4),  SCREEN_H(3alleg4),  SCREEN_W(3alleg4),   allegro_error(3alleg4),
       allegro_init(3alleg4),        allegro_message(3alleg4),       blit(3alleg4),       clear_keybuf(3alleg4),
       create_bitmap(3alleg4),   destroy_bitmap(3alleg4),   draw_trans_sprite(3alleg4),   drawing_mode(3alleg4),
       font(3alleg4), getb(3alleg4), getg(3alleg4), getpixel(3alleg4), getr(3alleg4), install_keyboard(3alleg4),
       install_mouse(3alleg4),      install_timer(3alleg4),      keypressed(3alleg4),      load_bitmap(3alleg4),
       makecol(3alleg4),    mouse_x(3alleg4),    mouse_y(3alleg4),     putpixel(3alleg4),     rectfill(3alleg4),
       replace_filename(3alleg4),  screen(3alleg4),  set_alpha_blender(3alleg4),  set_color_conversion(3alleg4),
       set_color_depth(3alleg4),              set_gfx_mode(3alleg4),              set_multiply_blender(3alleg4),
       set_write_alpha_blender(3alleg4), solid_mode(3alleg4), stretch_blit(3alleg4), textprintf_ex(3alleg4)

Allegro                                           version 4.4.3                                 exalpha(3alleg4)

#include<allegro.h>Exampleexalpha