extrans(3alleg4)                 Allegro manual                 extrans(3alleg4)

       extrans - Lighting and translucency effects. Allegro game programming

       #include <allegro.h>

       Example extrans

       This program demonstrates how to use the lighting and translucency
       functions. The first part of the example will show a dark screen
       illuminated by a spotlight you can move with your mouse. After a key
       press the example shows the full bitmap and the spotlight changes to be a
       reduced version of the background with 50% of translucency.

       The translucency effect is easy to do in all color depths.  However, the
       lighting effect has to be performed in a different way depending on
       whether the screen is in 8bit mode or another color depth. This is
       because additive drawing mode uses a different set of routines for
       truecolor modes.

       BITMAP(3alleg4), COLOR_MAP(3alleg4), END_OF_MAIN(3alleg4),
       PALETTE(3alleg4), RGB(3alleg4), RGB_MAP(3alleg4), SCREEN_H(3alleg4),
       SCREEN_W(3alleg4), allegro_error(3alleg4), allegro_init(3alleg4),
       allegro_message(3alleg4), bitmap_color_depth(3alleg4), blit(3alleg4),
       circlefill(3alleg4), clear_bitmap(3alleg4), clear_keybuf(3alleg4),
       color_map(3alleg4), create_bitmap(3alleg4), create_bitmap_ex(3alleg4),
       create_light_table(3alleg4), create_rgb_table(3alleg4),
       create_trans_table(3alleg4), destroy_bitmap(3alleg4),
       draw_trans_sprite(3alleg4), drawing_mode(3alleg4),
       install_keyboard(3alleg4), install_mouse(3alleg4),
       install_timer(3alleg4), keypressed(3alleg4), load_bitmap(3alleg4),
       mouse_x(3alleg4), mouse_y(3alleg4), poll_mouse(3alleg4),
       rectfill(3alleg4), replace_filename(3alleg4), rest(3alleg4),
       rgb_map(3alleg4), screen(3alleg4), set_alpha_blender(3alleg4),
       set_gfx_mode(3alleg4), set_palette(3alleg4), set_trans_blender(3alleg4),
       set_write_alpha_blender(3alleg4), stretch_blit(3alleg4)

Allegro                           version 4.4.3                 extrans(3alleg4)