man extrans () - Lighting and translucency effects. Allegro game programming library.
NAME
extrans - Lighting and translucency effects. Allegro game programming library.
SYNOPSIS
#include <allegro.h>
Example extrans
DESCRIPTION
This program demonstrates how to use the lighting and translucency functions. The first part of the example will show a dark screen iluminated by a spotlight you can move with your mouse. After a keypress 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.
SEE ALSO
BITMAP(3alleg), COLOR_MAP(3alleg), END_OF_MAIN(3alleg), PALETTE(3alleg), RGB(3alleg), RGB_MAP(3alleg), SCREEN_H(3alleg), SCREEN_W(3alleg), allegro_error(3alleg), allegro_init(3alleg), allegro_message(3alleg), bitmap_color_depth(3alleg), blit(3alleg), circlefill(3alleg), clear_bitmap(3alleg), clear_keybuf(3alleg), color_map(3alleg), create_bitmap(3alleg), create_bitmap_ex(3alleg), create_light_table(3alleg), create_rgb_table(3alleg), create_trans_table(3alleg), destroy_bitmap(3alleg), draw_trans_sprite(3alleg), drawing_mode(3alleg), install_keyboard(3alleg), install_mouse(3alleg), install_timer(3alleg), keypressed(3alleg), load_bitmap(3alleg), mouse_x(3alleg), mouse_y(3alleg), poll_mouse(3alleg), rectfill(3alleg), replace_filename(3alleg), rgb_map(3alleg), screen(3alleg), set_alpha_blender(3alleg), set_gfx_mode(3alleg), set_palette(3alleg), set_trans_blender(3alleg), set_write_alpha_blender(3alleg), stretch_blit(3alleg)