extrans(3)

✨ extrans(3) — the Allegro manual's lil' glow-up demo ✨

okay bestie, so this one is a page from the Allegro manual, and it's all about extrans — the lighting and translucency effects situation. 💡✨ Allegro game programming library, periodt.

🌸 SYNOPSIS 🌸

#include <allegro.h>

Example extrans

💖 DESCRIPTION 💖

So this program is literally a demo of how to use the lighting and translucency functions, and it's giving main character energy from start to finish. 🫶

Part one: you get a dark screen, right? Total void. And then a spotlight illuminates it, and you can move that spotlight around with your mouse. 🖱️✨ Obsessed.

Part two: after a key press, the example switches it up and shows you the full bitmap, and the spotlight transforms — it becomes a reduced version of the background with 50% of translucency. 💅 The glow-up is real.

Now for the technical tea, and this part matters so don't scroll past it:

• The translucency effect is easy to do in all color depths. No cap, all of them. 🎀
• But the lighting effect has to be performed in a different way depending on whether the screen is in 8bit mode or another color depth. ⚠️

And why, you ask? Because additive drawing mode uses a different set of routines for truecolor modes. That's the whole reason. iykyk. 🌈

👑 SEE ALSO 👑

The whole friend group, fr fr — every single one of them:

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

and that's the whole page, bestie 🦋 this one came from the Allegro manual, version 4.4.3 — mwah, iconic, no notes. 💜🎀