exsprite(3)                     Allegro manual                     exsprite(3)



NAME
       exsprite - Datafiles access and sprite animation. Allegro game
       programming library.

SYNOPSIS
       #include <allegro.h>


       Example exsprite

DESCRIPTION
       This example demonstrates how to use datafiles, various sprite drawing
       routines and flicker-free animation.

       Why is the animate() routine coded in that way?  As you probably know,
       VIDEO RAM is much slower than "normal" RAM, so it's advisable to reduce
       VRAM blits to a minimum.  Drawing sprite on the screen (meaning in
       VRAM) and then clearing a background for it is not very fast. This
       example uses a different method which is much faster, but require a bit
       more memory.

       First the buffer is cleared (it's a normal BITMAP), then the sprite is
       drawn on it, and when the drawing is finished this buffer is copied
       directly to the screen. So the end result is that there is a single
       VRAM blit instead of blitting/clearing the background and drawing a
       sprite on it.  It's a good method even when you have to restore the
       background. And of course, it completely removes any flickering effect.

       When one uses a big (ie. 800x600 background) and draws something on it,
       it's wise to use a copy of background somewhere in memory and restore
       background using this "virtual background". When blitting from VRAM in
       SVGA modes, it's probably, that drawing routines have to switch banks
       on video card. I think, I don't have to remind how slow is it.

       Note that on modern systems, the above isn't true anymore, and you
       usually get the best performance by caching all your animations in
       video ram and doing only VRAM->VRAM blits, so there is no more
       RAM->VRAM transfer at all anymore. And usually, such transfers can run
       in parallel on the graphics card's processor as well, costing virtually
       no main cpu time at all.  See the exaccel example for an example of
       this.


SEE ALSO
       BITMAP(3), DATAFILE(3), END_OF_FUNCTION(3), END_OF_MAIN(3),
       LOCK_FUNCTION(3), LOCK_VARIABLE(3), SCREEN_H(3), SCREEN_W(3),
       allegro_error(3), allegro_init(3), allegro_message(3), blit(3),
       circle(3), clear_bitmap(3), clear_keybuf(3), create_bitmap(3),
       destroy_bitmap(3), draw_sprite(3), draw_sprite_h_flip(3),
       draw_sprite_v_flip(3), draw_sprite_vh_flip(3), fixed(3), font(3),
       hline(3), install_int_ex(3), install_keyboard(3), install_sound(3),
       install_timer(3), itofix(3), key(3), keypressed(3), load_datafile(3),
       makecol(3), palette_color(3), pivot_sprite(3), pivot_sprite_v_flip(3),
       play_sample(3), rectfill(3), replace_filename(3), rest(3), screen(3),
       set_gfx_mode(3), set_palette(3), text_height(3), textout_centre_ex(3),
       unload_datafile(3), vsync(3)



Allegro                          version 4.2.3                     exsprite(3)
