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exsprite(3alleg4)


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(3alleg4),      DATAFILE(3alleg4),      END_OF_FUNCTION(3alleg4),
   END_OF_MAIN(3alleg4),  LOCK_FUNCTION(3alleg4),  LOCK_VARIABLE(3alleg4),
   SCREEN_H(3alleg4),      SCREEN_W(3alleg4),      allegro_error(3alleg4),
   allegro_init(3alleg4),     allegro_message(3alleg4),     blit(3alleg4),
   circle(3alleg4),      clear_bitmap(3alleg4),     clear_keybuf(3alleg4),
   create_bitmap(3alleg4), destroy_bitmap(3alleg4),  draw_sprite(3alleg4),
   draw_sprite_h_flip(3alleg4),               draw_sprite_v_flip(3alleg4),
   draw_sprite_vh_flip(3alleg4),      fixed(3alleg4),       font(3alleg4),
   hline(3alleg4),   install_int_ex(3alleg4),   install_keyboard(3alleg4),
   install_sound(3alleg4),    install_timer(3alleg4),     itofix(3alleg4),
   key(3alleg4),        keypressed(3alleg4),       load_datafile(3alleg4),
   makecol(3alleg4),    palette_color(3alleg4),     pivot_sprite(3alleg4),
   pivot_sprite_v_flip(3alleg4),  play_sample(3alleg4), rectfill(3alleg4),
   replace_filename(3alleg4),       rest(3alleg4),        screen(3alleg4),
   set_gfx_mode(3alleg4),    set_palette(3alleg4),   text_height(3alleg4),
   textout_centre_ex(3alleg4), unload_datafile(3alleg4), vsync(3alleg4)



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