Provided by: liballegro-doc_4.2.2-3_all bug

NAME

       request_video_bitmap  -  Triple  buffering  page  flip  request.  Allegro game programming
       library.

SYNOPSIS

       #include <allegro.h>

       int request_video_bitmap(BITMAP *bitmap);

DESCRIPTION

       This function is used for triple buffering.  It  requests  a  page  flip  to  display  the
       specified  video bitmap object, but returns immediately rather than waiting for a retrace.
       The flip will then take place during the next vertical  retrace,  but  you  can  carry  on
       running  other  code  in the meantime and use the poll_scroll() routine to detect when the
       flip has actually taken place. Triple buffering is only possible on certain hardware:  see
       the comments about request_scroll(). Example:

          int current_page;
          BITMAP *video_page[3];
          ...
          /* Create pages for page flipping */
          video_page[0] = create_video_bitmap(SCREEN_W, SCREEN_H);
          video_page[1] = create_video_bitmap(SCREEN_W, SCREEN_H);
          video_page[2] = create_video_bitmap(SCREEN_W, SCREEN_H);
          current_page = 0;
          ...
          /* draw the screen and flip pages */
          draw_screen(video_page[current_page]);
          do {
          } while (poll_scroll());
          request_video_bitmap(video_page[current_page]);
          current_page = (current_page+1)%3;
          ...

RETURN VALUE

       Returns zero on success and non-zero on failure.

SEE ALSO

       poll_scroll(3alleg),           request_scroll(3alleg),           gfx_capabilities(3alleg),
       create_video_bitmap(3alleg), scroll_screen(3alleg), ex3buf(3alleg), exupdate(3alleg)