set_gfx_mode(3)                 Allegro manual                 set_gfx_mode(3)



NAME
       set_gfx_mode - Sets a graphic video mode. Allegro game programming
       library.

SYNOPSIS
       #include <allegro.h>


       int set_gfx_mode(int card, int w, int h, int v_w, int v_h);

DESCRIPTION
       Switches into graphics mode. The card parameter should usually be one
       of the Allegro magic drivers (read introduction of chapter "Graphics
       modes") or see the platform specific documentation for a list of the
       available drivers. The w and h parameters specify what screen
       resolution you want.  The color depth of the graphic mode has to be
       specified before calling this function with set_color_depth().

       The v_w and v_h parameters specify the minimum virtual screen size, in
       case you need a large virtual screen for hardware scrolling or page
       flipping. You should set them to zero if you don't care about the
       virtual screen size.

       When you call set_gfx_mode(), the v_w and v_h parameters represent the
       minimum size of virtual screen that is acceptable for your program. The
       range of possible sizes is usually very restricted, and Allegro may end
       up creating a virtual screen much larger than the one you request.
       Allowed sizes are driver dependent and some drivers do not allow
       virtual screens that are larger than the visible screen at all: don't
       assume that whatever you pass will always work.

       In mode-X the virtual width can be any multiple of eight greater than
       or equal to the physical screen width, and the virtual height will be
       set accordingly (the VGA has 256k of vram, so the virtual height will
       be 256*1024/virtual_width).

       Currently, using a big virtual screen for page flipping is considered
       bad practice.  There are platforms which don't support virtual screens
       bigger than the physical screen but can create different video pages to
       flip back and forth. This means that, if you want page flipping and
       aren't going to use hardware scrolling, you should call set_gfx_mode()
       with (0,0) as the virtual screen size and later create the different
       video pages with create_video_bitmap(). Otherwise your program will be
       limited to the platforms supporting hardware scrolling.

       After you select a graphics mode, the physical and virtual screen sizes
       can be checked with the macros SCREEN_W, SCREEN_H, VIRTUAL_W, and
       VIRTUAL_H.

RETURN VALUE
       Returns zero on success. On failure returns a negative number and
       stores a description of the problem in allegro_error.


SEE ALSO
       set_color_depth(3), request_refresh_rate(3), screen(3),
       gfx_capabilities(3), allegro_error(3), create_video_bitmap(3),
       get_desktop_resolution(3), SCREEN_W(3), SCREEN_H(3), VIRTUAL_W(3),
       VIRTUAL_H(3)



Allegro                          version 4.2.3                 set_gfx_mode(3)
