glutEnterGameMode,  glutLeaveGameMode  - enters and leaves
       GLUT's game mode.

SYNTAX

       void glutEnterGameMode(void);
       void glutLeaveGameMode(void);

DESCRIPTION

       glutEnterGameMode is designed to  enable  high-performance
       fullscreen  GLUT rendering, possibly at a different screen
       display format.  Calling glutEnterGameMode creates a  spe-
       cial  fullscreen  GLUT  window (with its own callbacks and
       OpenGL rendering context state).  If the game mode  string
       describes  a  possible  screen  display  format, GLUT also
       changes the screen display format to the one described  by
       the  game  mode string.  glutLeaveGameMode leaves the GLUT
       game mode and returns the screen  display  format  to  its
       default format.

       When  game  mode is entered, certain GLUT functionality is
       disable to facilitate high-performance fullscreen  render-
       ing.   GLUT  pop-up  menus are not available while in game
       mode.  Other created windows and subwindows are  not  dis-
       played  in  GLUT  game mode.  Game mode will also hide all
       other  applications  running  on  the  computer's  display
       screen.   The intent of these restrictions is to eliminate
       window  clipping  issues,  permit  screen  display  format
       changes, and permit fullscreen rendering optimization such
       as page flipping for fullscreen buffer swaps.

       After leaving game mode, the GLUT  functionality  disabled
       in  game  mode  is  available again.  The game mode window
       (and its OpenGL rendering state) is destroyed when leaving
       game  mode.   Any  windows  and  subwindows created before
       entering the game mode are  displayed  in  their  previous
       locations.   The  OpenGL  state of normal GLUT windows and
       subwindows is not disturbed  by  entering  and/or  leaving
       game mode.

       The  following  GLUT  routines  are  ignored in game mode:
       glutFullScreen,   glutSetWindowTitle,    glutSetIconTitle,
       glutPositionWindow,    glutReshapeWindow,   glutPopWindow,
       glutPushWindow,     glutIconifyWindow,     glutShowWindow,
       glutHideWindow.

       glutEnterGameMode can be called when already in game mode.
       This will destroy the previous game mode window (including
       any  OpenGL  rendering  state)  and create a new game mode
       window with a new OpenGL rendering context.  Also if  glu-
       tEnterGameMode  is called when already in game mode and if
       the game mode string has changed and describes a  possible
       screen display format, the new screen display format takes

       Re-entering game mode provides a  mechanism  for  changing
       the  screen  display  format  while  already in game mode.
       Note though that the game mode window's  OpenGL  state  is
       lost  in  this  process and the application is responsible
       for re-initializing the newly  created  game  mode  window
       OpenGL state when re-entering game mode.

       Game mode cannot be entered while pop-up menus are in use.

       Note that the glutEnterGameMode  and  glutFullScreen  rou-
       tines  operate  differently.   glutFullScreen simply makes
       the current window match the size of  the  screen.   glut-
       FullScreen  does  not change the screen display format and
       does not disable any GLUT features such as  pop-up  menus;
       glutFullScreen  continues  to operate in a "windowed" mode
       of operation.   glutEnterGameMode  creates  a  new  window
       style,  possibly  changes  the screen display mode, limits
       GLUT functionality, and hides other applications.

SEE ALSO

       glutGameModeGet, glutGameModeString, glutInitDisplayString

AUTHOR

       Mark J. Kilgard (mjk@nvidia.com)