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

glutEnterGameMode
	glutEnterGameMode() -> None
glutLeaveGameMode
	glutLeaveGameMode() -> None

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

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.

The value returned by glutEnterGameMode is a unique  small
integer  identifier  for the fullscreen window.  The range
of allocated identifiers starts at one. This window  iden-
tifier can be used when calling glutSetWindow.

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
effect.   A reshape callback is generated if the game mode
window changes size due to a screen display format change.

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.

glutGameModeGet, glutGameModeString, glutInitDisplayString

Mark J. Kilgard (mjk@nvidia.com)