glutDisplayFunc(3GLUT)						       GLUT						    glutDisplayFunc(3GLUT)

NAME

       glutDisplayFunc - sets the display callback for the current window.

SYNTAX

       void glutDisplayFunc(void (*func)(void));

ARGUMENTS

       func	 The new display callback function.

DESCRIPTION

       glutDisplayFunc	sets  the  display callback for the current window.  When GLUT determines that the normal plane for the window needs to be
       redisplayed, the display callback for the window is called. Before the callback, the current window is set to  the  window  needing  to	be
       redisplayed  and (if no overlay display callback is registered) the layer in use is set to the normal plane. The display callback is called
       with no parameters. The entire normal plane region should be redisplayed in response to the callback (this includes  ancillary  buffers	if
       your program depends on their state).

       GLUT  determines  when the display callback should be triggered based on the window's redisplay state. The redisplay state for a window can
       be either set explicitly by calling glutPostRedisplay or implicitly as the result of window damage reported by the window system.  Multiple
       posted redisplays for a window are coalesced by GLUT to minimize the number of display callbacks called.

       When  an  overlay is established for a window, but there is no overlay display callback registered, the display callback is used for redis-
       playing both the overlay and normal plane (that is, it will be called if either the redisplay state or overlay redisplay state is set).	In
       this case, the layer in use is not implicitly changed on entry to the display callback.

       See glutOverlayDisplayFunc to understand how distinct callbacks for the overlay and normal plane of a window may be established.

       When  a window is created, no display callback exists for the window. It is the responsibility of the programmer to install a display call-
       back for the window before the window is shown. A display callback must be registered for any window that is shown.  If	a  window  becomes
       displayed  without  a  display  callback being registered, a fatal error occurs. Passing NULL to glutDisplayFunc is illegal as of GLUT 3.0;
       there is no way to ``deregister'' a display callback (though another callback routine can always be registered).

       Upon return from the display callback, the normal damaged state of the window (returned	by  calling  glutLayerGet(GLUT_NORMAL_DAMAGED)	is
       cleared.  If  there  is	no  overlay  display  callback	registered the overlay damaged state of the window (returned by calling glutLayer-
       Get(GLUT_OVERLAY_DAMAGED) is also cleared.

SEE ALSO

       glutCreateMenu, glutPostRedisplay, glutOverlayDisplayFunc

AUTHOR

       Mark J. Kilgard (mjk@nvidia.com)

GLUT
									3.7						    glutDisplayFunc(3GLUT)