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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	redis-
       played, the display callback for	the window is called. Before the call-
       back, 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 parame-
       ters.  The entire normal	plane region should be redisplayed in response
       to the callback (this includes ancillary	buffers	if  your  program  de-
       pends 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 callback
       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  rou-
       tine 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)

NAME | SYNTAX | ARGUMENTS | DESCRIPTION | SEE ALSO | AUTHOR

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