glutOverlayDisplayFunc(3GLUT)					       GLUT					     glutOverlayDisplayFunc(3GLUT)

NAME

       glutOverlayDisplayFunc - sets the overlay display callback for the current window.

SYNTAX

       void glutOverlayDisplayFunc(void (*func)(void));

ARGUMENTS

       func	 The new overlay display callback function.

DESCRIPTION

       glutDisplayFunc sets the overlay display callback for the current window. The overlay display callback is functionally the same as the win-
       dow's display callback except that the overlay display callback is used to redisplay the window's overlay.

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

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

       Upon return from the overlay display callback, the overlay damaged state of the window (returned by calling  glutLayerGet(GLUT_OVERLAY_DAM-
       AGED) is cleared.

       The  overlay display callback can be deregistered by passing NULL to glutOverlayDisplayFunc. The overlay display callback is initially NULL
       when an overlay is established. See glutDisplayFunc to understand how the display callback alone is used if an overlay display callback	is
       not registered.

SEE ALSO

       glutDisplayFunc, glutPostOverlayRedisplay

AUTHOR

       Mark J. Kilgard (mjk@nvidia.com)

GLUT
									3.7					     glutOverlayDisplayFunc(3GLUT)