glutOverlayDisplayFunc(3GLUT) GLUT glutOverlayDisplayFunc(3GLUT)
NAME
glutOverlayDisplayFunc - sets the overlay display callback for the cur-
rent 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 win-
dow. 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 glutPos-
tOverlayRedisplay 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(3), glutPostOverlayRedisplay(3)
AUTHOR
Mark J. Kilgard (mjk@nvidia.com)
GLUT 3.7 glutOverlayDisplayFunc(3GLUT)
Mac OS X 10.6 - Generated Thu Sep 17 20:20:42 CDT 2009