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glutOverlayDisplayFunc(3GLUT)                       GLUT                       glutOverlayDisplayFunc(3GLUT)



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

SYNTAX
       #include <GLUT/glut.h>

       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 call-back callback
       back is functionally the same as the window's display callback except that the overlay display  call-back callback
       back is used to redisplay the window's overlay.

       When  GLUT determines that the overlay plane for the window needs to be redisplayed, the overlay dis-play display
       play 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  call-back callback
       back (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 over-lay overlay
       lay display callbacks called.

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

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

SEE ALSO
       glutDisplayFunc(3G), glutPostOverlayRedisplay(3G)


AUTHOR
       Mark J. Kilgard (mjk@nvidia.com)



GLUT                                                 3.7                       glutOverlayDisplayFunc(3GLUT)