mount_overlay(8) [netbsd man page]

MOUNT_OVERLAY(8)					    BSD System Manager's Manual 					  MOUNT_OVERLAY(8)

NAME

     mount_overlay -- mount an overlay filesystem; demonstrate the use of an overlay file system layer

SYNOPSIS

     mount_overlay [-o options] /overlay mount-point

DESCRIPTION

     The mount_overlay command creates an overlay layer, interposing the overlay filesystem between the over-mounted file store and future path-
     name lookups.

     A different device number for the virtual copy is returned by stat(2), but in other respects it is indistinguishable from the original.

     The mount_overlay filesystem differs from the null filesystem in that the mount_overlay filesystem does not replicate the sub-tree, it places
     itself between the sub-tree and all future access.

     The overlay layer has two purposes.  First, it serves as a demonstration of layering by providing a layer which does nothing other than
     insert itself over the over-mounted file system.  Second, the overlay layer can serve as a prototype layer.  Since it provides all necessary
     layer framework, new file system layers which need to block access to the overlayed file system can be created very easily by starting with
     an overlay layer.

     The internal operation of the overlay layer is identical to that of the null layer.  See its documentation for details.

SEE ALSO

     mount(8), mount_null(8)

     UCLA Technical Report CSD-910056, Stackable Layers: an Architecture for File System Development.

HISTORY

     The mount_overlay utility first appeared in NetBSD 1.5.

BSD
								 January 18, 2000							       BSD

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)