glXWaitVideoSyncSGI(3G)	    OpenGL Reference - GLX     glXWaitVideoSyncSGI(3G)



NAME
     glXWaitVideoSyncSGI - wait	for vertical retrace


C SPECIFICATION
     int glXWaitVideoSyncSGI( int divisor,
			      int remainder,
			      unsigned int *count )


PARAMETERS
     divisor

     remainder	glXWaitVideoSyncSGI puts the calling process to	sleep until
		the value of the vertical retrace counter modulo divisor
		equals remainder.


     count	Pointer	to variable which receives the value of	the vertical
		retrace	counter	when the calling process wakes up.


DESCRIPTION
     glXWaitVideoSyncSGI is part of the	SGI_video_sync extension.  This
     extension provides	a way to synchronize with the video frame rate of a
     monitor (in the case of an	interlaced display, the	synchronization	is
     actually with the field rate).

     A vertical	retrace	precedes the display of	each video frame.  The kernel
     maintains a 32-bit	unsigned integer counter for each graphics pipe	in the
     system.  This counter is initialized via the /usr/gfx/gfxinit command,
     and incremented upon each vertical	retrace.  Since	all the	video output
     channels of a graphics pipe must be genlocked, one	counter	suffices for
     all the monitors driven by	a pipe.

     A process can query or sleep on the counter of the	graphics pipe
     associated	with its current OpenGL	rendering context, provided that the
     rendering context is direct.  (See	glXCreateContext.)

     glXWaitVideoSyncSGI puts the calling process to sleep until the vertical
     retrace counter modulo divisor equals remainder.  When this condition is
     met it places the value of	the vertical retrace counter in	the location
     referenced	by count and returns zero.

     If	the current context is not direct, glXWaitVideoSyncSGI returns
     GLX_BAD_CONTEXT_SGI.  If divisor is less than or equal to zero,
     glXWaitVideoSyncSGI returns GLX_BAD_VALUE_SGI.  If	remainder is less than
     zero, or greater than or equal to divisor,	glXWaitVideoSyncSGI returns
     GLX_BAD_VALUE_SGI.






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glXWaitVideoSyncSGI(3G)	    OpenGL Reference - GLX     glXWaitVideoSyncSGI(3G)



MACHINE	DEPENDENCIES
     glXWaitVideoSyncSGI is not	supported on Personal Iris or VGX and VGXT
     systems.


SEE ALSO
     glXGetVideoSyncSGI, glXCreateContext, glXQueryVersion, glGetString
















































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