mvGrabRelease(3dm)					    mvGrabRelease(3dm)

NAME    [Toc]    [Back]

     mvGrabOpenGL, mvReleaseOpenGL - provide safe usage	of graphics libraries
     from Movie	Playback Library clients

SYNOPSIS    [Toc]    [Back]

     #include <dmedia/movieplay.h>


     void mvGrabOpenGL(void);

     void mvReleaseOpenGL(void);

DESCRIPTION    [Toc]    [Back]

     mvGrabOpenGL(3dm) tells the Movie Playback	Library	that your application
     wishes to use OpenGL.  These functions temporarily	suspend	display	of all
     movie instances until you call mvReleaseOpenGL(3dm).  mvGrabOpenGL(3dm)
     does not stop playback; instead, it merely	suspends the display of	images
     on	the workstation	screen.

     Internally, the Movie Playback Library uses the sproc(2) system call to
     provide asynchronous playback in a	separate execution thread. Multiple
     threads in	the same process may have access to the	graphics library, but
     no	two threads may	issue a	graphics library call simultaneously.  Thus,
     you must tell Movie Playback Library when you intend to use the graphics
     library so	that it	can avoid making a graphics library call at the	same
     time you do.  Currently under X11,	in order to have multiple threads work
     safely, each thread must have it's	own display connection.	 The Movie
     Playback Library opens up a separate display connection for each thread
     that needs	one and	it uses	the display connection provided	via
     mvOpenPort(3dm) or	mvBindOpenGLWindow(3dm)	in the thread in which those
     calls were	invoked.

     If	you perform graphics library rendering in the same process as you use
     the Movie Playback	Library	for playback, you should call the relevant
     grab function before and release function after those places in your code
     where graphics library calls are invoked.	The Movie Playback Library
     will not update the on-screen images of the movies	while you have grabbed
     the graphics library, so if your rendering	takes a	long time, movie
     playback will appear interrupted.

     Once you grab the graphics	library, you must always call
     mvReleaseOpenGL(3dm) to resume normal movie playback.  You	must not call
     mvReleaseOpenGLmvSetEnableVideo(3dm).  Then, you request frame events via	the Movie
     Playback Library event queue.  When you receive a frame event, you	can



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mvGrabRelease(3dm)					    mvGrabRelease(3dm)



     tell Movie	Playback Library to display the	frame by calling
     mvShowCurrentFrame(3dm).  This alternate method will eliminate any	chance
     of	contention for the graphics library, without requiring you to use
     mvGrabOpenGL(3dm).

SEE ALSO    [Toc]    [Back]

     mvBindOpenGLWindow(3dm), mvIntro(3dm), mvNextEvent(3dm), mvOpenPort(3dm),
     mvRenderMovieToImageBuffer(3dm), mvRenderMovieToOpenGL(3dm),
     mvSetEnableVideo(3dm), sproc(2)


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