How do I wait for vertical retrace?
johan.walles at gmail.com
Tue May 6 04:12:39 PDT 2008
2008/5/6 Samuel Thibault <samuel.thibault at ens-lyon.org>:
> Michel Dänzer, le Tue 06 May 2008 09:37:23 +0200, a écrit :
> > On Mon, 2008-05-05 at 15:43 +0100, Samuel Thibault wrote:
> > > Michel Dänzer, le Mon 05 May 2008 10:22:19 +0200, a écrit :
> > > > On Sun, 2008-05-04 at 20:06 +0200, Johan Walles wrote:
> > > > >
> > > > > I would like to wait for vertical retrace in an X application. How
> > > > > can I do that?
> > > > >
> > > > > The point would be to avoid flicker in my app by using double
> > > > > buffering and update the on-screen image during vertical retrace.
> > > >
> > > > There's no mechanism for this yet in X. Your best bet is probably to use
> > > > OpenGL, e.g. the GLX_SGI_swap_control extension.
> > >
> > > Isn't there a more simple double buffering X extension?
> > You mean DOUBLE-BUFFER?
> > I'm not really familiar with it, but I know that
> > at this time it can't synchronize buffer swaps to the refresh.
> Eww, that would be a pity. At the very beginning of the Extension
> documentation (Johan: xspecs/Xext/buffer.PS), it is said `Clients should
> be able to [...] Display a series of buffers in a window in rapid
> succession to achieve a /smooth/ animation', which is what Johan wants
> to eventually achieve AIUI (vertical retrace wait being only one method,
> I don't know whether which others could be possible).
Samuel, that sounds like *exactly* what I was after.
I don't care about vertical retrace in itself, waiting for vertical
retrace would only be a way for me to achieve flicker-free animation
in a 2D application. Any other way of doing that would be fine as
More information about the xorg