How do I wait for vertical retrace?

Chuck Robey chuckr at
Tue May 6 10:07:42 PDT 2008

Hash: SHA1

Carsten Haitzler (The Rasterman) wrote:
> On Tue, 06 May 2008 12:46:06 -0400 Chuck Robey <chuckr at> babbled:
> Nicolas George wrote:
>>>> L'octidi 18 floréal, an CCXVI, Johan Walles a écrit :
>>>>> 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.
>>>> DOUBLE-BUFFER is no good for that: when used for continuous animation (such
>>>> as video), it causes exactly as much tearing as a simple bitmap copy. At
>>>> least it was true in November 2006.
> That seems odd.  I'm currently reading the OpenGL Redbook (their latest
> programming manual) and it seems to be directly contradicting you.  I haven't
> tried it yet myself, though, but still, are you sure about that statement?
> What they say does seem to make sense.
>> opengl is not related to the x doulebuffer extension... :)

OK, sorry, I'd guessed they were one and the same technical item (if perhaps
done through separate code).  The OpenGL book told that it was a good method to
avoid flickering, so it seemed to me to be apropos, but I'm wrong then, sorry.
As I said, I'd mistatenly equated flickering to tearing, didn't realize you
could have tearing with only a single video source.  Sorry, let this die please.

>>>> Regards,
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