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Bug 583 - SDL_flip doesn't wait for vertical retrace
Summary: SDL_flip doesn't wait for vertical retrace
Status: RESOLVED DUPLICATE of bug 406
Alias: None
Product: SDL
Classification: Unclassified
Component: video (show other bugs)
Version: 1.2.13
Hardware: x86 Linux
: P2 normal
Assignee: Ryan C. Gordon
QA Contact: Sam Lantinga
URL:
Keywords: target-1.2.14
Depends on:
Blocks:
 
Reported: 2008-05-04 03:07 UTC by Johan Walles
Modified: 2009-09-14 10:44 UTC (History)
1 user (show)

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Description Johan Walles 2008-05-04 03:07:21 UTC 
I have set up a screen with SDL_DOUBLEBUF.  Since double buffering isn't supported on my hardware for some reason (X11?), my SDL_DOUBLEBUF was ignored.  So far, so good.

However, when I do SDL_flip(), what happens is:
* SDL_UpdateRect(screen, 0, 0, 0, 0)

What I expected was:
* Wait for vertical retrace
* SDL_UpdateRect(screen, 0, 0, 0, 0)

Would it be possible for SDL_flip() to wait for vertical retrace before updating the actual on-screen display, even if the hardware doesn't support double buffering?
Comment 1 Johan Walles 2008-05-06 04:25:42 UTC 
I asked about this on the Xorg mailing list.

Doug Larrick suggests using DRM's drm_wait_vblank ioctl, or OpenGL's GLX_SGI_video_sync extension:
http://lists.freedesktop.org/archives/xorg/2008-May/035103.html

Michel Dänzer mentions a DOUBLE-BUFFER extension:
http://lists.freedesktop.org/archives/xorg/2008-May/035118.html

The DOUBLE-BUFFER extension is described here:
http://www.xfree86.org/current/dbe.pdf
Comment 2 Johan Walles 2008-05-06 04:31:46 UTC 
... and I also got to know that "the standard technique for double buffering is to use a pixmap as the 'back buffer'":
http://lists.freedesktop.org/archives/xorg/2008-May/035126.html
Comment 3 Ryan C. Gordon 2009-09-13 16:33:38 UTC 
Tagging this bug with "target-1.2.14" so we can try to resolve it for SDL 1.2.14.

Please note that we may choose to resolve it as WONTFIX. This tag is largely so we have a comprehensive wishlist of bugs to examine for 1.2.14 (and so we can close bugs that we'll never fix, rather than have them live forever in Bugzilla).

--ryan.
Comment 4 Patrice Mandin 2009-09-14 10:40:44 UTC 
Isn't this bug a duplicate for bug #406 ?
Comment 5 Patrice Mandin 2009-09-14 10:44:49 UTC 

*** This bug has been marked as a duplicate of bug 406 ***