Bug 760 - severe flickering with rendering on root window
Summary: severe flickering with rendering on root window
Alias: None
Product: DRI
Classification: Unclassified
Component: General (show other bugs)
Version: DRI git
Hardware: x86 (IA32) Linux (All)
: high normal
Assignee: Default DRI bug account
QA Contact:
Depends on:
Reported: 2004-06-16 22:17 UTC by D Brooks
Modified: 2009-06-30 07:05 UTC (History)
2 users (show)

See Also:
i915 platform:
i915 features:


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Description D Brooks 2004-06-16 22:17:18 UTC
Attempting to run a DRI accelerated rendering with the radeon and rv200 drivers,
on the root window, leads to severe flickering. [Perhaps double buffering is not
active? But this flickering seems to be somewhat Z-dependent... Within the
flickering, you can sometimes see things being drawn that should be occluded by
other objects]].

To replicate the problem:
Use, say, one of the gl xscreensavers, [located in /usr/X11R6/lib/xscreensavers
on my distribution]

such as:
./superquadrics -root

And the problem will be quite apparant. 
This only happens when openGL applications are run on the root window. 

Comment 1 James Renken 2004-06-17 12:32:26 UTC
Duplicated with ATI All-in-Wonder (Radeon) 9000 AGP 64MB and glmatrix.
Comment 2 Adam Jackson 2004-06-17 12:59:56 UTC
~$ /usr/lib/xscreensaver/glmatrix -visual 39 -root
glmatrix: ignoring `-visual 39' because of `-root'.
glmatrix: using root window's visual 0x23.

0x23 is not double-buffered.
Comment 3 D Brooks 2004-07-23 01:34:51 UTC
How can one change the visual id of the root window, then? This isn't a problem
with my nvidia card. I have tried running X with all -cc options between 0x00
and 0x50, and it refuses to run in each case!
Comment 4 Ian Romanick 2004-07-26 08:35:20 UTC
AFAIK, you can't.  If the root window doesn't have the required capabilities,
don't use it.  It's just that easy.
Comment 5 Adam Jackson 2004-07-26 09:26:07 UTC
i asked keithp about this a while ago.  it's not impossible to do, but it
involves hacking the server to enable a back buffer for the root window.
Comment 6 Dieter Nützel 2004-10-21 11:17:09 UTC
This is a 'problem' with all xscrennsaver GL modules in KDE 3.3.1 at least. 
They request for root and get unbuffered. 
/opt/Mesa> /usr/X11R6/lib/xscreensaver/queens -visual 39 -root 
queens: ignoring `-visual 39' because of `-root'. 
queens: using root window's visual 0x23. 
=> Nothing or flickering. 
But KDE's GL saver (keuphoria.kss) are working right. 
But we have more regression, here. 
flipscreen3d (big textures are broken, again): 
/opt/Mesa> /usr/X11R6/lib/xscreensaver/flipscreen3d -geometry 1280x1024 
flipscreen3d: error mipmapping 2048x1024 texture: (unknown) 
flipscreen3d: turning on -wireframe. 
=> Empty black flipping window. 
But this one works: 
/usr/X11R6/lib/xscreensaver/flipscreen3d -geometry 1024x1024 
/opt/Mesa> /usr/X11R6/lib/xscreensaver/flipscreen3d -geometry 1024x1025 
/opt/Mesa> /usr/X11R6/lib/xscreensaver/flipscreen3d -geometry 1024x1280 
/opt/Mesa> /usr/X11R6/lib/xscreensaver/flipscreen3d -geometry 1024x160 
/opt/Mesa> /usr/X11R6/lib/xscreensaver/flipscreen3d -geometry 1024x1600 
Badness starts here: 
/opt/Mesa> /usr/X11R6/lib/xscreensaver/flipscreen3d -geometry 1025x1024 
flipscreen3d: error mipmapping 2048x1024 texture: (unknown) 
flipscreen3d: turning on -wireframe. 
Comment 7 Ian Romanick 2004-10-21 13:03:42 UTC
As has been said 6.02E23 times before, this is a bug in xscreensaver.  The root
window isn't double buffered.  Get over it.
Comment 8 Adam Jackson 2008-02-24 18:23:47 UTC
Mass reopen.  The "REMIND" resolution is lame, I'm deleting it.  Consider yourself reminded.
Comment 9 Jerome Glisse 2009-06-30 07:05:50 UTC
This was an xscreensaver bug.

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