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. [
Duplicated with ATI All-in-Wonder (Radeon) 9000 AGP 64MB and glmatrix.
~$ /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.
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!
AFAIK, you can't. If the root window doesn't have the required capabilities, don't use it. It's just that easy.
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.
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 /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.
As has been said 6.02E23 times before, this is a bug in xscreensaver. The root window isn't double buffered. Get over it.
Mass reopen. The "REMIND" resolution is lame, I'm deleting it. Consider yourself reminded.
This was an xscreensaver bug.
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