Grump about Compiz + GL + blinking

11 01 2009

Being home sick makes me turn my attention to gaming. I’ve gotten back into Puzzle Pirates, and that’s been good for multiplayer, general quiet entertainment. I’ve backed off on Eve Online, for a number of reasons (not being home / in front of a windows game machine all the time is pretty key).

Last night I decided to do a little more involved gaming on ‘algol’, my linux laptop. HappyPenguin provided a couple interesting options, a few showing up in apt, so I installed one.

The problem is, the app I chose (SuperTuxKart), blinks like crazy when running. I’d seen this behaviour in the Compiz / Xscreensaver screens, but thought it was something specific to XScreenSaver’s interraction with Compiz. Alas, that’s not the case.

This is a known problem with Ubuntu installations that use Compiz as their default compositing window manager. According to this page on the Ubuntu wiki…

Summary
Currently opengl apps do not work correctly when composite is running. This is a BIG bug and annoyance for desktop users, especially as composite-by-default is set to be included for gutsy. This should be fixed via redirected direct rendering. It is especially important as modern applications use opengl interfaces, such as blender and google earth, but also for smaller opengl parts, such as the visualisations in amarok.

Rationale
Users of ubuntu, both advanced users and novices, find it annoying to have to disable the compositioning window manager whenever they want to run an opengl accelerated application. Solving this requires deep changes to the structure of the X server and the display drivers, and is a future plan for the Xorg devs: http://dri.freedesktop.org/wiki/DirectRenderingToRedirectedWindows (A prototype for this has been developed by Kristian Hogsberg: http://hoegsberg.blogspot.com/2007/08/redirected-direct-rendering.html). However, it is a big job, so I believe that the Ubuntu devs should help out.

So, if you use Ubuntu and GL apps and Compiz, and you have the blinks, there’s no known fix. I’m guessing it’s specific to certain video drivers, because I know some systems work fine, but on this machine (which uses an Intel 945GM chipset), looks like it’s no GL for me.

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One response

11 01 2009
orion

that problem also exists in non-Ubuntu distributions, but AFAIK only with ATI’s drivers. my machine at school, which runs Ubuntu but has an nVidia card, doesn’t exhibit that behavior — OpenGL apps run just fine even with Compiz / compositing turned on. but ATI’s drivers suck for Linux, and my laptop (which has an ATI) car exhibits the problem you describe above. bleh.

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