[Chimera-users] how to tell chimera to use the local python installation

Greg Couch gregc at cgl.ucsf.edu
Thu Jun 15 16:40:03 PDT 2006

On Thu, 15 Jun 2006, Sabuj Pattanayek wrote:

> Hi,
> With the release of xorg-7.1.1 and mesa-6.5 I finally have direct
> rendering for my i855gm/i810 intel video device under linux. However I
> get lots of flickering of an object inside of the chimera display window
> when I rotate or move the object.
> I don't have this issue with pymol (compiled against the system python)
> and vmd (compiled against C/C++ opengl bindings?) or even glxgears.
> Perhaps I can workaround this problem by telling Chimera to use the
> local python installation? How is this done?

The current version of chimera uses a modified Python, so it is not 
possible to substitute in a different one.  And even if you could, it 
shouldn't make any difference.  The difference is hidden somewhere in the 
graphics code.

The flickering is caused by not updating the contents of the graphics 
window during the display's vertical retrace.  This used to be on by 
default, but I guess that is no longer the case.  Maybe Mesa has 
environment variable like NVidia's __GL_SYNC_TO_VBLANK, which sets the 

There are also OpenGL extensions, MESA_swap_control and 
GLX_SGI_swap_control, that control the effect you're seeing.  If one of 
those extensions is supported by your setup, you should see it listed in 
the output of the glxinfo command.  Unfortunately, chimera doesn't use 
them yet.  Please use the "Report a Bug" dialog available via the Help 
menu and send me the output of the glxinfo command, so I have a bug to log 
the fix against.

 	Greg Couch
 	UCSF Computer Graphics Lab

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