[Chimera-users] Slow framerates (on a nice laptop)

[Greg Couch]

On Fri, 13 Jan 2006, Charlie Moad wrote:

>     So in general I get really good performance with chimera, but for
> some reason I get really bad frame rates with more recent releases on
> windows with my laptop.  It has a really nice card, GeForce 6200TC Go.
> It is even on a pcix16 bus.  I am guessing that since it is a newer
> chipset, chimera is using shaders of some kind?  The molecule looks
> visually smoother/better than when in linux.  In any case, it seems
> something is getting enabled that really bogs it down, and I would
> like to be able to disable it.
>
> Sony Vaio FS500
> Chimera 1.2184

Sounds like, on Windows, chimera detects that your graphics card supports 
multisampling, ie., more than one sample per pixel, and is using it. 
Multisampling is used to reduce the staircase effect visible on polygon 
edges (ribbons, spheres, sticks, surfaces).

You can turn it off by giving the --nomultisample option when you start 
chimera (edit the chimera shortcut's properties and add --nomultisample to 
the Target field).

There are usually several levels of multisampling supported by the 
graphics card with tradeoffs between visual quality and performance. 
Chimera doesn't let you choose (yet), but the graphics driver lets you 
pick a particular one.  Change the "Antialiasing settings" from 
Application-controlled to particular value (Off, 2x, 4x, 8xS, or 16x on my 
Quadro -- probably a subset on the GeForce).

And the fact that you're not getting the same visual quality on Linux is a 
bug.  Chimera is supposed to behave the same across all platforms.

 	Greg Couch
 	UCSF Computer Graphics Lab
 	gregc at cgl.ucsf.edu