TRIGGER-STEREO 

Chuck Sites Oct 2004
chuck@cvip.uofl.edu

[Edited by Jon Langridge]


INTRODUCTION

   Trigger is an aswome game visually speeking and when I first saw it
I wanted to get some stereo hooks into it to really explore the maps
and scenes in 3D (Vitual Reality) like stereo graphics.  These stereo
patches work nice.  I've been working with stereo vision for a long
time starting with SGI workstations for about 10Years I've longed for
that capability with linux.  Well I think it has finally arrived in
hardware with the Nvidia line of Quadro cards and the ATI FireGL
cards.  The cards work, and work probably better than the SGI
workstations series.  The Down side is the an entry level QuadroFX/500
card (about the equivilent of a GeForceFX 5200) cost about $300!
compared to $49 for the GeForce.  Anyway, I wanted to put together
some tips on how to get the best quad-buffer stereo preformance with
linux.

SUPPORTED CARDS:

Nvidia Quadro series
ATI FireGL series  
Hardware hacked GeForce2 cards.  See: 

'http://www.geocities.com/tnaw_xtennis/G-Quadro-2.htm'

I've done this to a couple of cards and it really is not easy, and 
I've lost some cards overtime so I can't say the hardware fix is 
really stable. Some cards are not hackable.  

Read the NVIDIA-linux driver release notes on how to configure
your /etc/X11/XF86Config-4 file to support stereo with the 
option "stereo".  I've not had experience with ATI's linux 
drivers but I've heard it isn't pleasant. 

LCD SHUTTER GLASSES

If you have a supported card, you need the a pair of lcd shutter
glasses and a Sync Doubler, see: 'http://www.stereo3d.com/control.htm'
I-glasses makes one of the nicest consumer level glasses, that
includes all the hardware needed for Quad-Buffer stereo.  They are at:

'http://www.i-glassesstore.com/'

The EXtreme 3D Game Glasses is pretty nice $69 for the wired, $89 
wireless. 

'http://www.3dmedialabs.com/3dml-002.html'

 

SUPPORTED CRT's. 

 If you have an LCD monitor, I'm sorry to say
there is no hope doing stereo without going to some sort of polorizer
systems (see: 'http://www.soft.lt/hardware/lcd/' for an interesting 
discussion).   

 The monitor is important and you will probably want a newer type 
digital monitor.  An old VGA monitor that support 800x600 just is
not going to work well.  You really need a CRT that will support 
high vertical refresh rate (75 - 85Hz) .  The speed
between toggling from a left eye view to a right eye view is
determined by the vertical sync rate.  A monitor that supports
1280x1024 @ 60Hz will have a noticable flicker give about 30/Fps per
Eye.  Many newer digital monitors will do 640x480 @ 85Hz (about 42
FPS/Eye) and has noticably less flicker.  On my monitor (An el-cheapo
Cybervision Dx/86 17") monitor supports 768x586 @ 100Hz which is very
easy on the eyes.

You can toggle between the modes using X-Windows <CTRL><ALT><KEYPAD +> 
and <CTRL><ALT><KEYPAD -> or configure a default resolution in you 
/etc/X11/XF86Config-4 file. 

I've found a really nice utility in the 'StereoGL' project on
SourceForge called 'vmode'.  'http://stereogl.sourceforge.net/' 
On digital monitors, vmode will report all of the video-mode 
combinations your monitor supports.  It's included in the directory.


TRIGGER STEREO SUPPORT.

Stereo is configured with the trigger.config file under the
video settings.   

stereo="none"
    or "quadbuffer"
    or "red-blue"
    or "red-green"
    or "red-cyan"
    or "yellow-blue"
    - Enables stereo and selects a mode.

stereoeyeseperation="0.07"
    - Changes the images based on how far apart your eyes are.
      The value is the distance between your eyes in metres.
      Decrease this value if you feel uncomfortable or for
      children, but avoid increasing it too much.

stereoswapeyes="no" or "yes"
    - Set this to "yes" if the image appears to be swapped.


Have Fun.
Chuck Sites



[ PERFORMANCE NOTES

Out of the five stereo modes available, quad buffer (with appropriate
hardware) is likely to be the most efficient, and will definitely
give the best visual effect. However, many people will probably only
be able to use the anaglyph stereo modes (red-blue, etc).

It's worth noting that red-cyan and yellow-blue modes will have
the best performance. If you have red-blue or red-green glasses,
I suggest trying the red-cyan display mode first, since you will
get better framerates in the game. If this produces "ghosting"
effects, then try the red-blue or red-green modes as appropriate.

Many thanks to Chuck for a great Trigger add-on!

- Jon ]
