VMD-L Mailing List

From: Dr. Daniel James White PhD (dan_at_chalkie.org.uk)
Date: Fri Jun 13 2003 - 03:50:12 CDT

Hi John,

> - If the application draws both the left and right eyes to the same
> buffer,
> one of the two images will "win", i.e. the last image drawn will be
> rendered "on top" of the other one. This situation looks _very_
> different
> from what one sees if you look at a normally functioning stereo
> display without your LCD glasses. Typically, if the application
> is
> at fault, you will see "jagged intersections" between the geometry
> in
> the left eye image and the geometry in the right eye image.
> (assuming
> the Z-buffer was not cleared). If the Z-buffer was cleared, then
> the result is that the last image drawn (right eye) will look
> normal,
> but the parts of the first image drawn (left eye) will show up in
> places
> where they are not obscured by the last image, where one would have
> normally seen the background color.
> OpenGL does not provide a means for an app to show both left and
> right
> buffers at once. You can only show one or the other. The only
> way to
> see pieces of both left and right images is if you draw them both
> to the
> same buffer, but the artifacts make this easy to spot if it ever
> happens,
> it looks VERY different from what you'd see if you took off your
> stereo
> glasses and looked at a normally operating stereo display.
>

The left eye image is indeed drawn over/ontop of the right eye image!
clearly seen when viewing a molecule in licorice or ribbons!

so a VMD bug then?

I haven't done the
VMDPREFFERSTTEREO thing yet.... I have to set this as an environment
variable as on right?

> - If the problem is caused by the video driver or the emitter box
> hardware,
> or some combination thereof, you may see the left, right, neither,
> or both
> images in each eye, sync may be lost and regained intermittently,
> or
> combinations of these problems. This type of problem is
> distinguishable
> from bugs in the application because it isn't possible for the
> application
> to request "both" the left and right color buffers to be shown
> simultaneously, so if you see both the left and right images
> simultaneously and they look just like they do if you take the
> glasses off, this would indicate a driver or hardware problem of
> some kind. Other problems like "tearing" flickering GUI windows
> or strange colors in GUI windows in one eye but not the other, are
> also
> all problems that occur result from the video driver and hardware.

my mouse pointer seems to cause artifacts sometimes, so that must be a
driver problem as it occurs with all (stereo?)applications

cheers

Dan

Dr. Daniel James White BSc. (Hons.) PhD
Cell Biology
Department of biological and environmental science
PO Box 35
University of Jyväskylä
Jyväskylä FIN 40014
Finland
+358 (0)14 260 4183 (work)
+358 (0)414740463 (mob)

http://www.chalkie.org.uk
dan_at_chalkie.org.uk
white_at_cc.jyu.fi