P J Narayanan (pjn++at++cair.res.in)
Fri, 18 Sep 1998 12:27:40 -0500 (Etc/GMT)
Though this is not a Performer question, I am emboldened to ask it here
by the past discussions on this topic on this list. I request the person
who has quoted an SGI video engineer in the past to get me the answers
for this question from such a competent person.
What is the difference between the New style stereo and the Old style
stereo? I was under the impression that stereo disply on SGI machines
draws left and right eye views as alternate frames at a fast rate.
For instance, 1280x492_120s format will draw the left eye view -- a full
1280x492 (actually 1280x512 with the blank portion) window -- once
and switch to the similarly sized right eye view etc with each eye drawn
for 1/120th of a second. The CrystalEyes emitter controls the LCDs on
the glasses in synchrony with this switching. In this (old-style stereo)
mode, the stereo window is accessed as a large 1280x1024 buffer from the
program, the top half of which is the right eye view and the bottom half
the left eye view. There is no need to configure the window explicitly
as a stereo quad buffer window (say by using setFBConfigAttrs) to use
this mode effectively.
I was able to make the above work. The same program/philosophy does not
seem to work with any of the "New style" stereo modes, such as the
1025x768_96s we have on our Onyx/RE2. When I set display to this mode
(using a setmon), the CrystalEyes emitter turns on, but both eyes see
the same thing at all times. I also tried the example stereo program
that sets PFFB_STEREO using a setFBConfigAttrs. This seems to draw left
and right eye views on top/bottom halves of the screen.
I think I understand the Old style stereo correctly. (Or do I?) Can
someone explain the proper use of the new style stereo to me? The difference
between them is obvious even when no stereo-enabled program is running.
The windows all become twice the height with top and bottom halves showing
at the same time when the mode is switched to one of the old style stereo
modes using setmon. The screen looks normal when switched to one of the
new style stereo modes, however.
Sorry to bother this group with this question. I would appreciate any
help in this regard. Is there standard publication from SGI or otherwise
that answers all my questions?
Thanks in advance!
PJN
--------
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URL: http://www.cair.res.in/~pjn pjn++at++cair.res.in
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