Tim Crane (wen1/stereo++at++wenet.net)
Fri, 18 Sep 1998 09:59:57 -0700
The newer quad buffered format the images are
drawn full screen. There is two
Left eye buffers and two Right eye buffers.
While one image is displayed the
other is being drawn in the non displayed
buffer. The left and right buffers
get sent to the monitor at 60 Hz each eye for
a total of 120 Hz. When the
computer is in the quad buffered mode, the
monitor runs at 120 Hz. The emitter
still receives the same 60 Hz square wave to
synchronize the eyeware.
The advantage of this format is that since
the images are full screen, they do
not have to be sized and placed in a specific
area as with the above/below
format. Stereo in a window is also
possible. All the non stereo images are
written so they appear with no parallax and
the stereo images have horizontal
parallax.
Two basic things happen for stereo. First
the computer is placed in a stereo
resolution, and second the stereo images are
displayed.
The stereo content must be written for the
specific format. If you attempt to
use above/below format in a quad buffered
system the images will not be sized
right and weird results will happen.
P J Narayanan wrote:
> Hi,
>
> 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
> --------
> Centre for Artificial Intelligence and Robotics +91 80 226 5609 (Phone)
> Raj Bhavan Circle, High Grounds +91 80 225 5615 (Fax)
> Bangalore 560 001, INDIA
> URL: http://www.cair.res.in/~pjn pjn++at++cair.res.in
> =======================================================================
> List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/
> Submissions: info-performer++at++sgi.com
> Admin. requests: info-performer-request++at++sgi.com
-- Please feel free to contact me if you have any questions.Tim Crane, Quality Mgr. StereoGraphics Tech Support 2171 E. Francisco Blvd. San Rafael CA 94901 415-459-4500 415-455-1844 fax internet: tcrane++at++crystaleye.com Web: http://www.stereographics.com *** This letter printed on 100% recyclable phosphor. ***
This archive was generated by hypermail 2.0b2 on Fri Sep 18 1998 - 19:05:33 PDT