Angus Dorbie (dorbie++at++sgi.com)
Fri, 18 Sep 1998 18:06:01 -0700
Old style used to take a single frontbuffer and send the top
and bottom half as left and right eyes. The application drew
left and right to top and bottom halves of the screen leaving
some space for blanking.
New stereo uses quad buffering. It sends the desktop to each
eye every frame, if you have a stereo visual in a window then
that portion of the framebuffer has a left and right eye
buffer not just a single front buffer. Each eye gets a separate
image from the stereo buffer.
For your application this means that instead of rendering to
top and bottom windows you render to left and right eye
buffers then swap, you must also request a stereo framebuffer
visual format to support the buffering. You actually have 4
buffers left & right * back & front.
Cheers,Angus.
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
-- "Only the mediocre are always at their best." -- Jean GiraudouxFor advanced 3D graphics Performer + OpenGL based examples and tutors: http://www.dorbie.com/
This archive was generated by hypermail 2.0b2 on Fri Sep 18 1998 - 18:06:05 PDT