Re: Frame Buffer Attributes for Top-down stereo mode

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From: Tom Flynn (flynnt++at++engr.sgi.com)
Date: 02/22/2001 15:37:59


/usr/share/Performer/src/pguide/libpf/stereotb.c

hope that helps,
tom

On Thu, 22 Feb 2001, Matthew Hall wrote:

> G. Anthony Reina wrote:
> >
> > I've got a stereo program that I'm converting from a quad-buffered
> > stereo monitor to a older top-down stereo monitor.
> >
> ...
> > On the top-down stereo, the setmon command is /usr/gfx/setmon -n
> > STR_RECT which gives a 1280x1024 screen at 120 Hz.
> >
> > When I try just setting pfPWinFBConfigAttrs to:
> >
> > int FBAttrs[] = {
> > PFFB_STEREO,
> > None
> > };
> >
> > or any variation of the double buffer FB Config (without the
> > PFFB_DOUBLEBUFFER since the monitor can't do quad buffering), Performer
> > tells me that it can't execute the command properly.
>
> Using STR_RECT, or interlaced, stereo is less automatic. I haven't
> tried to use it with performer, but I've made interlaced stereo
> apps with pure OpenGL, so I can outline the general idea.
> (sorry for any OspenGL terminology - I'm a Performer neophyte)
>
> Interlaced stereo doesn't require any special buffer options
> (so don't use PFFB_STEREO, and do use PFFB_DOUBLEBUFFER).
> In fact, it doesn't interact with OpenGL at all. Instead,
> calling setmon STR_RECT maps the top half of the screen buffer into the
> even numbered raster lines, and the bottom half into the odd.
> Then it sets the monitor to interlace, starts up the shutter glasses,
> and draws the even lines to the left eye on one refresh, and odd to
> the right on the other. (I may have reversed even/odd, but the top
> does go to the left eye)
>
> So to use stereo in full screen mode,
> 1) send the setmon command,
> 2) Set the viewport to (0,0,1280,491) and draw the left eye's view.
> 3) Set the viewport to (0,532,1023) and draw the right eye's view.
> (read more in the manpage stereo(7))
>
> Note that the effective resolution is halved, and that pixels are no
> longer square. This is one reason why quad-buffered is much nicer.
>
> Sorry I can't tell you how to use performer to do this, but if
> you or someone else can use this information to make interlaced
> stereo work in Performer, let me know!
>
> -matt
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