[osg-users] Fwd: Unstable passive stereo on Quadro using Quadbuffer

Voerman, L. l.voerman at rug.nl
Tue Nov 15 07:17:01 PST 2016

Hi TianZJ,
we have a zSpace screen (closely related to your HP screen), and found that
to get stereo working the screen needs a usb cable and the following calls
to the zSpace SDK must be made:

ZSError error;
// Initialize the zSpace SDK. This MUST be called before
// calling any other zSpace API.
error = zsInitialize(&_zSpaceContext);
if (error != ZS_ERROR_OKAY) {
char errorString[256];
zsGetErrorString(error, errorString, sizeof(errorString));
// MessageBox(NULL, errorString, "ZSError", MB_OK | MB_SETFOREGROUND |
_zSpaceContext = NULL;
ZSHandle    g_bufferHandle = NULL;
error = zsCreateStereoBuffer(_zSpaceContext, ZS_RENDERER_QUAD_BUFFER_GL, 0,
if (g_bufferHandle) {
//I do this at program shutdown, but suspect this can be done at once if
you're not useing the headtracking/pen tracking.
// Shutdown and cleanup the zSpace SDK.
_zSpaceContext = NULL;

I don't know if HP has created it's own SDK or refers you directly to
zSpace for the software, but I think you need a similar sequence.
btw. The signal is send as frame sequential stereo - commonly referred to
as "active stereo signal" trough a single video cable.
Referring to this system as passive stereo just because the glasses are
passive confuses a lot of people. (the display switches circular
polarization at 120 Hz)

Regards, Laurens.

On Tue, Nov 15, 2016 at 2:24 PM, Jan Ciger <jan.ciger at gmail.com> wrote:

> On Tue, Nov 15, 2016 at 11:45 AM, ZJ Tian <tianzjyh at gmail.com> wrote:
>> Hi, Jan,
>> You lightened my way. That's the answer I think.
>> I will try to work it out though you guessed correctly the display device
>> I am unluckily using.
> You are welcome.
> Sadly, these problems are common. The hardware vendors will claim that
> their gizmo is perfect, does everything out of the box and, of course, plug
> and play. Only when you actually buy it you will discover that the sales
> materials neglected to mention that the function you need requires a very
> expensive accessory sold extra and made out of unobtanium (because nobody
> stocks it - like the mini-DIN connector brackets for Quadros) or that the
> function actually works, but it is severely limited to the point of being
> unusable because some fool somewhere decided to save $0.1 by eliminating a
> connector or shipping non-working firmware ...
> I have had these experiences even on very expensive pieces of hardware.
> Especially with VR you do have to always test before buying because the
> sales brochures and salesmen are never telling the whole story if not lying
> outright.
> J.
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