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Re: [Public WebGL] Stereoscopic monitors

Hi Won,

Could you please tell a little bit more on the reprojection technique that's used in games to recreate the depth perception from just one buffer?




The "Cars 2" and the "CryENGINE 3" talks both mention it, but they were targeting game consoles. To be clear, I wasn't suggesting to implement this using WebGL; in particular, accessing the depth buffer is a challenge. I was suggesting that it could be done in the browser as a post-process before the scene is composited.

And this is all speculation on my part; I don't actually work on Chrome GPU.

On Oct 14, 2011 5:28 PM, "Won Chun" <wonchun@google.com> wrote:
On Fri, Oct 14, 2011 at 11:59 AM, Shropshire, Andrew A <shropshire@att.com> wrote:
Ok thanks for the information.  Perhaps some non-stereoscopic 3D display
will come along in the future that will be cheap.  If I were designing the
3D apis, I would anticipate this and make the projection part of the
pipeline removable.

Modern games actually don't do the "render left/right" approach because they don't have the budget. They use a reprojection technique that takes a single depth/color image and makes left/right views off of that. In theory, WebGL could do that during compositing into HTML, although there is the sticking issue of how to deal with disocclusion (i.e. the parts of the scene visible from one eye but not the source render) that tends to be application-specific. And, there's the issue whether it is worth it. I've spent 5 years developing 3-D displays, and don't really see much progress yet; it's one of those things that is perpetually an "emerging technology."
Also it might be helpful to have more text handling
routines and font support like SVG, to facilitate drawing of text in 3D so
that mundane work like improving the look of buttons, scrollbars etc in
business applications could be improved.  Maybe this is what Windows 8 will

WebGL is in the OpenGL spirit of being fairly low-level and minimal. This is the kind of thing that you expect to see in a library written on top of WebGL. One popular library is three.js:


Andrew Shropshire

AT&T Government Solutions, Inc.

-----Original Message-----
From: Steve Baker [mailto:steve@sjbaker.org]
Sent: Friday, October 14, 2011 11:44 AM
To: Shropshire, Andrew A
Cc: 'public_webgl@khronos.org'
Subject: Re: [Public WebGL] Stereoscopic monitors

No, unless the browser had some kind of special support, WebGL will not
appear any different from normal 2D images.  I doubt such support is
likely anytime soon because it would imply massive changes to at least the
<canvas> subsystem - and likely throughout all of HTML.  Stereo monitors
just aren't popular enough to make the effort that this would entail
remotely worthwhile.

Technically: To use stereoscopic displays, you have to render the entire
scene twice, once from the left-eye perspective, and again from the right
eye.  These two images then have to be overlaid or combined or written
into two separate rendering buffers.  There is support for doing this kind
of thing in OpenGL via various quad-buffer extensions and such.  But none
of that is present in WebGL (AFAICT).  Even if the extensions were
available, the whole concept of how the compositing pipeline would work in
stereo is not considered at all.

Also, IMHO, stereoscopic monitors are a complete waste of money.  Except
in very niche applications, stereoscopic 3D is highly problematic.  Issues
of dynamic depth of focus mean that barring some pretty stunning
technological leaps, these technologies will always cause people to suffer
headaches and other nasty symptoms - just as they do in 3D televisions.
To avoid this, the 3D-ness of the scene and the positioning of the camera
and set/lighting design has to be carefully considered.  It's not just a
matter of displaying the material correctly.

Shropshire, Andrew A wrote:
> If I write WebGl and my website has WebGl content, will it appear in 3D on
> a
> stereoscopic monitor (3D monitor), if I purchase one?  Ie is stereoscopic
> monitor support a benefit of using WebGl?
> Andrew Shropshire
> AT&T Government Solutions, Inc.
> 703-506-5708
> shropshire@att.com

 -- Steve