Crytek's 3D implementation only results in a 1.5% performance hit

I wish the article had more information, but I think the idea alone - that you can create the right eye view out of the left one - is very interesting.

Given that Crytek has been incredible inventive with "faking" otherwise costly graphic effects (e.g. http://en.wikipedia.org/wiki/Screen_Space_Ambient_Occlusion ), I believe their 3D implementation is good enough to at least fool the human eye.

Any idea how this could be achieved? Could the Z-Buffer used for this somehow?