11.8SupportingBothMonoscopicandStereoscopicVersions 173
ax ,
RxR y z
Nx N x e Ny Nz
.
This means that in the worst case, it takes
41 1multiplication addition maximum comparison
operations. For checking the back-facing triangle for both views, the efficiency
of this test is improved by around 33 percent.
11.8SupportingBothMonoscopicand
StereoscopicVersions
If a game supports both stereoscopic and monoscopic rendering, the stereoscopic
version may have to reduce the scene complexity by having more aggressive lev-
el of detail (geometry, assets, shaders) and possibly some small objects or post-
processing effects disabled. Thankfully, the human visual system does not only
use the differences between what it sees in each eye to judge depth, it also uses
the similarities to improve the resolution. In other words, reducing the game vid-
eo resolution in stereoscopic games has less of an impact than with monoscopic
games, as long as the texture and antialiasing filters are kept optimal.
In this chapter, we focus on creating 3D scenes by using distinct cameras. It
is also possible to reconstruct the 3D scene using a single camera and generate
the parallax from the depth map and color separation, which can be performed
very efficiently on modern GPUs
1
[Carucci and Schobel 2010]. The stereoscopic
image can be created by rendering an image from one view-projection matrix,
which can then be projected pixel by pixel to a second view-projection matrix
using both the depth map and color information generated by the single view.
One of the motivations behind this approach is to keep the impact of stereoscopic
rendering as low as possible to avoid compromises in terms of resolution, details,
or frame rate.
11.9VisualQuality
Some of the techniques used in monoscopic games to improve run-time perfor-
mance, such as view-dependent billboards, might not work very well for close
objects, as the left and right quads would face their own cameras at different an-
gles. It is also important to avoid scintillating pixels as much as possible. There-
1
For example, see http://www.trioviz.com/.