Shaders about distortionizer

[rpavlik]

FWIW - distortion not yet implemented in OSVR-Unity, OSVR-Unreal, SteamVR-OSVR, or OSVR-MonoGame AFAICT.

[russell-taylor]

When I handed off the distortionizer, it had buttons that the user could use to adjust the centers of projection for the eyes, and I think it only allowed mirror symmetric solutions (left eye X = -right eye X, left eye Y = right eye Y).

OpenCV radial distortion parameters look consistent with the one the distortionizer originally used, which would match the k1 (quadratic) term in OpenCV. There are also 4th and 6th power coefficients available in the numerator and denominator. I was able to get pretty good results with just the quadratic term on the DK2 (with a different parameter for each color).

Good to reduce sqrt() in the shader. Yuval was thinking that should be possible to remove.