3D camera, perspective, and head rotation

As awesome as this is (ha ha), our app is kind of boring and not very Cardboard-like. Specifically, it's stereoscopic (dual views) and has lens distortion, but it's not yet a 3D perspective view and it doesn't move with your head. We're going to fix this now.

Welcome to the matrix

We can't talk about developing for virtual reality without talking about matrix mathematics for 3D computer graphics.

What is a matrix? The answer is out there, Neo, and it's looking for you, and it will find you if you want it to. That's right, it's time to learn about the matrix. Everything will be different now. Your perspective is about to change.

We're building a three-dimensional scene. Each location in space is described by the X, Y, and Z coordinates. Objects in the scene may be constructed from X, Y, and Z vertices. An object can be transformed by moving, scaling, and/or rotating its vertices. This transformation can be represented mathematically with a matrix of 16...