If you use a modeling program, you will not have to deal with the intricacies of the definitions of these objects much. However, from time to time you may need to get into the details, so some background is in order. If you are an old hand at computer graphics, you may already know a lot of this. I do include some practical advice on how best to get them into React VR, so it would be good to review.

A polygon is an n-sided object composed of vertices (points), edges, and faces. A face can face in or out or be double sided. For most real-time VR, we use single–sided polygons; we noticed this when we first placed a plane in the world and, depending on the orientation, you may not see it. 

To really show how this all works, I'm going to show the internal format of an OBJ file. Normally, you won't hand edit these — we are beyond the days of VR constructed with a few thousand polygons (my first VR world had a train that represented...