This is a recursive structure. Given a Tri or Vert data the entire data of on the mesh can be found step by step.
I am a little confused as to why (or if) this is memory efficient. It seems to me that the Tri struct and Vert struct would have pointers to each other? I might be understanding wrong, but it seems as there will be redundant storage.
Which triangle does the Vert struct reference? It seems like a single Vert could reference multiple triangles, but that's not accounted for here.
@ dbuer, by my guess, it should be corresponding to the triangle with same index: for example, v would reference to t.