When I said it'd be done when it was done? Well, it's done.

Here.

That is, the nasty fucking difficult bits are done. Ironically the solution was SO FREAKING SIMPLE, and worse: I TRIED IT EARLIER, but didn't quite get it right.

Once I had trees and their (very special - see if you can figure it out) shadows mapping onto the world, the rest was easy. For extra fun, try to find the sign. It's meant to start in the same place each time, but it doesn't.