Bounding boxes and shadows added.

I’ve been busy refactoring things into more modularized code.

Also, the scene now uses bounding boxes around the tiles so that not visible tiles are culled, reducing the number of draw calls.

The default Babylon.js framework provided poisson sampled (4-tap) PCF shadows are also enabled.

The camera now follows the player character object, it’s the grey rectangular prism, which we can now move around with the keyboard.