Well, this essentially allows you to move around a 3d forest. This style of rendering is great for sprites, but makes it harder to create a complex environment. The lens_angle variable changes how much the camera can see. The wider the view, the more the trees look distorted when rotating, like a fish-eye lens. However, with a smaller value, it simulates tunnel vision, as the view window is much smaller. A value of 40 looks about right. Dynamic lens angles could be used rather well in a game- for example, a lens value of 40 could be used when shooting things with a machine gun, and a value of 20 could be used to simulate the scope of a sniper rifle, along with a visual of a crosshair.
