Currently this shader only supports one light - supporting greater numbers of them could become a performance problem without additional effort put into, say, subdividing the landscape texture. I am trying to determine whether it's worth it to implement such a thing.

But apart from that, shaders give us great freedom in what kind of behavior we want. I suppose we wouldn't want it to be fully additive, for example?

Edit: Hm, also looking at the screenshot again, it seems I again have messed up the brightness level of the background material. Just look closely at the edge between sand and sky...