I skimmed over that article..it was interesting, though I would have to think about how to approach it.

I know that Josef's Tear has a fog system that supposedly interacts with the player. I'm not too concerned about that level of realism, but it would be something to see I'm sure.

I'm just trying to give a nice simulation of light beams coming through windows without resorting to sprite shafts. That works if you have a limited view of the window; otherwise it becomes obvious that a billboard is being used and will destroy the illusion.