Fog of war / Line of sight

UPDATE:
I didn’t have a lot of time to work on this in the last month, but now I should be able to finish.
For the single source of vision I would say I’m almost done. I just need to clean up the blueprints and maybe make some aspects customizable.
But I think the project would benefit a lot from being able to work with more sources of vision. This however is proving to be very hard to do. And I must admit, I seem to be stuck.
Now I need to decide if the single source is enough. This really comes down to what type of game you would want to make using this system.