Thought so.
I just made this one, not sure if it's the best way of doing it, still testing... it seems to affect the game performance a little.
And it has some limitations, like: it's not possible to save the fog of war, which means: if the player save the game in a map that has the fog of war, when he load the game the fog of war will be reset like if he never explored the map.
For now it's part of a map plugin that I made and is key to my project, maybe in the future I post it here if no one else make a better one.