Shroud / fog of war

[tgjones]

PartitionCellManager is the thing that stores "partition cell" visibility for each player. It also stores a list of "shroud reveals" which can be generated by scripts. From these partition cells and shroud reveals, it needs to generate a shroud / fog of war texture for the local player.

Here's what I know about partition cell "state" values:

• 1 means the player has never seen this cell (so it's black in the shroud texture)
• 0 means the player has previously seen this cell, but now can't see it (so semi-transparent in the shroud texture, and also the objects underneath should be ghost objects, but that's a different topic)
• Negative numbers - the cell is visible. The higher the negative number, the more visible that cell is, because it has more units, or had more units, in that cell. When units move into a cell, the state value is decremented. When units move out of a cell, then after a timeout, the state value is incremented.