The IRemoveFrozenActor interface is replaced with a Remove method on FrozenActorLayer. IRemoveFrozenActor is a performance problem for FrozenActorLayer.Tick as it incurs a large cache miss penalty in order to load and enumerate the array of these interfaces for every frozen actor. Instead, we invert control and allow traits to remove frozen actors directly which eliminates the performance penalty.
The size of the bounds was too small (as rectangle has exclusive edges on the right and bottom). This meant some intersection tests would fail and thus the frozen actor was not found when searching the partition bins.
Track changes in the shroud in a spatial partition in frozen actor layer. This allows us to run the expensive visibility updates only on frozen actors with a footprint in affected partitions, rather than on all frozen actors every time.
This can be used to avoid several lookups for these traits, as well as allow Actor to provide specialised methods to deal with target types efficiently. This also reduces some code duplication.
The previous lazy rendering means the snapshot of the render state might be more up to date then when the frozen actor actually did become visible. Now, we take this snapshot as soon as needed. We still retain the performance of only doing this rendering when needed by avoiding extra rendering until the visibility cycles again.
In places where arrays were being treated as a set, just create a set directly. This reveals the intention of such collections better, and also improves performance by allowing set based methods to be used.
Previously actors that could be frozen under fog but were currently visible would be rendered by the frozen under fog system constantly in order to keep a copy of the renderables ready to go for the frozen counterpart when the actor became invisible. Instead, we now delay this extra rendering until the actor actually becomes invisible. This eliminates the wasted rendering to generate renderables that were never used.
The FrozenUnderFog.Tick method will now reuse the calculation do by the frozen actor when it had to calculate its visibility, this prevents it having to re-do the fairly expensive visibility calculation.
To resolve the ambiguity introduced when the introduction of isometric maps meant that cell and map coordinates were no longer equivalent, a new type has been introduced so they can each be represented separately.
