Splitting them from one array into separate allows us to then reliably pick how each asset should be presented. Also lets us unhardcode some checks like "if file is .vxl ... else is sprite".
Each successive value of BlockedByActor is a superset of the previous value. Having a mixed up order of values in PathSearchOrder is not useful.
In the previous ordering, if a search for Immovable failed to find a path, it would then attempt Stationary. However Stationary is *more* restrictive then Immovable. If Immovable failed, there is no way Stationary could succeed. This means the search for Stationary is wasted effort.
In the fixed ordering, we try Stationary first. In the fixed ordering there are no pointless searches. Every search might succeed where the previous one failed and is therefore useful to try.
The path cache was originally a moderate benefit, but over time a couple of things have conspired against it:
- Only paths with BlockedByActor.None are cached. Originally all paths regardless of blocking were cached but this was deemed unacceptable due to potentially returning outdated paths as actors move about. Paths with BlockedByActor.None are only invalidated if terrain conditions change, which are rarer.
- Move will try and find a path 4 times, trying with a different BlockedByActor check each time. BlockedByActor.None is the last check and only reached if the other searches fail. This is a rare scenario.
Overall, this means the hit rate for the cache is almost non-existent. Given the constraints on path validity it seems unlikely that the hit rate could be improved significantly, therefore it seems reasonable to remove the cache entirely to remove the overhead of cache management.
- Remove functionality for tracking cells considered during the search, as nothing relies on this.
- Rename various parameters in the expand function to closer match naming of fields used in CellInfo, intended to improve clarity.
- Make Status the first field.
- Rename EstimatedTotal to EstimatedTotalCost to make it clearer it has the same unit as the CostSoFar field.
- Rename PreviousPos to PreviousNode as node terminology is a better match for usage.
Firstly, when dealing with maps with height discontinuities, the neighbouring cells we need to search are more that the set we need to search on flat maps. We ensure that as we traverse a map with varying height, we now consider cells "behind" us that may have become accessible due to a height change.
Secondly, when considering connections available via Custom Movement Layers, make sure the target cell on the new layer is actually enterable. Previously this cell would be reported as a valid connection, even if it wasn't actually possible to enter the cell as it was blocked. We also apply the same optimization of ignoring already closed cells.
- Stream lines in as memory rather than needing to realise a string for each line, via a new method in StreamExts.
- Use span to avoid string allocations during parsing until we want to realise the node itself, in MiniYaml.FromLines.
- Change several callsites to use the streaming extension method rather than string method where possible.
As there are few custom movement layers, using an array is good for improving lookup speed. Additionally, we can simplify some code by reserving index 0 of the array for the ground layer. Code that needs to maintain a state for the ground layer and every custom movement layer can now maintain a flat array of state using index 0 for the ground layer, and the the ICustomMovementLayer.Index for the custom movement layer. This removes a lot of ternary statements checking for the ground layer special case.
