baseline: OpenMU upstream b5a0961 (fresh source)

src/Pathfinding/Readme.md

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+# Pathfinding
+
+This projects includes an a-star pathfinding algorithm, specifically for maps
+which have a maximum size of 256 x 256. This limitation arises by using byte
+fields for the coordinates, which saves some memory.
+There are a few heuristics available but by default the PathFinder uses NoHeuristic
+which is basically equal to using the Dijkstra algorithm.
+
+## Priority Queue
+
+There are two implementations of a priority queue of the Open-List: BinaryMinHeap
+and IndexedLinkedList.
+I suggest using the BinaryMinHeap because it's commonly used and it's hard to get
+IndexedLinkedList working faster under real circumstances.
+The reason is, that it's pretty hard to get the index fast under all conditions,
+because the expected open list lengths and estimated costs are always different.
+
+## Scoped
+
+The implementation can be used in a scoped way, which means that the pathfinder
+is only used for a scoped area of the map. This is useful if you want to calculate
+paths very quickly and you know that the path is only needed in a small area.
+You can read about that on my blog post: [Optimized Pathfinding](https://munique.net/optimizing-pathfinding/).
+
+## Safezones
+
+Safezones are areas on the map where usually no path should be calculated, except
+for special NPCs like guards. By default, the pathfinder will not calculate paths
+on the safezone tiles. You can change this behavior by passing the parameter
+`includeSafezone`. The safezones are encoded into the grid cost values as the
+highest bit.
+
+## Pre-Calculation
+
+In the sub-folder PreCalculation includes a pathfinder which makes use of
+pre-calculated paths. It's not used yet by OpenMU and needs some further testing.
+
+For more information, visit <http://www.gamedev.net/page/resources/_/technical/artificial-intelligence/precalculated-pathfinding-revisited-r1939>.
+
+## Further optimizations
+
+If we find out that the current implementation is too slow, we could implement
+[Jump Point Search](http://www.gdcvault.com/play/1022094/JPS-Over-100x-Faster-than).