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A-star is a path finding algorithm, written in PHP. It can find the shortest path between two points in a two dimensional array by using different heuristics.
first create a two dimensional array for your map
each key represent the x and y position of the map. each value of the array represents the costs, A-star tries to find a way with lowest costs. you can use negative keys if your map requires it.
next convert the array to a Grid, a Grid is a collection of Nodes.
now you can fetch nodes from the Grid like so
at the end pass the grid to the astar and search for the shortests path
by default diagonal directions are disabled, they can be enabled like so
as soon as the diagonal option is enabled, the algorithm use the Manhattan heuristic to find the shortest path.
Manhattan is not precise but the caluclation costs are low, however you can use another heuristics like Diagonal or Euclidean with following code.
you can also create a custom heuristic.
there are cases where you want to block a specific path completly, independant of the costs, you can do so with following code
this basicly means that in the initial map
the values 3 and 2 cannot be passed.
Please feel free to make pull requests, there is still place for improvement, the Grid contains a two dimensional array which might be replaced by an SplFixedArray or something similar.
Run the tests to be sure nothing break.
A-Star is free software distributed under the terms of the MIT license.