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Adventure Game #002: A* Pathfinding

A* Pathfinding is kinda an essential to the gaming world, it lets you player move around, it helps AI both in NPC and Enemies, it can help validate paths, mazes, and dungeons, etc. so naturally Pathfinding is something that I had to implement.

Years ago in college I developed the algorithm for A* Pathfinding, however it was more of an theoretical exercise than a piece of code I could use, so with the help of and my old notes I put this together!

The code is simple, give the object a 2D char array, the start location, and the end location and it will spit you out a node with a recursive parent to take you to the end location.

Diagonal movement costs 1.4
vertical/horizontal movement cost 1

Maps only work with (0,ymax) as the top left corner and (xmax,0) as the bottom right corner
ArgumentOutOfRangeException if the end point is unreachable
These limitations will be solved in the next iteration of the A* Pathfinding post

s = start
o = open space
c = closed space
e = end

The following is the output:
from start, move to (0,2) then (1,2) ..... ending at (0,0)

How It Works

When calling GetShortestPath() with a char array map, the class will do the following steps:
1. create open/closed lists to keep track of visited nodes
2. create a map, get the start/end position, and set all the h values
3. LOOP:
3A. Get all adjactent open nodes
3B. Get the node with the smallest F (Movement Cost + Distance from end) and set to parent
4. when the current node is the end position return the end position and recursivly call node.ParentNode to get a path from start to end.

take a look at the AstarPathfinding class to check out the whole process (including all the private functions that help make the whole thing possible)

Downloads & Links

Source code: AstarPathfinding.cs


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