xnaFan's Blog

I once implemented the A* (A-star) pathfinding algorithm in Java, and was ready to do it again in C# for the Klima Konflikt game, but while Googling a bit for referenceimplementations I stumbled across Eric Lippert's very, very elegant solution.
He has basically created a class with a static generic method which will pathfind on anything if you just supply:

1) Items which can tell what their neighbors are - by implementing:
interface IHasNeighbours
{
IEnumerable Neighbours { get; }
}
2) A "Begin" and "End" item
3) A function which gives an estimate on the expected distance from an item to an item (WalledTiles in my case).
The distance can be calculated easily using the Pythagorean theorem.
4) [optional] A function which returns a cost for a tile (based on a weighting system you decide).

Here's the signature for the method:

static public Path FindPath(
Node start, Node destination,
Func distance,
Func estimate)
where Node : IHasNeighbours

It took me 20 minutes to implement, just because I am fairly new to the idea of the Func keyword. Thank you Jesper for walking me through it
Pathfinding takes approximately 46 ms on our 10x10 tile board.

Screenshot from the current version of the game

A very, very elegant solution - thanks Eric!