Change A* implementation to use a Grid interface

Controls/PathFinding/2dTileBasedPathFinding/GridI.cs

@@ -0,0 +1,21 @@
+/**
+ * Represent a grid of nodes we can search paths on.
+ * Based on code and tutorial by Sebastian Lague (https://www.youtube.com/channel/UCmtyQOKKmrMVaKuRXz02jbQ).
+ *   
+ * Author: Ronen Ness.
+ * Since: 2016. 
+*/
+using System.Collections.Generic;
+
+namespace NesScripts.Controls.PathFind {
+
+    /// <summary>
+    /// A 2D grid of nodes we use to find paths with the PathFinding class.
+    /// The grid supplies Nodes which mark tiles with traversal costs.
+    /// The grid can be square or hexagonal (using offset coordinate system).
+    /// </summary>
+    public interface GridI {
+        Node GetNode (int x, int y);
+        IEnumerable<Node> GetNeighbours (Node currentNode, Pathfinding.DistanceType distance);
+    }
+}

Controls/PathFinding/2dTileBasedPathFinding/PathFinding.cs

@@ -37,13 +37,13 @@ public enum DistanceType
         /// <summary>
         /// Find a path between two points.
         /// </summary>
-        /// <param name="grid">Grid to search.</param>
+        /// <param name="grid">GridI to search.</param>
         /// <param name="startPos">Starting position.</param>
 		/// <param name="targetPos">Ending position.</param>
         /// <param name="distance">The type of distance, Euclidean or Manhattan.</param>
         /// <param name="ignorePrices">If true, will ignore tile price (how much it "cost" to walk on).</param>
         /// <returns>List of points that represent the path to walk.</returns>
-		public static List<Point> FindPath(Grid grid, Point startPos, Point targetPos, DistanceType distance = DistanceType.Euclidean, bool ignorePrices = false)
+		public static List<Point> FindPath(GridI grid, Point startPos, Point targetPos, DistanceType distance = DistanceType.Euclidean, bool ignorePrices = false)
         {
             // find path
             List<Node> nodes_path = _ImpFindPath(grid, startPos, targetPos, distance, ignorePrices);
@@ -69,10 +69,10 @@ public static List<Point> FindPath(Grid grid, Point startPos, Point targetPos, D
         /// <param name="distance">The type of distance, Euclidean or Manhattan.</param>
         /// <param name="ignorePrices">If true, will ignore tile price (how much it "cost" to walk on).</param>
         /// <returns>List of grid nodes that represent the path to walk.</returns>
-        private static List<Node> _ImpFindPath(Grid grid, Point startPos, Point targetPos, DistanceType distance = DistanceType.Euclidean, bool ignorePrices = false)
+        private static List<Node> _ImpFindPath(GridI grid, Point startPos, Point targetPos, DistanceType distance = DistanceType.Euclidean, bool ignorePrices = false)
         {
-            Node startNode = grid.nodes[startPos.x, startPos.y];
-            Node targetNode = grid.nodes[targetPos.x, targetPos.y];
+            Node startNode = grid.GetNode(startPos.x, startPos.y);
+            Node targetNode = grid.GetNode(targetPos.x, targetPos.y);
 
             List<Node> openSet = new List<Node>();
             HashSet<Node> closedSet = new HashSet<Node>();
@@ -127,7 +127,7 @@ private static List<Node> _ImpFindPath(Grid grid, Point startPos, Point targetPo
         /// <param name="startNode">Starting node.</param>
         /// <param name="endNode">Ending (target) node.</param>
         /// <returns>Retraced path between nodes.</returns>
-        private static List<Node> RetracePath(Grid grid, Node startNode, Node endNode)
+        private static List<Node> RetracePath(GridI grid, Node startNode, Node endNode)
         {
             List<Node> path = new List<Node>();
             Node currentNode = endNode;