implement GridState code with accompanying refactoring, general fixes and cleanup, GetNode, IsValid, RecordState, GetStates etc.

Paths/Assets/Scripts/Algorithms/AStar.cs

@@ -1,24 +1,33 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Linq;
 using System.Numerics;
-using Algorithms;
 
+namespace Algorithms {
     public class AStar : IPathfinding {
         private NodeGrid _nodeGrid;
 
         private Stack<Node> _path;
         private List<Node> _openList;
         private List<Node> _closedList;
+        private List<GridState> _states;
+
+        private Vector2 _start;
+        private Vector2 _end;
 
         public AStar(NodeGrid nodeGrid) {
             this._nodeGrid = nodeGrid;
+            _states = new List<GridState>();
         }
 
-    public Tuple<List<NodeGrid>, Stack<Node>> FindPath(Vector2 Start, Vector2 End) {
+        public Stack<Node> FindPath(Vector2 Start, Vector2 End) {
+            this._start = Start;
+            this._end = End;
+
             var start = new Node(Start, true);
             var end = new Node(End, true);
             
+            RecordState();
+
             _path = new Stack<Node>();
             _openList = new List<Node>();
             _closedList = new List<Node>();
@@ -31,8 +40,9 @@ public class AStar : IPathfinding {
                 current = _openList[0];
                 _openList.Remove(current);
                 _closedList.Add(current);
-            List<Node> adjacentNodes = this._nodeGrid.GetAdjacentNodes(current);
+                RecordState();
 
+                IEnumerable<Node> adjacentNodes = this._nodeGrid.GetAdjacentNodes(current);
 
                 foreach (Node n in adjacentNodes) {
                     if (!_closedList.Contains(n) && n.Walkable) {
@@ -40,8 +50,11 @@ public class AStar : IPathfinding {
                             n.Parent = current;
                             n.DistanceToTarget = NodeGrid.Manhattan(n, end);
                             n.Cost = n.Weight + n.Parent.Cost;
+
                             _openList.Add(n);
-                        _openList = _openList.OrderBy(node => node.F).ToList<Node>();
+                            _openList = _openList.OrderBy(node => node.F).ToList();
+
+                            RecordState();
                         }
                     }
                 }
@@ -63,6 +76,24 @@ public class AStar : IPathfinding {
             return _path;
         }
 
-    private StateGrid compileState() {
+        /// <summary>
+        /// Records the current state of the pathfinding algorithm in the grid.
+        /// </summary>
+        public void RecordState() {
+            // TODO: Record basic grid node types
+            // TODO: Record timing information
+            // TODO: Record pathfinding state information (stages, heuristic, statistical info)
+            this._states.Add(
+                new GridState(this._nodeGrid, this._openList, this._closedList, _start, _end, _path)
+            );
+        }
+
+        /// <summary>
+        /// Returns the current list of grid states of the pathfinding algorithm.
+        /// </summary>
+        /// <returns>A list of GridState objects representing the pathfinding algorithm's progress</returns>
+        public List<GridState> GetStates() {
+            return this._states;
+        }
     }
 }

Paths/Assets/Scripts/Algorithms/NodeGrid.cs

@@ -2,14 +2,12 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Numerics;
-using Algorithms;
-using NUnit.Framework.Constraints;
-using UnityEngine.SocialPlatforms;
 
+namespace Algorithms {
     public class NodeGrid {
         private List<List<Node>> grid;
-    private readonly int _width;
-    private readonly int _height;
+        public readonly int Width;
+        public readonly int Height;
 
         public NodeGrid(int width, int height) {
             if (width <= 0)
@@ -29,32 +27,51 @@ public class NodeGrid {
                 this.grid.Add(list);
             }
 
-        this._width = width;
-        this._height = height;
+            this.Width = width;
+            this.Height = height;
         }
 
         public NodeGrid(List<List<Node>> grid) {
             this.grid = grid;
 
-        this._height = this.grid[0].Count;
-        this._width = this.grid.Count;
+            this.Height = this.grid[0].Count;
+            this.Width = this.grid.Count;
         }
 
-    public List<Node> GetAdjacentNodes(Node node) {
+        public IEnumerable<Node> GetAdjacentNodes(Node node) {
             List<Node> temp = new List<Node>();
 
             int row = (int) node.Position.Y;
             int col = (int) node.Position.X;
 
-        if (row + 1 < _height) temp.Add(this.grid[col][row + 1]);
+            if (row + 1 < Height) temp.Add(this.grid[col][row + 1]);
             if (row - 1 >= 0) temp.Add(this.grid[col][row - 1]);
             if (col - 1 >= 0) temp.Add(this.grid[col - 1][row]);
-        if (col + 1 < _width) temp.Add(this.grid[col + 1][row]);
+            if (col + 1 < Width) temp.Add(this.grid[col + 1][row]);
 
             return temp;
         }
 
+        public bool IsValid(int x, int y) {
+            return x > 0 && x < this.Width && y > 0 && y < this.Height;
+        }
+        
+        /// <summary>
+        /// Retrieves a node at a given coordinate.
+        /// </summary>
+        /// <param name="x">the X (column) coordinate</param>
+        /// <param name="y">the Y (row) coordinate</param>
+        /// <returns>A Node object</returns>
+        /// <exception cref="ArgumentOutOfRangeException">when the coordinate given does not exist on the grid</exception>
+        public Node GetNode(int x, int y) {
+            if(!IsValid(x, y))
+                throw new ArgumentOutOfRangeException();
+            
+            return this.grid[x][y];
+        }
+
         public static float Manhattan(Node first, Node second) {
             return Math.Abs(first.Position.X - second.Position.X) + Math.Abs(first.Position.Y - second.Position.Y);
         }
     }
+}

Paths/Assets/Scripts/GridState.cs

@@ -0,0 +1,40 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+using Algorithms;
+
+public class GridState {
+    private List<List<GridNodeType>> _grid;
+
+    public GridState(NodeGrid grid, IEnumerable<Node> seen, IEnumerable<Node> expanded, Vector2 start, Vector2 end, IReadOnlyCollection<Node> path) {
+        this._grid = new List<List<GridNodeType>>(grid.Width);
+
+        // Add walls and empty tiles
+        foreach (var x in Enumerable.Range(0, grid.Width - 1)) {
+            this._grid.Add(new List<GridNodeType>(grid.Height));
+            foreach (var y in Enumerable.Range(0, grid.Height - 1)) {
+                Node node = grid.GetNode(x, y);
+                this._grid[x].Add(!node.Walkable ? GridNodeType.Wall : GridNodeType.Empty);
+            }
+        }
+
+        // Add 'seen' tiles
+        foreach (Node seenNode in seen) {
+            this._grid[(int) seenNode.Position.X][(int) seenNode.Position.Y] = GridNodeType.Seen;
+        }
+
+        // Add 'expanded' tiles
+        foreach (Node expandedNode in expanded) {
+            this._grid[(int) expandedNode.Position.X][(int) expandedNode.Position.Y] = GridNodeType.Expanded;
+        }
+
+        // Set start and end tiles
+        this._grid[(int) start.X][(int) start.Y] = GridNodeType.Start;
+        this._grid[(int) end.X][(int) end.Y] = GridNodeType.End;
+
+        // Add 'path' tiles
+        if (path != null)
+            foreach (Node pathNode in path)
+                this._grid[(int) pathNode.Position.X][(int) pathNode.Position.Y] = GridNodeType.Path;
+    }
+}

Paths/Assets/Scripts/GridState.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 1a26aa7e514043e8911382088176258b
+timeCreated: 1604887099

Paths/Assets/Scripts/Pathfinding.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Numerics;
 using Algorithms;
 
@@ -13,5 +12,12 @@ public interface IPathfinding {
     /// <param name="start">The position from which pathfinding begins</param>
     /// <param name="end">The position trying to be found via pathfinding</param>
     /// <returns>A List of NodeGridGrid objects representing the timeline of Pathfinding</returns>
-    Tuple<List<NodeGrid>, Stack<Node>> FindPath(Vector2 start, Vector2 end);
+    Stack<Node> FindPath(Vector2 start, Vector2 end);
+
+    /// <summary>
+    /// Records the current state of the pathfinding algorithm. Internal usage only.
+    /// </summary>
+    void RecordState();
+
+     List<GridState> GetStates();
 }