[Player] Add AI Pathfinding on a 2D grid to the player character

Assets/External/AstarPathfindingProject/Utilities/GraphUpdateUtilities.cs

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+using System.Collections.Generic;
+using Pathfinding.Util;
+
+namespace Pathfinding {
+	/// <summary>
+	/// Contains useful functions for updating graphs.
+	/// This class works a lot with the GraphNode class, a useful function to get nodes is <see cref="AstarPath.GetNearest"/>.
+	///
+	/// See: <see cref="AstarPath.GetNearest"/>
+	/// See: <see cref="Pathfinding.PathUtilities"/>
+	///
+	/// \since Added in 3.1
+	///
+	/// \ingroup utils
+	/// </summary>
+	public static class GraphUpdateUtilities {
+		/// <summary>
+		/// Updates graphs and checks if all nodes are still reachable from each other.
+		/// Graphs are updated, then a check is made to see if the nodes are still reachable from each other.
+		/// If they are not, the graphs are reverted to before the update and false is returned.\n
+		/// This is slower than a normal graph update.
+		/// All queued graph updates and thread safe callbacks will be flushed during this function.
+		///
+		/// Returns: True if the given nodes are still reachable from each other after the guo has been applied. False otherwise.
+		///
+		/// <code>
+		/// var guo = new GraphUpdateObject(tower.GetComponent<Collider>().bounds);
+		/// var spawnPointNode = AstarPath.active.GetNearest(spawnPoint.position).node;
+		/// var goalNode = AstarPath.active.GetNearest(goalPoint.position).node;
+		///
+		/// if (GraphUpdateUtilities.UpdateGraphsNoBlock(guo, spawnPointNode, goalNode, false)) {
+		///     // Valid tower position
+		///     // Since the last parameter (which is called "alwaysRevert") in the method call was false
+		///     // The graph is now updated and the game can just continue
+		/// } else {
+		///     // Invalid tower position. It blocks the path between the spawn point and the goal
+		///     // The effect on the graph has been reverted
+		///     Destroy(tower);
+		/// }
+		/// </code>
+		/// </summary>
+		/// <param name="guo">The GraphUpdateObject to update the graphs with</param>
+		/// <param name="node1">Node which should have a valid path to node2. All nodes should be walkable or false will be returned.</param>
+		/// <param name="node2">Node which should have a valid path to node1. All nodes should be walkable or false will be returned.</param>
+		/// <param name="alwaysRevert">If true, reverts the graphs to the old state even if no blocking occurred</param>
+		public static bool UpdateGraphsNoBlock (GraphUpdateObject guo, GraphNode node1, GraphNode node2, bool alwaysRevert = false) {
+			List<GraphNode> buffer = ListPool<GraphNode>.Claim();
+
+			buffer.Add(node1);
+			buffer.Add(node2);
+
+			bool worked = UpdateGraphsNoBlock(guo, buffer, alwaysRevert);
+			ListPool<GraphNode>.Release(ref buffer);
+			return worked;
+		}
+
+		/// <summary>
+		/// Updates graphs and checks if all nodes are still reachable from each other.
+		/// Graphs are updated, then a check is made to see if the nodes are still reachable from each other.
+		/// If they are not, the graphs are reverted to before the update and false is returned.
+		/// This is slower than a normal graph update.
+		/// All queued graph updates will be flushed during this function.
+		///
+		/// Returns: True if the given nodes are still reachable from each other after the guo has been applied. False otherwise.
+		/// </summary>
+		/// <param name="guo">The GraphUpdateObject to update the graphs with</param>
+		/// <param name="nodes">Nodes which should have valid paths between them. All nodes should be walkable or false will be returned.</param>
+		/// <param name="alwaysRevert">If true, reverts the graphs to the old state even if no blocking occurred</param>
+		public static bool UpdateGraphsNoBlock (GraphUpdateObject guo, List<GraphNode> nodes, bool alwaysRevert = false) {
+			bool worked;
+
+			// Pause pathfinding while modifying the graphs
+			var graphLock = AstarPath.active.PausePathfinding();
+
+			try {
+				// Make sure any pending graph updates have been done before we start
+				AstarPath.active.FlushGraphUpdates();
+
+				// Make sure all nodes are walkable
+				for (int i = 0; i < nodes.Count; i++) if (!nodes[i].Walkable) return false;
+
+				// Track changed nodes to enable reversion of the guo
+				guo.trackChangedNodes = true;
+
+				AstarPath.active.UpdateGraphs(guo);
+
+				// Update the graphs immediately
+				AstarPath.active.FlushGraphUpdates();
+
+				// Check if all nodes are in the same area and that they are walkable, i.e that there are paths between all of them
+				worked = PathUtilities.IsPathPossible(nodes);
+
+				// If it did not work, revert the GUO
+				if (!worked || alwaysRevert) {
+					guo.RevertFromBackup();
+					// Recalculate connected components
+					AstarPath.active.hierarchicalGraph.RecalculateIfNecessary();
+				}
+			} finally {
+				graphLock.Release();
+			}
+
+			// Disable tracking nodes, not strictly necessary, but will slightly reduce the cance that some user causes errors
+			guo.trackChangedNodes = false;
+
+			return worked;
+		}
+	}
+}