#201 - Added CollectTilemapSourcesCache2d extension (#202)

* #201 - Added CollectTilemapSourcesCache2d extension which caches individual tilemap tile sources for increased navmesh update performance

NavMeshComponents/Scripts/CollectTilemapSourcesCache2d.cs

@@ -0,0 +1,88 @@
+using NavMeshPlus.Components;
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.AI;
+using UnityEngine.Tilemaps;
+
+namespace NavMeshPlus.Extensions
+{
+    [ExecuteAlways]
+    [AddComponentMenu("Navigation/Navigation CacheTilemapSources2d", 30)]
+    public class CollectTilemapSourcesCache2d : NavMeshExtension
+    {
+        [SerializeField] private Tilemap _tilemap;
+        [SerializeField] private NavMeshModifier _modifier;
+        [SerializeField] private NavMeshModifierTilemap _modifierTilemap;
+
+        private List<NavMeshBuildSource> _sources;
+        private Dictionary<Vector3Int, int> _lookup;
+        private Dictionary<TileBase, NavMeshModifierTilemap.TileModifier> _modifierMap;
+
+        protected override void Awake()
+        {
+            _modifier ??= _tilemap.GetComponent<NavMeshModifier>();
+            _modifierTilemap ??= _tilemap.GetComponent<NavMeshModifierTilemap>();
+            _modifierMap = _modifierTilemap.GetModifierMap();
+            Order = -1000;
+            base.Awake();
+        }
+
+        private void OnTilemapTileChanged(Tilemap tilemap, Tilemap.SyncTile[] syncTiles)
+        {
+            if (tilemap == _tilemap)
+            {
+                foreach (Tilemap.SyncTile syncTile in syncTiles)
+                {
+                    Vector3Int position = syncTile.position;
+                    if (syncTile.tile != null && _modifierMap.TryGetValue(syncTile.tile, out NavMeshModifierTilemap.TileModifier tileModifier))
+                    {
+                        int i = _lookup[position];
+                        NavMeshBuildSource source = _sources[i];
+                        source.area = tileModifier.area;
+                        _sources[i] = source;
+                    }
+                    else if (_modifier.overrideArea)
+                    {
+                        int i = _lookup[position];
+                        NavMeshBuildSource source = _sources[i];
+                        source.area = _modifier.area;
+                        _sources[i] = source;
+                    }
+                }
+            }
+        }
+
+        public AsyncOperation UpdateNavMesh(NavMeshData data)
+        {
+            return NavMeshBuilder.UpdateNavMeshDataAsync(data, NavMeshSurfaceOwner.GetBuildSettings(), _sources, data.sourceBounds);
+        }
+
+        public AsyncOperation UpdateNavMesh()
+        {
+            return UpdateNavMesh(NavMeshSurfaceOwner.navMeshData);
+        }
+
+        public override void PostCollectSources(NavMeshSurface surface, List<NavMeshBuildSource> sources, NavMeshBuilderState navNeshState)
+        {
+            _sources = sources;
+            if (_lookup == null)
+            {
+                _lookup = new Dictionary<Vector3Int, int>();
+                for (int i = 0; i < _sources.Count; i++)
+                {
+                    NavMeshBuildSource source = _sources[i];
+                    Vector3Int position = _tilemap.WorldToCell(source.transform.GetPosition());
+                    _lookup[position] = i;
+                }
+            }
+            Tilemap.tilemapTileChanged -= OnTilemapTileChanged;
+            Tilemap.tilemapTileChanged += OnTilemapTileChanged;
+        }
+
+        protected override void OnDestroy()
+        {
+            Tilemap.tilemapTileChanged -= OnTilemapTileChanged;
+            base.OnDestroy();
+        }
+    }
+}