Merge pull request #170 from Readixyee/tradeship-caching

Trade ship path caching

src/core/pathfinding/PathFinding.ts

@@ -12,6 +12,8 @@ export class PathFinder {
   private aStar: AStar;
   private computeFinished = true;
 
+  private pathCache: Map<number, TileRef[]> = new Map();
+
   private constructor(
     private game: Game,
     private newAStar: (curr: TileRef, dst: TileRef) => AStar,
@@ -53,6 +55,15 @@ export class PathFinder {
       return { type: PathFindResultType.Completed, tile: curr };
     }
 
+    // make key the same between port a -> b and b -> a
+    const key = curr < dst ? curr * 1_000_000 + dst : dst * 1_000_000 + curr;
+
+    // get the cached path
+    if (this.pathCache.has(key)) {
+      this.path = this.pathCache.get(key)!;
+      return { type: PathFindResultType.NextTile, tile: this.path.shift() };
+    }
+
     if (this.computeFinished) {
       if (this.shouldRecompute(curr, dst)) {
         this.curr = curr;
@@ -72,6 +83,9 @@ export class PathFinder {
         this.path = this.aStar.reconstructPath();
         // Remove the start tile
         this.path.shift();
+
+        // save the path in the cache
+        this.pathCache.set(key, [...this.path]);
         return this.nextTile(curr, dst);
       case PathFindResultType.Pending:
         return { type: PathFindResultType.Pending };