Initial floodSearch impl

island.ts

@@ -35,6 +35,38 @@ class IslandGrid {
     this.data[this.xy(x, y)] = tile;
     console.log(x, y, this.xy(x, y), this.data[this.xy(x, y)]);
   }
+
+  public floodSearch(
+    startPos: number,
+    shouldExpand: (tile: number) => boolean
+  ): number[] {
+    const len = this.data.length;
+    const width = this.width;
+    const seen = new Uint8Array(len);
+
+    const hitPositions: number[] = [];
+
+    function enqueue(pos: number) {
+      if (!seen[pos]) {
+        hitPositions.push(pos);
+        seen[pos] = 1;
+      }
+    }
+
+    enqueue(startPos);
+
+    for (let i = 0; i < hitPositions.length; i++) {
+      const pos = hitPositions[i];
+      if (shouldExpand(this.data[pos])) {
+        enqueue((pos - width) % len);
+        enqueue((pos - 1) % len);
+        enqueue((pos + 1) % len);
+        enqueue((pos + width) % len);
+      }
+    }
+
+    return hitPositions;
+  }
 }
 
 function renderIslands(islands: IslandGrid, cx: CanvasRenderingContext2D) {
@@ -75,6 +107,9 @@ export function IslandApplet() {
   const y = islands.rng();
 
   islands.set(x, y, 1);
+  islands
+    .floodSearch(islands.xy(x, y), (tile) => tile > 0)
+    .forEach((pos) => islands.data[pos]++);
 
   renderIslands(islands, cx);