From 09a4f17270e0d4a8960754ce9b29429c39095187 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 18 Feb 2026 22:12:15 +0000
Subject: [PATCH] =?UTF-8?q?Optimize=20zones=20restoration=20with=20O(n)=20?=
 =?UTF-8?q?map=20lookup=20instead=20of=20O(n=C2=B2)?=
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Co-authored-by: Azgaar <26469650+Azgaar@users.noreply.github.com>
---
 public/modules/ui/heightmap-editor.js | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/public/modules/ui/heightmap-editor.js b/public/modules/ui/heightmap-editor.js
index e5272c35..d98c1c3f 100644
--- a/public/modules/ui/heightmap-editor.js
+++ b/public/modules/ui/heightmap-editor.js
@@ -443,9 +443,16 @@ function editHeightmap(options) {
       Lakes.defineNames();
     }
 
+    const gridToPackMap = new Map();
+    for (const i of pack.cells.i) {
+      const g = pack.cells.g[i];
+      if (!gridToPackMap.has(g)) gridToPackMap.set(g, []);
+      gridToPackMap.get(g).push(i);
+    }
+
     for (const zone of pack.zones) {
       if (!zone.gridCells || !zone.gridCells.length) continue;
-      zone.cells = pack.cells.i.filter(i => zone.gridCells.includes(pack.cells.g[i]));
+      zone.cells = zone.gridCells.flatMap(g => gridToPackMap.get(g) || []);
       delete zone.gridCells;
     }