From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: MrHua269 <mrhua269@gmail.com>
Date: Sat, 8 Mar 2025 21:21:11 +0800
Subject: [PATCH] Paper: Prevent zombie reinforcements loading chunks

Origin: https://github.com/PaperMC/Paper/pull/11945
Co-authored by: Newwind <support@newwindserver.com>
As part of: Paper (https://github.com/PaperMC/Paper/blob/2ae1f05336d0f13b646e6c284f83ded16aae84ff/patches/server/1045-Prevent-zombie-reinforcements-loading-chunks.patch)
Licensed under: GPL-3.0 (https://github.com/PaperMC/Paper/blob/fa360aa83657d15e8e803ce55800986f6bff8f70/licenses/GPL.md)

diff --git a/net/minecraft/world/entity/monster/Zombie.java b/net/minecraft/world/entity/monster/Zombie.java
index a23607874a72723914cbfeea0ad1c51236c044d8..14d0758aca54d9a25e369dfa8c89c930f27946c9 100644
--- a/net/minecraft/world/entity/monster/Zombie.java
+++ b/net/minecraft/world/entity/monster/Zombie.java
@@ -352,6 +352,13 @@ public class Zombie extends Monster {
                     int i2 = floor1 + Mth.nextInt(this.random, 7, 40) * Mth.nextInt(this.random, -1, 1);
                     int i3 = floor2 + Mth.nextInt(this.random, 7, 40) * Mth.nextInt(this.random, -1, 1);
                     BlockPos blockPos = new BlockPos(i1, i2, i3);
+
+                    // Paper start - Prevent reinforcement checks from loading chunks
+                    if (this.level().getChunkIfLoadedImmediately(blockPos.getX() >> 4, blockPos.getZ() >> 4) == null) {
+                        continue;
+                    }
+                    // Paper end - Prevent reinforcement checks from loading chunks
+
                     if (SpawnPlacements.isSpawnPositionOk(type, level, blockPos)
                         && SpawnPlacements.checkSpawnRules(type, level, EntitySpawnReason.REINFORCEMENT, blockPos, level.random)) {
                         zombie.setPos(i1, i2, i3);