From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: chase <chasewhip20@gmail.com>
Date: Wed, 2 Dec 2020 22:43:39 -0800
Subject: [PATCH] add per world spawn limits

Taken from #2982. Credit to Chasewhip8

diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index db4aed53ce28393ac34c06753647cbe1322e89c6..54a2f43e568b0104571abcb5d84aac35ddde3cd7 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -53,6 +53,11 @@ public class PaperWorldConfig {
 
             set("despawn-ranges.soft", null);
             set("despawn-ranges.hard", null);
+
+            set("spawn-limits.monsters", null);
+            set("spawn-limits.animals", null);
+            set("spawn-limits.water-animals", null);
+            set("spawn-limits.water-ambient", null);
         }
 
         if (needsSave) {
@@ -683,6 +688,21 @@ public class PaperWorldConfig {
         zombieVillagerInfectionChance = getDouble("zombie-villager-infection-chance", zombieVillagerInfectionChance);
     }
 
+    public Reference2IntMap<MobCategory> perWorldSpawnLimits = new Reference2IntOpenHashMap<>(net.minecraft.world.level.NaturalSpawner.SPAWNING_CATEGORIES.length);
+    private void perWorldSpawnLimits() {
+        perWorldSpawnLimits.defaultReturnValue(-1);
+        if (PaperConfig.version < 24) {
+            // ambient category already had correct name
+            perWorldSpawnLimits.put(MobCategory.MONSTER, getInt("spawn-limits.monsters", -1, false));
+            perWorldSpawnLimits.put(MobCategory.CREATURE, getInt("spawn-limits.animals", -1, false));
+            perWorldSpawnLimits.put(MobCategory.WATER_CREATURE, getInt("spawn-limits.water-animals", -1, false));
+            perWorldSpawnLimits.put(MobCategory.WATER_AMBIENT, getInt("spawn-limits.water-ambient", -1, false));
+        }
+        for (MobCategory value : net.minecraft.world.level.NaturalSpawner.SPAWNING_CATEGORIES) {
+            perWorldSpawnLimits.put(value, getInt("spawn-limits." + value.getName(), perWorldSpawnLimits.getInt(value)));
+        }
+    }
+
     public int lightQueueSize = 20;
     private void lightQueueSize() {
         lightQueueSize = getInt("light-queue-size", lightQueueSize);
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
index e2f88425ea748384af18b126c6478a58a3eba176..1d0eb961e3abc980845ff3ecc8a790a98c55e49c 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -221,6 +221,13 @@ public class CraftWorld extends CraftRegionAccessor implements World {
         this.biomeProvider = biomeProvider;
 
         this.environment = env;
+        // Paper start - per world spawn limits
+        for (SpawnCategory spawnCategory : SpawnCategory.values()) {
+            if (CraftSpawnCategory.isValidForLimits(spawnCategory)) {
+                setSpawnLimit(spawnCategory, this.world.paperConfig.perWorldSpawnLimits.getInt(CraftSpawnCategory.toNMS(spawnCategory)));
+            }
+        }
+        // Paper end
     }
 
     @Override