Paper/patches/server/0336-Only-count-Natural-Spawned-mobs-towards-natural-spaw.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 24 Mar 2019 01:01:32 -0400
Subject: [PATCH] Only count Natural Spawned mobs towards natural spawn mob
 limit

This resolves the super common complaint about mobs not spawning.

This was ultimately a flaw in the vanilla count algorithim that allows
spawners and other misc mobs to count against the mob limit, which are
not bounded, and can prevent the entire world from spawning new.

I believe Bukkits changes around persistence may of actually made it
worse than vanilla.

This should fully solve all of the issues around it so that only natural
influences natural spawns.

diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index 5589ee42959e3665dd5df9049fe108b6f6629608..e5365453655c0f394dea3d3b388afc24f7724b26 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -442,4 +442,15 @@ public class PaperWorldConfig {
     private void preventMovingIntoUnloadedChunks() {
         preventMovingIntoUnloadedChunks = getBoolean("prevent-moving-into-unloaded-chunks", false);
     }
+
+    public boolean countAllMobsForSpawning = false;
+    private void countAllMobsForSpawning() {
+        countAllMobsForSpawning = getBoolean("count-all-mobs-for-spawning", false);
+        if (countAllMobsForSpawning) {
+            log("Counting all mobs for spawning. Mob farms may reduce natural spawns elsewhere in world.");
+        } else {
+            log("Using improved mob spawn limits (Only Natural Spawns impact spawn limits for more natural spawns)");
+        }
+    }
 }
+
diff --git a/src/main/java/net/minecraft/world/level/NaturalSpawner.java b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
index 94d2d83da52ce20f12a4e3f235f75d5c537ae9d1..6f63f471c2c9a3b85c6fc92bdee31a5ff9714ff5 100644
--- a/src/main/java/net/minecraft/world/level/NaturalSpawner.java
+++ b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
@@ -85,6 +85,13 @@ public final class NaturalSpawner {
             MobCategory enumcreaturetype = entity.getType().getCategory();
 
             if (enumcreaturetype != MobCategory.MISC) {
+                // Paper start - Only count natural spawns
+                if (!entity.level.paperConfig.countAllMobsForSpawning &&
+                    !(entity.spawnReason == org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.NATURAL ||
+                        entity.spawnReason == org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.CHUNK_GEN)) {
+                    continue;
+                }
+                // Paper end
                 BlockPos blockposition = entity.blockPosition();
 
                 chunkSource.query(ChunkPos.asLong(blockposition), (chunk) -> {