From c51e1da52848ab61068b678c97edcd3e8f0c5479 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 14 Jan 2018 17:36:02 -0500
Subject: [PATCH] PlayerNaturallySpawnCreaturesEvent

This event can be used for when you want to exclude a certain player
from triggering monster spawns on a server.

Also a highly more effecient way to blanket block spawns in a world

diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
index f2b024857..ed9e2e3e1 100644
--- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
+++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
@@ -693,12 +693,17 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
         int chunkRange = world.spigotConfig.mobSpawnRange;
         chunkRange = (chunkRange > world.spigotConfig.viewDistance) ? (byte) world.spigotConfig.viewDistance : chunkRange;
         chunkRange = (chunkRange > 8) ? 8 : chunkRange;
-
-        double blockRange = Math.pow(chunkRange << 4, 2);
+        final int finalChunkRange = chunkRange; // Paper for lambda below
+        //double blockRange = Math.pow(chunkRange << 4, 2); // Paper - use the range from the event
         // Spigot end
 
         return this.playerMap.a(chunkcoordintpair.pair()).noneMatch((entityplayer) -> {
-            return !entityplayer.isSpectator() && a(chunkcoordintpair, (Entity) entityplayer) < blockRange; // Spigot
+            // Paper start -
+            com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent event
+                = new com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent(entityplayer.getBukkitEntity(), (byte)finalChunkRange);
+            final double blockRange = (double)((event.getSpawnRadius() << 4) * (event.getSpawnRadius() << 4));
+            return event.isCancelled() || (!entityplayer.isSpectator() && a(chunkcoordintpair, (Entity) entityplayer) < blockRange); // Spigot
+            // Paper end
         });
     }
 
-- 
2.21.0