Paper/patches/server/0421-Reduce-allocation-of-Vec3D-by-entity-tracker.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <spottedleaf@spottedleaf.dev>
Date: Mon, 27 Apr 2020 00:04:16 -0700
Subject: [PATCH] Reduce allocation of Vec3D by entity tracker


diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index ac846039c98ed297dcb913ef4a02d4ab259debd2..eaee840359e13914865433a78e683ce3c4196956 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -1928,9 +1928,13 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
         public void updatePlayer(ServerPlayer player) {
             org.spigotmc.AsyncCatcher.catchOp("player tracker update"); // Spigot
             if (player != this.entity) {
-                Vec3 vec3d = player.position().subtract(this.entity.position());
+                // Paper start - remove allocation of Vec3D here
+                // Vec3 vec3d = player.position().subtract(this.entity.position());
+                double vec3d_dx = player.getX() - this.entity.getX();
+                double vec3d_dz = player.getZ() - this.entity.getZ();
+                // Paper end - remove allocation of Vec3D here
                 double d0 = (double) Math.min(this.getEffectiveRange(), (ChunkMap.this.viewDistance - 1) * 16);
-                double d1 = vec3d.x * vec3d.x + vec3d.z * vec3d.z;
+                double d1 = vec3d_dx * vec3d_dx + vec3d_dz * vec3d_dz; // Paper
                 double d2 = d0 * d0;
                 boolean flag = d1 <= d2 && this.entity.broadcastToPlayer(player);