Paper/patches/server/0400-Reduce-allocation-of-Vec3D-by-entity-tracker.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
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/network/protocol/game/VecDeltaCodec.java b/src/main/java/net/minecraft/network/protocol/game/VecDeltaCodec.java
index 05ac41e136da43284fb24a6b698ebd36318278fb..5ca3ad7b3d7606accd0a58b3c708fadb349608f7 100644
--- a/src/main/java/net/minecraft/network/protocol/game/VecDeltaCodec.java
+++ b/src/main/java/net/minecraft/network/protocol/game/VecDeltaCodec.java
@@ -5,7 +5,7 @@ import org.jetbrains.annotations.VisibleForTesting;
 
 public class VecDeltaCodec {
     private static final double TRUNCATION_STEPS = 4096.0D;
-    private Vec3 base = Vec3.ZERO;
+    public Vec3 base = Vec3.ZERO; // Paper
 
     @VisibleForTesting
     static long encode(double value) {
diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index 487ea2ecb0ea82e001731fa0458aff1ac9d3c0dc..8d8bb430e44d7608a8aa44c7feb41797b8bbfb06 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -1343,9 +1343,14 @@ 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) {
+                // 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
                 Vec3 vec3d = player.position().subtract(this.entity.position());
                 double d0 = (double) Math.min(this.getEffectiveRange(), io.papermc.paper.chunk.system.ChunkSystem.getSendViewDistance(player) * 16); // Paper - per player view distance
-                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);
 
diff --git a/src/main/java/net/minecraft/server/level/ServerEntity.java b/src/main/java/net/minecraft/server/level/ServerEntity.java
index 5ec480397fb043717c63961651f7c62440e57201..3f3c7ced3a43e2b0eb451930c09188e3706a1bee 100644
--- a/src/main/java/net/minecraft/server/level/ServerEntity.java
+++ b/src/main/java/net/minecraft/server/level/ServerEntity.java
@@ -161,7 +161,13 @@ public class ServerEntity {
                 i = Mth.floor(this.entity.getYRot() * 256.0F / 360.0F);
                 j = Mth.floor(this.entity.getXRot() * 256.0F / 360.0F);
                 Vec3 vec3d = this.entity.trackingPosition();
-                boolean flag1 = this.positionCodec.delta(vec3d).lengthSqr() >= 7.62939453125E-6D;
+                // Paper start - reduce allocation of Vec3D here
+                Vec3 base = this.positionCodec.base;
+                double vec3d_dx = vec3d.x - base.x;
+                double vec3d_dy = vec3d.y - base.y;
+                double vec3d_dz = vec3d.z - base.z;
+                boolean flag1 = (vec3d_dx * vec3d_dx + vec3d_dy * vec3d_dy + vec3d_dz * vec3d_dz) >= 7.62939453125E-6D;
+                // Paper end - reduce allocation of Vec3D here
                 Packet<?> packet1 = null;
                 boolean flag2 = flag1 || this.tickCount % 60 == 0;
                 boolean flag3 = Math.abs(i - this.yRotp) >= 1 || Math.abs(j - this.xRotp) >= 1;