Paper/patches/server/0925-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 a043ac10834562d357ef0b5aded2e916e2a0d056..74276c368016fcc4dbf9579b2ecbadc9614baf15 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 = 4096.0;
-    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 6c667823c2ef15766f3afc1a9c819cb6c24b0912..4c1cf5798209297e1e8a634b63770e917a84a63c 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -1519,10 +1519,14 @@ 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) {
-                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
                 int i = ChunkMap.this.getPlayerViewDistance(player);
                 double d0 = (double) Math.min(this.getEffectiveRange(), i * 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;
                 // Paper start - Configurable entity tracking range by Y
                 boolean flag = d1 <= d2;
diff --git a/src/main/java/net/minecraft/server/level/ServerEntity.java b/src/main/java/net/minecraft/server/level/ServerEntity.java
index a2fbbbd7a66d4e7b1063638f8467e8887a417282..0e7ace92522fbd4cef7b2c2b8a0f8b86c2cce192 100644
--- a/src/main/java/net/minecraft/server/level/ServerEntity.java
+++ b/src/main/java/net/minecraft/server/level/ServerEntity.java
@@ -163,7 +163,13 @@ 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.lastSentYRot) >= 1 || Math.abs(j - this.lastSentXRot) >= 1;