From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: William Blake Galbreath <blake.galbreath@gmail.com>
Date: Sat, 6 Jul 2019 17:00:04 -0500
Subject: [PATCH] Dont send useless entity packets

Original code by PurpurMC, licensed under MIT
You can find the original code on https://github.com/PurpurMC/Purpur

diff --git a/src/main/java/net/minecraft/server/level/ServerEntity.java b/src/main/java/net/minecraft/server/level/ServerEntity.java
index f4569f8e53fc22a8a580fcaebbe773b497c11304..104b4f9165f417c4f71aa526e918c8e47f1c905d 100644
--- a/src/main/java/net/minecraft/server/level/ServerEntity.java
+++ b/src/main/java/net/minecraft/server/level/ServerEntity.java
@@ -181,6 +181,7 @@ public class ServerEntity {
                         this.teleportDelay = 0;
                         packet1 = new ClientboundTeleportEntityPacket(this.entity);
                     }
+                    if (wtf.etil.mirai.MiraiConfig.dontSendUselessEntityPackets && isUselessPacket(packet1)) packet1 = null; // Purpur
                 }
 
                 if ((this.trackDelta || this.entity.hasImpulse || this.entity instanceof LivingEntity && ((LivingEntity) this.entity).isFallFlying()) && this.tickCount > 0) {
@@ -247,6 +248,22 @@ public class ServerEntity {
 
     }
 
+    // Purpur start
+    private boolean isUselessPacket(Packet<?> possibleUselessPacket) {
+        if (possibleUselessPacket instanceof ClientboundMoveEntityPacket) {
+            ClientboundMoveEntityPacket packet = (ClientboundMoveEntityPacket) possibleUselessPacket;
+            if (possibleUselessPacket instanceof ClientboundMoveEntityPacket.Pos) {
+                return packet.getXa() == 0 && packet.getYa() == 0 && packet.getZa() == 0;
+            } else if (possibleUselessPacket instanceof ClientboundMoveEntityPacket.PosRot) {
+                return packet.getXa() == 0 && packet.getYa() == 0 && packet.getZa() == 0 && packet.getyRot() == 0 && packet.getxRot() == 0;
+            } else if (possibleUselessPacket instanceof ClientboundMoveEntityPacket.Rot) {
+                return packet.getyRot() == 0 && packet.getxRot() == 0;
+            }
+        }
+        return false;
+    }
+    // Purpur end
+
     public void removePairing(ServerPlayer player) {
         this.entity.stopSeenByPlayer(player);
         // Pufferfish start - ensure main thread
diff --git a/src/main/java/wtf/etil/mirai/MiraiConfig.java b/src/main/java/wtf/etil/mirai/MiraiConfig.java
index 7ff2d1e0124757401b4e70158bbe5ada18614aa3..15121a29de7a5b6b6ae062449221ad586ead655e 100644
--- a/src/main/java/wtf/etil/mirai/MiraiConfig.java
+++ b/src/main/java/wtf/etil/mirai/MiraiConfig.java
@@ -153,4 +153,10 @@ public class MiraiConfig {
                                 "Whether or not vanilla anticheat should check for passengers flying.");
     }
 
+    public static boolean dontSendUselessEntityPackets;
+    private static void uselessEntityPackets() {
+        dontSendUselessEntityPackets = getBoolean("dont-send-useless-entity-packets", true,
+                                        "Whether or not server should send entity packets with null movements.");
+    }
+
 }
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