From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jedediah Smith <jedediah@silencegreys.com>
Date: Wed, 2 Mar 2016 23:13:07 -0600
Subject: [PATCH] Send absolute position the first time an entity is seen


diff --git a/src/main/java/net/minecraft/server/level/EntityTrackerEntry.java b/src/main/java/net/minecraft/server/level/EntityTrackerEntry.java
index 9ad74b380a92e3a563e1a891e81401d8b4707bcf..beb0beb716869978be6bc5a78ce3b6cf785c5aee 100644
--- a/src/main/java/net/minecraft/server/level/EntityTrackerEntry.java
+++ b/src/main/java/net/minecraft/server/level/EntityTrackerEntry.java
@@ -4,6 +4,7 @@ import com.google.common.collect.Lists;
 import com.mojang.datafixers.util.Pair;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
@@ -52,7 +53,7 @@ public class EntityTrackerEntry {
     private final Entity tracker;
     private final int d;
     private final boolean e;
-    private final Consumer<Packet<?>> f;
+    private final Consumer<Packet<?>> f; private Consumer<Packet<?>> getPacketConsumer() { return f; } // Paper - OBFHELPER
     private long xLoc;
     private long yLoc;
     private long zLoc;
@@ -67,8 +68,23 @@ public class EntityTrackerEntry {
     private boolean r;
     // CraftBukkit start
     private final Set<EntityPlayer> trackedPlayers;
+    // Paper start
+    private java.util.Map<EntityPlayer, Boolean> trackedPlayerMap = null;
+
+    /**
+     * Requested in https://github.com/PaperMC/Paper/issues/1537 to allow intercepting packets
+     */
+    public void sendPlayerPacket(EntityPlayer player, Packet packet) {
+        player.playerConnection.sendPacket(packet);
+    }
+
+    public EntityTrackerEntry(WorldServer worldserver, Entity entity, int i, boolean flag, Consumer<Packet<?>> consumer, java.util.Map<EntityPlayer, Boolean> trackedPlayers) {
+        this(worldserver, entity, i, flag, consumer, trackedPlayers.keySet());
+        trackedPlayerMap = trackedPlayers;
+    }
 
     public EntityTrackerEntry(WorldServer worldserver, Entity entity, int i, boolean flag, Consumer<Packet<?>> consumer, Set<EntityPlayer> trackedPlayers) {
+        // Paper end
         this.trackedPlayers = trackedPlayers;
         // CraftBukkit end
         this.m = Vec3D.ORIGIN;
@@ -189,7 +205,25 @@ public class EntityTrackerEntry {
                 }
 
                 if (packet1 != null) {
-                    this.f.accept(packet1);
+                    // paper start
+                    if (trackedPlayerMap == null || packet1 instanceof PacketPlayOutEntityTeleport) {
+                        this.f.accept((packet1));
+                    } else {
+                        PacketPlayOutEntityTeleport teleportPacket = null;
+
+                        for (java.util.Map.Entry<EntityPlayer, Boolean> viewer : trackedPlayerMap.entrySet()) {
+                            if (viewer.getValue()) {
+                                viewer.setValue(false);
+                                if (teleportPacket == null) {
+                                    teleportPacket = new PacketPlayOutEntityTeleport(this.tracker);
+                                }
+                                sendPlayerPacket(viewer.getKey(), teleportPacket);
+                            } else {
+                                sendPlayerPacket(viewer.getKey(), packet1);
+                            }
+                        }
+                    }
+                    // Paper end
                 }
 
                 this.c();
diff --git a/src/main/java/net/minecraft/server/level/PlayerChunkMap.java b/src/main/java/net/minecraft/server/level/PlayerChunkMap.java
index 62245fa420390dc0a70ba9a95505dc46cd8aa64a..788a45d5426f0752509442aec2d28b1f32f63cb1 100644
--- a/src/main/java/net/minecraft/server/level/PlayerChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/PlayerChunkMap.java
@@ -1303,10 +1303,14 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
         private final Entity tracker;
         private final int trackingDistance;
         private SectionPosition e;
-        public final Set<EntityPlayer> trackedPlayers = Sets.newHashSet();
+        // Paper start
+        // Replace trackedPlayers Set with a Map. The value is true until the player receives
+        // their first update (which is forced to have absolute coordinates), false afterward.
+        public java.util.Map<EntityPlayer, Boolean> trackedPlayerMap = new java.util.HashMap<>();
+        public Set<EntityPlayer> trackedPlayers = trackedPlayerMap.keySet();
 
         public EntityTracker(Entity entity, int i, int j, boolean flag) {
-            this.trackerEntry = new EntityTrackerEntry(PlayerChunkMap.this.world, entity, j, flag, this::broadcast, trackedPlayers); // CraftBukkit
+            this.trackerEntry = new EntityTrackerEntry(PlayerChunkMap.this.world, entity, j, flag, this::broadcast, trackedPlayerMap); // CraftBukkit // Paper
             this.tracker = entity;
             this.trackingDistance = i;
             this.e = SectionPosition.a(entity);
@@ -1388,7 +1392,7 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
                     entityplayer.removeQueue.remove(Integer.valueOf(this.tracker.getId()));
                     // CraftBukkit end
 
-                    if (flag1 && this.trackedPlayers.add(entityplayer)) {
+                    if (flag1 && this.trackedPlayerMap.putIfAbsent(entityplayer, true) == null) { // Paper
                         this.trackerEntry.b(entityplayer);
                     }
                 } else if (this.trackedPlayers.remove(entityplayer)) {