0019-Smooth-teleportation.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: hpfxd <me@hpfxd.com>
Date: Sun, 31 Oct 2021 05:30:25 -0400
Subject: [PATCH] Smooth teleportation

When teleporting, if the player's yaw & pitch are the same, the server
will send a relative teleport packet indicating that the player's
rotation should stay the same as it currently is on the client.

diff --git a/src/main/java/com/hpfxd/pandaspigot/config/PandaSpigotWorldConfig.java b/src/main/java/com/hpfxd/pandaspigot/config/PandaSpigotWorldConfig.java
index b5f16e8cab9e43ad7597b2ea5bc921399b37872b..bde014f003bccca916dbc74fc27436bf4b193fdf 100644
--- a/src/main/java/com/hpfxd/pandaspigot/config/PandaSpigotWorldConfig.java
+++ b/src/main/java/com/hpfxd/pandaspigot/config/PandaSpigotWorldConfig.java
@@ -13,6 +13,15 @@ public class PandaSpigotWorldConfig {
             "higher, unless you're constantly changing the time, or the server is lagging.")
     public int timeUpdateFrequency = 100;
     
+    @Comment("This option makes it so that when players are teleported to a location\n" +
+            "with the same rotation they currently have, the server will send a special\n" +
+            "packet indicating that the client should not update it's rotation at all.\n" +
+            "\n" +
+            "For example, normally constantly teleporting a player to their own location\n" +
+            "will make moving their head very difficult, especially for players with higher latency.\n" +
+            "With this option enabled, they will be able to move their head just like normal.")
+    public boolean smoothTeleportation = false;
+    
     @Comment("These options control velocity players receive when damaged.")
     public KnockbackConfig knockback;
     
diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
index 4391ad7e7cf547b5e179c06e64b3a6e02cbe7a41..5842cedc81b90b4f3565d71ba5dfa8c0c98dfca6 100644
--- a/src/main/java/net/minecraft/server/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/PlayerConnection.java
@@ -68,6 +68,13 @@ import org.github.paperspigot.PaperSpigotConfig; // PaperSpigot
 public class PlayerConnection implements PacketListenerPlayIn, IUpdatePlayerListBox {
 
     private static final Logger c = LogManager.getLogger();
+    // PandaSpigot start - Smooth teleportation
+    private static final Set<PacketPlayOutPosition.EnumPlayerTeleportFlags> TELEPORT_NO_ROT =
+            com.google.common.collect.Sets.immutableEnumSet(
+                    PacketPlayOutPosition.EnumPlayerTeleportFlags.X_ROT,
+                    PacketPlayOutPosition.EnumPlayerTeleportFlags.Y_ROT
+            );
+    // PandaSpigot end
     public final NetworkManager networkManager;
     private final MinecraftServer minecraftServer;
     public EntityPlayer player;
@@ -274,7 +281,13 @@ public class PlayerConnection implements PacketListenerPlayIn, IUpdatePlayerList
 
                         // If the event is cancelled we move the player back to their old location.
                         if (event.isCancelled()) {
+                            // PandaSpigot start - Smooth teleportation
+                            if (this.player.world.pandaSpigotConfig.smoothTeleportation) {
+                                this.player.playerConnection.sendPacket(new PacketPlayOutPosition(from.getX(), from.getY(), from.getZ(), 0, 0, TELEPORT_NO_ROT));
+                            } else {
+                            // PandaSpigot end
                             this.player.playerConnection.sendPacket(new PacketPlayOutPosition(from.getX(), from.getY(), from.getZ(), from.getYaw(), from.getPitch(), Collections.<PacketPlayOutPosition.EnumPlayerTeleportFlags>emptySet()));
+                            } // PandaSpigot - closing bracket
                             return;
                         }
 
@@ -518,6 +531,16 @@ public class PlayerConnection implements PacketListenerPlayIn, IUpdatePlayerList
     }
 
     private void internalTeleport(double d0, double d1, double d2, float f, float f1, Set set) {
+        // PandaSpigot start - Smooth teleportation
+        if (this.player.world.pandaSpigotConfig.smoothTeleportation && set.isEmpty()) {
+            // if yaw & pitch are same, send a relative teleport
+            if (this.player.yaw == f && this.player.pitch == f1) {
+                set = TELEPORT_NO_ROT; // provided set is probably immutable
+                f = 0;
+                f1 = 0;
+            }
+        }
+        // PandaSpigot end
         if (Float.isNaN(f)) {
             f = 0;
         }