From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Tue, 25 Aug 2020 20:45:36 -0400
Subject: [PATCH] Fix Entity Teleportation and cancel velocity if teleported

Uses correct setPositionRotation for Entity teleporting instead of setLocation
as this is how Vanilla teleports entities.

Cancel any pending motion when teleported.

diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index ab6494f5a872bba5398bef0367b4d9257786f61e..ab45497e8f7720c9d60626b32e9c95779af676b0 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -691,7 +691,7 @@ public class ServerGamePacketListenerImpl implements ServerGamePacketListener {
     public void handleAcceptTeleportPacket(ServerboundAcceptTeleportationPacket packet) {
         PacketUtils.ensureRunningOnSameThread(packet, this, this.player.getLevel());
         if (packet.getId() == this.awaitingTeleport && this.awaitingPositionFromClient != null) { // CraftBukkit
-            this.player.absMoveTo(this.awaitingPositionFromClient.x, this.awaitingPositionFromClient.y, this.awaitingPositionFromClient.z, this.player.yRot, this.player.xRot);
+            this.player.moveTo(this.awaitingPositionFromClient.x, this.awaitingPositionFromClient.y, this.awaitingPositionFromClient.z, this.player.yRot, this.player.xRot); // Paper - use proper setPositionRotation for teleportation
             this.lastGoodX = this.awaitingPositionFromClient.x;
             this.lastGoodY = this.awaitingPositionFromClient.y;
             this.lastGoodZ = this.awaitingPositionFromClient.z;
@@ -1536,7 +1536,7 @@ public class ServerGamePacketListenerImpl implements ServerGamePacketListener {
         // CraftBukkit end
 
         this.awaitingTeleportTime = this.tickCount;
-        this.player.absMoveTo(d0, d1, d2, f, f1);
+        this.player.moveTo(d0, d1, d2, f, f1); // Paper - use proper setPositionRotation for teleportation
         this.player.forceCheckHighPriority(); // Paper
         this.player.connection.send(new ClientboundPlayerPositionPacket(d0 - d3, d1 - d4, d2 - d5, f - f2, f1 - f3, set, this.awaitingTeleport));
     }
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index aea2457510c75214bbb925307155611e981f115f..d69981a1b5a40418c7d17de5f3bece30592ae586 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -143,6 +143,7 @@ public abstract class Entity implements Nameable, CommandSource, net.minecraft.s
 
     // CraftBukkit start
     private static final int CURRENT_LEVEL = 2;
+    public boolean preserveMotion = true; // Paper - keep initial motion on first setPositionRotation
     static boolean isLevelAtLeast(CompoundTag tag, int level) {
         return tag.contains("Bukkit.updateLevel") && tag.getInt("Bukkit.updateLevel") >= level;
     }
@@ -1406,6 +1407,13 @@ public abstract class Entity implements Nameable, CommandSource, net.minecraft.s
     }
 
     public void moveTo(double x, double y, double z, float yaw, float pitch) {
+        // Paper - cancel entity velocity if teleported
+        if (!preserveMotion) {
+            this.deltaMovement = Vec3.ZERO;
+        } else {
+            this.preserveMotion = false;
+        }
+        // Paper end
         this.setPosAndOldPos(x, y, z);
         this.yRot = yaw;
         this.xRot = pitch;
diff --git a/src/main/java/net/minecraft/world/level/BaseSpawner.java b/src/main/java/net/minecraft/world/level/BaseSpawner.java
index 6ca378ec7868b855d46c749910c656f82ddb009f..091e72474ac199c38fff979a5faf524e011d8d0a 100644
--- a/src/main/java/net/minecraft/world/level/BaseSpawner.java
+++ b/src/main/java/net/minecraft/world/level/BaseSpawner.java
@@ -165,6 +165,7 @@ public abstract class BaseSpawner {
                                 return;
                             }
 
+                            entity.preserveMotion = true; // Paper - preserve entity motion from tag
                             entity.moveTo(entity.getX(), entity.getY(), entity.getZ(), world.random.nextFloat() * 360.0F, 0.0F);
                             if (entity instanceof Mob) {
                                 Mob entityinsentient = (Mob) entity;
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
index deeae62e9926f9435907c68e7d35e7420f5e79dd..1275768762884416fa3c68dab3a6671b24949976 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -556,7 +556,7 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
         }
 
         // entity.setLocation() throws no event, and so cannot be cancelled
-        entity.absMoveTo(location.getX(), location.getY(), location.getZ(), location.getYaw(), location.getPitch());
+        entity.moveTo(location.getX(), location.getY(), location.getZ(), location.getYaw(), location.getPitch()); // Paper - use proper setPosition, as per vanilla teleporting
         // SPIGOT-619: Force sync head rotation also
         entity.setYHeadRot(location.getYaw());
         ((net.minecraft.server.level.ServerLevel) entity.level).updateChunkPos(entity); // Spigot - register to new chunk