From d9d785e3118eb7f30611eca9330f0c5aab6ae80e Mon Sep 17 00:00:00 2001
From: Zach Brown <zach.brown@destroystokyo.com>
Date: Sun, 22 May 2016 20:20:55 -0500
Subject: [PATCH] Optional TNT doesn't move in water


diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index 805aa5699..92ab55182 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -2,7 +2,6 @@ package com.destroystokyo.paper;
 
 import java.util.List;
 
-import org.bukkit.Bukkit;
 import org.bukkit.configuration.file.YamlConfiguration;
 import org.spigotmc.SpigotWorldConfig;
 
@@ -287,4 +286,14 @@ public class PaperWorldConfig {
             );
         }
     }
+
+    public boolean preventTntFromMovingInWater;
+    private void preventTntFromMovingInWater() {
+        if (PaperConfig.version < 13) {
+            boolean oldVal = getBoolean("enable-old-tnt-cannon-behaviors", false);
+            set("prevent-tnt-from-moving-in-water", oldVal);
+        }
+        preventTntFromMovingInWater = getBoolean("prevent-tnt-from-moving-in-water", false);
+        log("Prevent TNT from moving in water: " + preventTntFromMovingInWater);
+    }
 }
diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
index 3dcd93e5e..b68e2fc04 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -1094,6 +1094,12 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     }
 
     public boolean au() {
+        // Paper start
+        return this.doWaterMovement();
+    }
+
+    public boolean doWaterMovement() {
+        // Paper end
         return this.isInWater() || this.l();
     }
 
@@ -2620,6 +2626,12 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     }
 
     public boolean bD() {
+        // Paper start
+        return this.pushedByWater();
+    }
+
+    public boolean pushedByWater() {
+        // Paper end
         return true;
     }
 
diff --git a/src/main/java/net/minecraft/server/EntityTNTPrimed.java b/src/main/java/net/minecraft/server/EntityTNTPrimed.java
index e0535604b..91e332c3a 100644
--- a/src/main/java/net/minecraft/server/EntityTNTPrimed.java
+++ b/src/main/java/net/minecraft/server/EntityTNTPrimed.java
@@ -149,4 +149,49 @@ public class EntityTNTPrimed extends Entity {
     public Packet<?> N() {
         return new PacketPlayOutSpawnEntity(this);
     }
+
+    // Paper start - Optional prevent TNT from moving in water
+    @Override
+    public boolean pushedByWater() {
+        return !world.paperConfig.preventTntFromMovingInWater && super.pushedByWater();
+    }
+
+    /**
+     * Author: Jedediah Smith <jedediah@silencegreys.com>
+     */
+    @Override
+    public boolean doWaterMovement() {
+        if (!world.paperConfig.preventTntFromMovingInWater) return super.doWaterMovement();
+
+        // Preserve velocity while calling the super method
+        double oldMotX = this.motX;
+        double oldMotY = this.motY;
+        double oldMotZ = this.motZ;
+
+        super.doWaterMovement();
+
+        this.motX = oldMotX;
+        this.motY = oldMotY;
+        this.motZ = oldMotZ;
+
+        if (this.inWater) {
+            // Send position and velocity updates to nearby players on every tick while the TNT is in water.
+            // This does pretty well at keeping their clients in sync with the server.
+            EntityTrackerEntry ete = ((WorldServer) this.getWorld()).getTracker().trackedEntities.get(this.getId());
+            if (ete != null) {
+                PacketPlayOutEntityVelocity velocityPacket = new PacketPlayOutEntityVelocity(this);
+                PacketPlayOutEntityTeleport positionPacket = new PacketPlayOutEntityTeleport(this);
+
+                ete.trackedPlayers.stream()
+                        .filter(viewer -> (viewer.locX - this.locX) * (viewer.locY - this.locY) * (viewer.locZ - this.locZ) < 16 * 16)
+                        .forEach(viewer -> {
+                    viewer.playerConnection.sendPacket(velocityPacket);
+                    viewer.playerConnection.sendPacket(positionPacket);
+                });
+            }
+        }
+
+        return this.inWater;
+    }
+    // Paper end
 }
-- 
2.21.0