From af430ebc3f1a87c1a08e90e73fc15040c61cee00 Mon Sep 17 00:00:00 2001
From: Felix Cravic <themode@outlook.fr>
Date: Wed, 27 May 2020 22:06:22 +0200
Subject: [PATCH] Entity#getPosition is now fully synchronized with the entity
 position

---
 src/main/java/fr/themode/demo/MainDemo.java   | 71 +++++++++++++++++++
 .../demo/generator/ChunkGeneratorDemo.java    |  2 +-
 .../net/minestom/server/entity/Entity.java    | 10 +++
 3 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/fr/themode/demo/MainDemo.java

diff --git a/src/main/java/fr/themode/demo/MainDemo.java b/src/main/java/fr/themode/demo/MainDemo.java
new file mode 100644
index 000000000..08c86e761
--- /dev/null
+++ b/src/main/java/fr/themode/demo/MainDemo.java
@@ -0,0 +1,71 @@
+package fr.themode.demo;
+
+import net.minestom.server.MinecraftServer;
+import net.minestom.server.event.player.PlayerLoginEvent;
+import net.minestom.server.event.player.PlayerSpawnEvent;
+import net.minestom.server.instance.*;
+import net.minestom.server.instance.batch.ChunkBatch;
+import net.minestom.server.instance.block.Block;
+import net.minestom.server.network.ConnectionManager;
+import net.minestom.server.utils.Position;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class MainDemo {
+
+    public static void main(String[] args) {
+        // Initialization
+        MinecraftServer minecraftServer = MinecraftServer.init();
+
+        InstanceManager instanceManager = MinecraftServer.getInstanceManager();
+        // Create the instance
+        InstanceContainer instanceContainer = instanceManager.createInstanceContainer();
+        // Set the ChunkGenerator
+        instanceContainer.setChunkGenerator(new GeneratorDemo());
+        // Enable the auto chunk loading (when players come close)
+        instanceContainer.enableAutoChunkLoad(true);
+
+        // Add event listeners
+        ConnectionManager connectionManager = MinecraftServer.getConnectionManager();
+        connectionManager.addPlayerInitialization(player -> {
+            // Set the spawning instance
+            player.addEventCallback(PlayerLoginEvent.class, event -> {
+                event.setSpawningInstance(instanceContainer);
+            });
+
+            // Teleport the player at spawn
+            player.addEventCallback(PlayerSpawnEvent.class, event -> {
+                player.teleport(new Position(0, 45, 0));
+            });
+        });
+
+        // Start the server
+        minecraftServer.start("localhost", 55555);
+    }
+
+    private static class GeneratorDemo extends ChunkGenerator {
+
+        @Override
+        public void generateChunkData(ChunkBatch batch, int chunkX, int chunkZ) {
+            // Set chunk blocks
+            for (byte x = 0; x < Chunk.CHUNK_SIZE_X; x++)
+                for (byte z = 0; z < Chunk.CHUNK_SIZE_Z; z++) {
+                    for (byte y = 0; y < 40; y++) {
+                        batch.setBlock(x, y, z, Block.STONE);
+                    }
+                }
+        }
+
+        @Override
+        public void fillBiomes(Biome[] biomes, int chunkX, int chunkZ) {
+            Arrays.fill(biomes, Biome.PLAINS);
+        }
+
+        @Override
+        public List<ChunkPopulator> getPopulators() {
+            return null;
+        }
+    }
+
+}
diff --git a/src/main/java/fr/themode/demo/generator/ChunkGeneratorDemo.java b/src/main/java/fr/themode/demo/generator/ChunkGeneratorDemo.java
index 6a2d064c8..4beae2907 100644
--- a/src/main/java/fr/themode/demo/generator/ChunkGeneratorDemo.java
+++ b/src/main/java/fr/themode/demo/generator/ChunkGeneratorDemo.java
@@ -16,7 +16,7 @@ public class ChunkGeneratorDemo extends ChunkGenerator {
     public void generateChunkData(ChunkBatch batch, int chunkX, int chunkZ) {
         for (byte x = 0; x < Chunk.CHUNK_SIZE_X; x++)
             for (byte z = 0; z < Chunk.CHUNK_SIZE_Z; z++) {
-                for (byte y = 0; y < 65; y++) {
+                for (byte y = 0; y < 40; y++) {
                     batch.setBlock(x, y, z, Block.STONE);
                 }
             }
diff --git a/src/main/java/net/minestom/server/entity/Entity.java b/src/main/java/net/minestom/server/entity/Entity.java
index 12c9e9c61..f02acddcc 100644
--- a/src/main/java/net/minestom/server/entity/Entity.java
+++ b/src/main/java/net/minestom/server/entity/Entity.java
@@ -55,6 +55,7 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
     protected Instance instance;
     protected Position position;
     protected float lastX, lastY, lastZ;
+    protected float cacheX, cacheY, cacheZ; // Used to synchronize with #getPosition
     protected float lastYaw, lastPitch;
     private int id;
 
@@ -286,6 +287,12 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
             return;
         }
 
+        if (cacheX != position.getX() ||
+                cacheY != position.getY() ||
+                cacheZ != position.getZ()) {
+            teleport(position);
+        }
+
         if (shouldUpdate(time)) {
             this.lastUpdate = time;
 
@@ -689,6 +696,9 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
         position.setX(x);
         position.setY(y);
         position.setZ(z);
+        this.cacheX = x;
+        this.cacheY = y;
+        this.cacheZ = z;
 
         if (hasPassenger()) {
             for (Entity passenger : getPassengers()) {