Player#setInstance can now take an optional Position parameter

src/main/java/net/minestom/server/entity/Entity.java

@@ -1122,34 +1122,6 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer, P
         this.eyeHeight = eyeHeight;
     }
 
-    /**
-     * Gets if this entity is in the same chunk as the specified position.
-     *
-     * @param position the checked position chunk
-     * @return true if the entity is in the same chunk as {@code position}
-     */
-    public boolean sameChunk(@NotNull Position position) {
-        Check.notNull(position, "Position cannot be null");
-        final Position pos = getPosition();
-        final int chunkX1 = ChunkUtils.getChunkCoordinate((int) Math.floor(pos.getX()));
-        final int chunkZ1 = ChunkUtils.getChunkCoordinate((int) Math.floor(pos.getZ()));
-
-        final int chunkX2 = ChunkUtils.getChunkCoordinate((int) Math.floor(position.getX()));
-        final int chunkZ2 = ChunkUtils.getChunkCoordinate((int) Math.floor(position.getZ()));
-
-        return chunkX1 == chunkX2 && chunkZ1 == chunkZ2;
-    }
-
-    /**
-     * Gets if the entity is in the same chunk as another.
-     *
-     * @param entity the entity to check
-     * @return true if both entities are in the same chunk, false otherwise
-     */
-    public boolean sameChunk(@NotNull Entity entity) {
-        return sameChunk(entity.getPosition());
-    }
-
     /**
      * Removes the entity from the server immediately.
      * <p>

src/main/java/net/minestom/server/entity/EntityManager.java

@@ -66,6 +66,7 @@ public final class EntityManager {
 
             waitingPlayer.init();
 
+            // Spawn the player at Player#getRespawnPoint during the next instance tick
             spawningInstance.scheduleNextTick(waitingPlayer::setInstance);
         }
     }

src/main/java/net/minestom/server/entity/Player.java

@@ -683,22 +683,19 @@ public class Player extends LivingEntity implements CommandSender {
      * <p>
      * Be aware that because chunk operations are expensive,
      * it is possible for this method to be non-blocking when retrieving chunks is required.
-     * <p>
-     * When this method is called for the first time (during player login), the player will be teleport at {@link #getRespawnPoint()}.
      *
-     * @param instance the new instance of the player
+     * @param instance the new player instance
      */
-    @Override
+    public void setInstance(@NotNull Instance instance, @NotNull Position spawnPosition) {
-    public void setInstance(@NotNull Instance instance) {
         Check.notNull(instance, "instance cannot be null!");
         Check.argCondition(this.instance == instance, "Instance should be different than the current one");
 
-        final boolean firstSpawn = this.instance == null; // TODO: Handle player reconnections, must be false in that case too
-
         // true if the chunks need to be sent to the client, can be false if the instances share the same chunks (eg SharedInstance)
         final boolean needWorldRefresh = !InstanceUtils.areLinked(this.instance, instance);
 
         if (needWorldRefresh) {
+            final boolean firstSpawn = this.instance == null; // TODO: Handle player reconnections, must be false in that case too
+
             // Remove all previous viewable chunks (from the previous instance)
             for (Chunk viewableChunk : viewableChunks) {
                 viewableChunk.removeViewer(this);
@@ -712,13 +709,12 @@ public class Player extends LivingEntity implements CommandSender {
             }
 
             // Load all the required chunks
-            final Position pos = firstSpawn ? getRespawnPoint() : position;
+            final long[] visibleChunks = ChunkUtils.getChunksInRange(spawnPosition, getChunkRange());
-            final long[] visibleChunks = ChunkUtils.getChunksInRange(pos, getChunkRange());
 
             final ChunkCallback eachCallback = chunk -> {
                 if (chunk != null) {
-                    final int chunkX = ChunkUtils.getChunkCoordinate((int) pos.getX());
+                    final int chunkX = ChunkUtils.getChunkCoordinate((int) spawnPosition.getX());
-                    final int chunkZ = ChunkUtils.getChunkCoordinate((int) pos.getZ());
+                    final int chunkZ = ChunkUtils.getChunkCoordinate((int) spawnPosition.getZ());
                     if (chunk.getChunkX() == chunkX &&
                             chunk.getChunkZ() == chunkZ) {
                         updateViewPosition(chunkX, chunkZ);
@@ -728,7 +724,7 @@ public class Player extends LivingEntity implements CommandSender {
 
             final ChunkCallback endCallback = chunk -> {
                 // This is the last chunk to be loaded , spawn player
-                spawnPlayer(instance, firstSpawn);
+                spawnPlayer(instance, spawnPosition, firstSpawn);
             };
 
             // Chunk 0;0 always needs to be loaded
@@ -739,26 +735,40 @@ public class Player extends LivingEntity implements CommandSender {
         } else {
             // The player already has the good version of all the chunks.
             // We just need to refresh his entity viewing list and add him to the instance
-            spawnPlayer(instance, false);
+            spawnPlayer(instance, spawnPosition, false);
         }
     }
 
+    /**
+     * Changes the player instance without changing its position (defaulted to {@link #getRespawnPoint()}
+     * if the player is not in any instance.
+     *
+     * @param instance the new player instance
+     * @see #setInstance(Instance, Position)
+     */
+    @Override
+    public void setInstance(@NotNull Instance instance) {
+        setInstance(instance, this.instance != null ? getPosition() : getRespawnPoint());
+    }
+
     /**
      * Used to spawn the player once the client has all the required chunks.
      * <p>
      * Does add the player to {@code instance}, remove all viewable entities and call {@link PlayerSpawnEvent}.
      * <p>
-     * UNSAFE: only called with {@link #setInstance(Instance)}.
+     * UNSAFE: only called with {@link #setInstance(Instance, Position)}.
      *
+     * @param spawnPosition the position to teleport the player
      * @param firstSpawn    true if this is the player first spawn
      */
-    private void spawnPlayer(@NotNull Instance instance, boolean firstSpawn) {
+    private void spawnPlayer(@NotNull Instance instance, @Nullable Position spawnPosition, boolean firstSpawn) {
         this.viewableEntities.forEach(entity -> entity.removeViewer(this));
 
         super.setInstance(instance);
 
-        if (firstSpawn) {
+        if (spawnPosition != null && !position.isSimilar(spawnPosition)) {
-            teleport(getRespawnPoint());
+            teleport(spawnPosition,
+                    position.inSameChunk(spawnPosition) ? () -> refreshVisibleChunks(getChunk()) : null);
         } else {
             refreshVisibleChunks(getChunk());
         }
@@ -1519,7 +1529,7 @@ public class Player extends LivingEntity implements CommandSender {
         // New chunks indexes
         final long[] updatedVisibleChunks = ChunkUtils.getChunksInRange(newChunk.toPosition(), getChunkRange());
 
-        // Find the difference between the two arrays¬
+        // Find the difference between the two arrays
         final int[] oldChunks = ArrayUtils.getDifferencesBetweenArray(lastVisibleChunks, updatedVisibleChunks);
         final int[] newChunks = ArrayUtils.getDifferencesBetweenArray(updatedVisibleChunks, lastVisibleChunks);
 

src/main/java/net/minestom/server/utils/Position.java

@@ -1,5 +1,8 @@
 package net.minestom.server.utils;
 
+import net.minestom.server.utils.chunk.ChunkUtils;
+import org.jetbrains.annotations.NotNull;
+
 import java.util.Objects;
 
 /**
@@ -209,7 +212,7 @@ public class Position {
      * @param position the position to compare
      * @return true if the two positions are similar
      */
-    public boolean isSimilar(Position position) {
+    public boolean isSimilar(@NotNull Position position) {
         return Float.compare(position.x, x) == 0 &&
                 Float.compare(position.y, y) == 0 &&
                 Float.compare(position.z, z) == 0;
@@ -221,11 +224,27 @@ public class Position {
      * @param position the position to compare
      * @return true if the two positions have the same view
      */
-    public boolean hasSimilarView(Position position) {
+    public boolean hasSimilarView(@NotNull Position position) {
         return Float.compare(position.yaw, yaw) == 0 &&
                 Float.compare(position.pitch, pitch) == 0;
     }
 
+    /**
+     * Gets if two positions are in the same chunk.
+     *
+     * @param position the checked position chunk
+     * @return true if 'this' is in the same chunk as {@code position}
+     */
+    public boolean inSameChunk(@NotNull Position position) {
+        final int chunkX1 = ChunkUtils.getChunkCoordinate((int) Math.floor(getX()));
+        final int chunkZ1 = ChunkUtils.getChunkCoordinate((int) Math.floor(getZ()));
+
+        final int chunkX2 = ChunkUtils.getChunkCoordinate((int) Math.floor(position.getX()));
+        final int chunkZ2 = ChunkUtils.getChunkCoordinate((int) Math.floor(position.getZ()));
+
+        return chunkX1 == chunkX2 && chunkZ1 == chunkZ2;
+    }
+
     @Override
     public int hashCode() {
         return Objects.hash(x, y, z, yaw, pitch);