Correct Instance#getNearbyEntities implementation

src/main/java/net/minestom/server/instance/Instance.java

@@ -495,13 +495,27 @@ public abstract class Instance implements BlockGetter, BlockSetter, Tickable, Ta
         int maxX = ChunkUtils.getChunkCoordinate(point.x() + range);
         int minZ = ChunkUtils.getChunkCoordinate(point.z() - range);
         int maxZ = ChunkUtils.getChunkCoordinate(point.z() + range);
+
+        // Cache squared range to prevent sqrt operations
+        double squaredRange = range * range;
+
         List<Entity> result = new ArrayList<>();
         synchronized (entitiesLock) {
             for (int x = minX; x <= maxX; ++x) {
                 for (int z = minZ; z <= maxZ; ++z) {
                     Chunk chunk = getChunk(x, z);
-                    if (chunk != null) {
-                        result.addAll(getChunkEntities(chunk));
+
+                    if (chunk == null) {
+                        continue;
+                    }
+
+                    Set<Entity> chunkEntities = getChunkEntities(chunk);
+
+                    // Filter all entities out of range
+                    for (Entity chunkEntity : chunkEntities) {
+                        if (point.distanceSquared(chunkEntity.getPosition()) < squaredRange) {
+                            result.add(chunkEntity);
+                        }
                     }
                 }
             }

src/test/java/demo/Main.java

@@ -39,6 +39,7 @@ public class Main {
         commandManager.register(new ShutdownCommand());
         commandManager.register(new TeleportCommand());
         commandManager.register(new PlayersCommand());
+        commandManager.register(new FindCommand());
         commandManager.register(new PotionCommand());
         commandManager.register(new TitleCommand());
         commandManager.register(new BookCommand());
@@ -50,6 +51,7 @@ public class Main {
         commandManager.register(new GiveCommand());
         commandManager.register(new SetBlockCommand());
 
+
         commandManager.setUnknownCommandCallback((sender, command) -> sender.sendMessage(Component.text("Unknown command", NamedTextColor.RED)));
 
         MinecraftServer.getBenchmarkManager().enable(Duration.of(10, TimeUnit.SECOND));

src/test/java/demo/commands/FindCommand.java

@@ -0,0 +1,41 @@
+package demo.commands;
+
+import net.minestom.server.command.CommandSender;
+import net.minestom.server.command.builder.Command;
+import net.minestom.server.command.builder.CommandContext;
+import net.minestom.server.entity.Entity;
+import net.minestom.server.entity.Player;
+
+import java.util.Collection;
+
+import static net.minestom.server.command.builder.arguments.ArgumentType.*;
+
+public class FindCommand extends Command {
+    public FindCommand() {
+        super("find");
+
+        this.addSyntax(
+                this::executorEntity,
+                Literal("entity"),
+                Float("range")
+        );
+    }
+
+    private void executorEntity(CommandSender sender, CommandContext context) {
+        Player player = sender.asPlayer();
+        float range = context.get("range");
+
+        Collection<Entity> entities = player.getInstance().getNearbyEntities(player.getPosition(), range);
+
+        player.sendMessage("Search result: ");
+
+        for (Entity entity : entities) {
+            player.sendMessage("    " + entity.getEntityType() + ": ");
+            player.sendMessage("        Meta: " + entity.getEntityMeta());
+            player.sendMessage("        Permissions: " + entity.getAllPermissions());
+            player.sendMessage("        Position: " + entity.getPosition());
+        }
+
+        player.sendMessage("End result.");
+    }
+}