fix: center ground under chunks and align player spawn with chunk grid

scripts/game.gd

@@ -38,6 +38,7 @@ var _build_editor: InGameEditor = null
 
 
 var _stream_manager: ChunkStreamManager = null
+var _loaded_chunk_coords: Array[Vector3i] = []
 
 
 func _ready() -> void:
@@ -75,11 +76,75 @@ func _setup_chunk_streaming() -> void:
 	_stream_manager._load_chunk(Vector3i.ZERO)
 
 
-func _on_chunk_loaded(_coord: Vector3i, chunk_scene: Node) -> void:
+func _on_chunk_loaded(coord: Vector3i, chunk_scene: Node) -> void:
 	if chunk_scene is ChunkScene:
 		var cs := chunk_scene as ChunkScene
-		if not cs.world_objects.is_empty() or not cs.tile_layers.is_empty():
 		_hide_default_test_props()
+		if not (coord in _loaded_chunk_coords):
+			_loaded_chunk_coords.append(coord)
+		_adjust_ground_and_spawn_for_chunks(cs)
+
+
+func _adjust_ground_and_spawn_for_chunks(cs: ChunkScene) -> void:
+	var min_cx := 0
+	var max_cx := 0
+	var min_cy := 0
+	var max_cy := 0
+	for c in _loaded_chunk_coords:
+		min_cx = mini(min_cx, c.x)
+		max_cx = maxi(max_cx, c.x)
+		min_cy = mini(min_cy, c.y)
+		max_cy = maxi(max_cy, c.y)
+
+	var min_x := float(min_cx * Chunk.CHUNK_SIZE_X)
+	var max_x := float((max_cx + 1) * Chunk.CHUNK_SIZE_X)
+	var min_z := float(min_cy * Chunk.CHUNK_SIZE_Y)
+	var max_z := float((max_cy + 1) * Chunk.CHUNK_SIZE_Y)
+
+	var center_x := (min_x + max_x) * 0.5
+	var center_z := (min_z + max_z) * 0.5
+	var size_x := maxf(40.0, (max_x - min_x) + 8.0)
+	var size_z := maxf(40.0, (max_z - min_z) + 8.0)
+
+	var ground := get_node_or_null("Level/Ground") as StaticBody3D
+	if ground != null:
+		ground.position = Vector3(center_x, -0.5, center_z)
+		var shape_node := ground.find_child("CollisionShape3D", true, false) as CollisionShape3D
+		if shape_node != null:
+			var box: BoxShape3D
+			if shape_node.shape is BoxShape3D:
+				box = (shape_node.shape as BoxShape3D).duplicate() as BoxShape3D
+			else:
+				box = BoxShape3D.new()
+			box.size = Vector3(size_x, 1.0, size_z)
+			shape_node.shape = box
+		var mesh_node := ground.find_child("MeshInstance3D", true, false) as MeshInstance3D
+		if mesh_node != null:
+			var box_mesh: BoxMesh
+			if mesh_node.mesh is BoxMesh:
+				box_mesh = (mesh_node.mesh as BoxMesh).duplicate() as BoxMesh
+			else:
+				box_mesh = BoxMesh.new()
+			box_mesh.size = Vector3(size_x, 1.0, size_z)
+			mesh_node.mesh = box_mesh
+
+	var spawn_marker := get_node_or_null("Level/PlayerSpawn") as Node3D
+	var found_spawn: Variant = null
+	for obj in cs.world_objects:
+		if obj.type == "spawn_point" or (obj.properties is Dictionary and obj.properties.get("catalog_id") == "spawn_point"):
+			found_spawn = cs.global_position + Vector3(obj.position.x, 1.5, obj.position.y)
+			break
+
+	if found_spawn != null:
+		if spawn_marker != null:
+			spawn_marker.global_position = found_spawn
+		if not _aligned:
+			_player.global_position = found_spawn
+	elif spawn_marker != null and spawn_marker.global_position.is_equal_approx(Vector3(0, 1.5, 0)):
+		var default_center := Vector3(16.0, 1.5, 16.0)
+		spawn_marker.global_position = default_center
+		if not _aligned:
+			_player.global_position = default_center
 
 
 func _hide_default_test_props() -> void:
@@ -194,6 +259,7 @@ func _close_build_mode() -> void:
 	_player.set_process_unhandled_input(true)
 	_player._refresh_mouse_mode()
 
+	_loaded_chunk_coords.clear()
 	if _stream_manager == null:
 		_setup_chunk_streaming()
 	elif is_instance_valid(_stream_manager):
@@ -273,6 +339,7 @@ func _leave_world() -> void:
 
 ## Close the ENet connection and stop it from calling us back mid-teardown.
 func _teardown_net() -> void:
+	_loaded_chunk_coords.clear()
 	if _stream_manager != null and is_instance_valid(_stream_manager):
 		_stream_manager.clear_all_chunks()
 		_stream_manager.queue_free()

scripts/server.gd

@@ -213,6 +213,12 @@ func _try_load_real_content() -> Node:
 	marker.position = spawn_pos
 
 	var entries: Array = (index_result.data as Dictionary).get("chunks", [])
+	var min_cx := 0
+	var max_cx := 0
+	var min_cy := 0
+	var max_cy := 0
+	var found_spawn_obj: Variant = null
+
 	for entry in entries:
 		var cx: int = int(entry["cx"])
 		var cy: int = int(entry["cy"])
@@ -229,6 +235,61 @@ func _try_load_real_content() -> Node:
 		_build_chunk_collision(world_root, Vector3i(cx, cy, cz), decoded)
 		_chunks_loaded += 1
 
+		if _chunks_loaded == 1:
+			min_cx = cx
+			max_cx = cx
+			min_cy = cy
+			max_cy = cy
+		else:
+			min_cx = mini(min_cx, cx)
+			max_cx = maxi(max_cx, cx)
+			min_cy = mini(min_cy, cy)
+			max_cy = maxi(max_cy, cy)
+
+		if found_spawn_obj == null:
+			var chunk_origin := Vector3(
+				float(cx * Chunk.CHUNK_SIZE_X),
+				float(cz * Chunk.CHUNK_SIZE_Z),
+				float(cy * Chunk.CHUNK_SIZE_Y)
+			)
+			for obj in decoded.objects:
+				if obj.type == "spawn_point" or str(obj.properties.get("catalog_id", "")) == "spawn_point":
+					found_spawn_obj = chunk_origin + Vector3(obj.position.x, 1.5, obj.position.y)
+					break
+
+	if _chunks_loaded > 0:
+		var props := world_root.find_child("Props", true, false)
+		if props != null:
+			props.queue_free()
+		var chest := world_root.find_child("ScriptedChest", true, false)
+		if chest != null:
+			chest.queue_free()
+
+		var min_x := float(min_cx * Chunk.CHUNK_SIZE_X)
+		var max_x := float((max_cx + 1) * Chunk.CHUNK_SIZE_X)
+		var min_z := float(min_cy * Chunk.CHUNK_SIZE_Y)
+		var max_z := float((max_cy + 1) * Chunk.CHUNK_SIZE_Y)
+		var center_x := (min_x + max_x) * 0.5
+		var center_z := (min_z + max_z) * 0.5
+		var size_x := maxf(40.0, (max_x - min_x) + 8.0)
+		var size_z := maxf(40.0, (max_z - min_z) + 8.0)
+
+		var ground: StaticBody3D = world_root.find_child("Ground", true, false) as StaticBody3D
+		if ground != null:
+			ground.position = Vector3(center_x, -0.5, center_z)
+			var shape_node := ground.find_child("CollisionShape3D", true, false) as CollisionShape3D
+			if shape_node != null:
+				var box := BoxShape3D.new()
+				box.size = Vector3(size_x, 1.0, size_z)
+				shape_node.shape = box
+
+		if found_spawn_obj != null:
+			spawn_pos = found_spawn_obj
+		elif not (room.get("spawn") is Dictionary and (room.get("spawn") as Dictionary).has("pos")):
+			spawn_pos = Vector3(16.0, 1.5, 16.0)
+
+		marker.position = spawn_pos
+
 	return world_root
 
 

scripts/smoke_test_world_chunk_alignment.gd

@@ -0,0 +1,109 @@
+extends SceneTree
+## Regression test for world chunk alignment and ground positioning.
+
+var _passed: int = 0
+var _failed: int = 0
+
+
+func _check(label: String, condition: bool) -> void:
+	if condition:
+		print("  PASS: %s" % label)
+		_passed += 1
+	else:
+		printerr("  FAIL: %s" % label)
+		_failed += 1
+
+
+func _init() -> void:
+	call_deferred("_run_tests")
+
+
+func _run_tests() -> void:
+	print("--- World Chunk & Ground Alignment Test ---")
+	await process_frame
+
+	var packed: PackedScene = load("res://scenes/game.tscn")
+	var result := change_scene_to_packed(packed)
+	if result != OK:
+		printerr("SMOKE: failed to change scene, error ", result)
+		quit(1)
+		return
+
+	await scene_changed
+	var game: Node3D = current_scene as Node3D
+	_check("game scene ready", game != null)
+
+	# Initially, ground is at default test level position (0, -0.5, 0)
+	var ground: StaticBody3D = game.get_node_or_null("Level/Ground") as StaticBody3D
+	_check("Ground initially exists", ground != null)
+	_check("Ground initially at (0, -0.5, 0)", ground.position.is_equal_approx(Vector3(0, -0.5, 0)))
+
+	# Create a ChunkScene for chunk (0, 0, 0) with corner objects
+	var chunk_scene := ChunkScene.new()
+	chunk_scene.coord = Vector3i(0, 0, 0)
+	chunk_scene.name = "chunk_0_0_0"
+	game.add_child(chunk_scene)
+
+	# Add lamp post at corner (0.5, 0.5) and corner (31.5, 31.5)
+	var obj_corner1 := WorldObject.new()
+	obj_corner1.id = "lamp1"
+	obj_corner1.type = "prop"
+	obj_corner1.position = Vector3(0.5, 0.5, 0.0)
+	obj_corner1.properties = {"catalog_id": "lamp_post_01"}
+	chunk_scene.add_object(obj_corner1)
+
+	var obj_corner2 := WorldObject.new()
+	obj_corner2.id = "lamp2"
+	obj_corner2.type = "prop"
+	obj_corner2.position = Vector3(31.5, 31.5, 0.0)
+	obj_corner2.properties = {"catalog_id": "lamp_post_01"}
+	chunk_scene.add_object(obj_corner2)
+
+	# Trigger _on_chunk_loaded
+	game.call("_on_chunk_loaded", Vector3i(0, 0, 0), chunk_scene)
+
+	# Verify Ground has moved to center of chunk: (16.0, -0.5, 16.0)
+	_check("Ground moved to chunk center (16, -0.5, 16)", ground.position.is_equal_approx(Vector3(16.0, -0.5, 16.0)))
+
+	var shape_node := ground.find_child("CollisionShape3D", true, false) as CollisionShape3D
+	_check("Ground CollisionShape3D size >= 40x40", shape_node != null and (shape_node.shape as BoxShape3D).size.x >= 40.0 and (shape_node.shape as BoxShape3D).size.z >= 40.0)
+
+	var mesh_node := ground.find_child("MeshInstance3D", true, false) as MeshInstance3D
+	_check("Ground MeshInstance3D size >= 40x40", mesh_node != null and (mesh_node.mesh as BoxMesh).size.x >= 40.0 and (mesh_node.mesh as BoxMesh).size.z >= 40.0)
+
+	# Verify corners are inside ground bounds
+	var half_x: float = (shape_node.shape as BoxShape3D).size.x * 0.5
+	var half_z: float = (shape_node.shape as BoxShape3D).size.z * 0.5
+	var min_gx: float = ground.position.x - half_x
+	var max_gx: float = ground.position.x + half_x
+	var min_gz: float = ground.position.z - half_z
+	var max_gz: float = ground.position.z + half_z
+
+	_check("Corner (0.5, 0.5) is on ground", 0.5 >= min_gx and 0.5 <= max_gx and 0.5 >= min_gz and 0.5 <= max_gz)
+	_check("Corner (31.5, 31.5) is on ground", 31.5 >= min_gx and 31.5 <= max_gx and 31.5 >= min_gz and 31.5 <= max_gz)
+
+	# Verify PlayerSpawn defaulted to chunk center (16, 1.5, 16)
+	var spawn_marker := game.get_node_or_null("Level/PlayerSpawn") as Node3D
+	_check("PlayerSpawn marker is at (16, 1.5, 16)", spawn_marker != null and spawn_marker.global_position.is_equal_approx(Vector3(16.0, 1.5, 16.0)))
+
+	# Now test placed spawn_point object
+	var chunk_scene2 := ChunkScene.new()
+	chunk_scene2.coord = Vector3i(0, 0, 0)
+	chunk_scene2.name = "chunk_with_spawn"
+	game.add_child(chunk_scene2)
+
+	var spawn_obj := WorldObject.new()
+	spawn_obj.id = "spawn1"
+	spawn_obj.type = "spawn_point"
+	spawn_obj.position = Vector3(8.5, 12.5, 0.0)
+	spawn_obj.properties = {"catalog_id": "spawn_point"}
+	chunk_scene2.add_object(spawn_obj)
+
+	game.call("_on_chunk_loaded", Vector3i(0, 0, 0), chunk_scene2)
+	_check("PlayerSpawn moved to placed spawn_point at (8.5, 1.5, 12.5)", spawn_marker != null and spawn_marker.global_position.is_equal_approx(Vector3(8.5, 1.5, 12.5)))
+
+	print("\n=== SMOKE RESULT: %d/%d passed ===" % [_passed, _passed + _failed])
+	if _failed > 0:
+		quit(1)
+	else:
+		quit(0)

scripts/tile_layer_node.gd

@@ -55,6 +55,12 @@ func _create_mesh_for_tile(tile_def: TileDef) -> void:
 	multi_mesh.mesh = _make_unit_cube_mesh()
 	multi_mesh.instance_count = count
 
+	var col_body: StaticBody3D = null
+	if tile_def.solid:
+		col_body = StaticBody3D.new()
+		col_body.name = "collision_%d" % tile_def.id
+		add_child(col_body)
+
 	var instance_idx := 0
 	for z in range(tile_layer.depth):
 		for y in range(tile_layer.height):
@@ -66,6 +72,13 @@ func _create_mesh_for_tile(tile_def: TileDef) -> void:
 				var xform := Transform3D(Basis(), world_pos)
 				multi_mesh.set_instance_transform(instance_idx, xform)
 				instance_idx += 1
+				if col_body != null:
+					var col_shape := CollisionShape3D.new()
+					var box := BoxShape3D.new()
+					box.size = Vector3(TILE_SIZE, TILE_SIZE, TILE_SIZE)
+					col_shape.shape = box
+					col_shape.position = world_pos
+					col_body.add_child(col_shape)
 
 	var mesh_instance := MultiMeshInstance3D.new()
 	mesh_instance.multimesh = multi_mesh