feat: Enhance selection and grid functionality in sandbox stage and gizmos

scripts/sandbox_stage.gd

@@ -81,6 +81,7 @@ var _status_label: Label
 var _grid_check: CheckBox
 var _snap_check: CheckBox
 var _grid_size_spin: SpinBox
+var _grid_size_label: Label
 
 var _grid_size: float = DEFAULT_GRID_SIZE
 var _snap_enabled: bool = false
@@ -140,7 +141,13 @@ func _physics_process(_delta: float) -> void:
 # ---------------------------------------------------------------------------
 
 func _input(event: InputEvent) -> void:
-	if event is InputEventMouseButton:
+	if event is InputEventMagnifyGesture:
+		# Touchpad pinch zoom.
+		_set_zoom(_camera.zoom.x * (event as InputEventMagnifyGesture).factor)
+	elif event is InputEventPanGesture:
+		# Touchpad two-finger pan (delta is screen px; ×3 for speed parity).
+		_camera.position -= (event as InputEventPanGesture).delta * 3.0 / _camera.zoom.x
+	elif event is InputEventMouseButton:
 		_handle_mouse_button(event)
 	elif event is InputEventMouseMotion:
 		_handle_mouse_motion(event)
@@ -249,12 +256,16 @@ func _enter_edit_mode() -> void:
 	# so re-assert the authored transform on the next few physics frames.
 	_restore_frames_left = 3
 	_gizmos.set_enabled(true)
+	_apply_grid_settings()
+	_set_build_controls_visible(true)
 
 
 func _enter_play_mode() -> void:
 	_gizmos.set_enabled(false)
 	_selection.clear_selection()
 	set_placement_mode("")
+	_apply_grid_settings()
+	_set_build_controls_visible(false)
 	for node: Node2D in _world_children_selectable():
 		if node is RigidBody2D:
 			(node as RigidBody2D).freeze = false
@@ -384,6 +395,9 @@ func _begin_click_select(world_pos: Vector2, shift: bool) -> void:
 			_selection.toggle_selection(hit)
 			if _selection.is_selected(hit):
 				_gizmos.begin_translate_drag(hit, world_pos)
+		elif _selection.is_selected(hit):
+			# Already selected: keep the whole selection and drag it together.
+			_gizmos.begin_translate_drag(hit, world_pos)
 		else:
 			_selection.select_only(hit)
 			_gizmos.begin_translate_drag(hit, world_pos)
@@ -482,9 +496,9 @@ func _build_ui() -> void:
 	_snap_check.toggled.connect(_on_snap_toggled)
 	hbox.add_child(_snap_check)
 
-	var grid_label := Label.new()
-	grid_label.text = "Size"
-	hbox.add_child(grid_label)
+	_grid_size_label = Label.new()
+	_grid_size_label.text = "Size"
+	hbox.add_child(_grid_size_label)
 
 	_grid_size_spin = SpinBox.new()
 	_grid_size_spin.min_value = MIN_GRID_SIZE
@@ -555,8 +569,8 @@ func _on_grid_size_changed(value: float) -> void:
 	_save_settings()
 
 
-func _on_selection_changed(nodes: Array) -> void:
-	_gizmos.set_target(_selection.get_primary())
+func _on_selection_changed(nodes: Array[Node2D]) -> void:
+	_gizmos.set_targets(nodes)
 	if nodes.is_empty():
 		object_deselected.emit()
 	else:
@@ -568,8 +582,9 @@ func _on_hover_changed(node: Node2D) -> void:
 	_gizmos.set_hover(node)
 
 
-func _on_transform_committed(node: Node2D) -> void:
-	_save_object_state(node)
+func _on_transform_committed(nodes: Array[Node2D]) -> void:
+	for node: Node2D in nodes:
+		_save_object_state(node)
 
 # ---------------------------------------------------------------------------
 # Helpers
@@ -577,7 +592,12 @@ func _on_transform_committed(node: Node2D) -> void:
 
 func _set_zoom(value: float) -> void:
 	var z := clampf(value, min_zoom, max_zoom)
+	var old_zoom := _camera.zoom.x
+	if is_equal_approx(z, old_zoom):
+		return
+	var mouse_world := _camera.get_global_mouse_position()
 	_camera.zoom = Vector2(z, z)
+	_camera.position = mouse_world - (mouse_world - _camera.position) * (old_zoom / z)
 
 
 func _is_mouse_over_ui() -> bool:
@@ -594,10 +614,24 @@ func _apply_grid_settings() -> void:
 	if _grid != null:
 		_grid.grid_size = _grid_size
 		_grid.enabled = _show_grid
+		_grid.visible = _show_grid and current_mode == StageMode.EDIT
 	if _gizmos != null:
 		_gizmos.snap_size = _grid_size if _snap_enabled else 0.0
 
 
+func _set_build_controls_visible(visible: bool) -> void:
+	for btn: Button in _palette_buttons.values():
+		btn.visible = visible
+	if _grid_check != null:
+		_grid_check.visible = visible
+	if _snap_check != null:
+		_snap_check.visible = visible
+	if _grid_size_spin != null:
+		_grid_size_spin.visible = visible
+	if _grid_size_label != null:
+		_grid_size_label.visible = visible
+
+
 ## Direct Node2D children of World, excluding the ragdoll body container.
 func _world_children_selectable() -> Array[Node2D]:
 	var result: Array[Node2D] = []