Add node delete action (#13)

* add command to delete selected nodes with X

* add confirmation dialog for deleting nodes except when pressing shift

addons/gd-blender-3d-shortcuts/plugin.gd

@@ -173,6 +173,11 @@ func _forward_3d_gui_input(camera, event):
 								forward = true
 						KEY_H:
 							commit_hide_nodes()
+						KEY_X:
+							if event.shift_pressed:
+								delete_selected_nodes()
+							else:
+								confirm_delete_selected_nodes()
 	else:
 		if event is InputEventKey:
 			# Not sure why event.pressed always return false for numpad keys
@@ -508,6 +513,59 @@ func commit_hide_nodes():
 	undo_redo.add_undo_method(Utils, "hide_nodes", nodes, false)
 	undo_redo.commit_action()
 
+## Opens a popup dialog to confirm deletion of selected nodes.
+func confirm_delete_selected_nodes():
+	var selected_nodes = get_editor_interface().get_selection().get_selected_nodes()
+	if selected_nodes.is_empty():
+		return
+
+	var editor_theme = get_editor_interface().get_base_control().theme
+	var popup = ConfirmationDialog.new()
+	popup.theme = editor_theme
+
+	# Setting dialog text dynamically depending on the selection to mimick Godot's normal behavior.
+	popup.dialog_text = "Delete "
+	var selection_size = selected_nodes.size()
+	if selection_size == 1:
+		popup.dialog_text += selected_nodes[0].get_name()
+	elif selection_size > 1:
+		popup.dialog_text += str(selection_size) + " nodes"
+	for node in selected_nodes:
+		if node.get_child_count() > 0:
+			popup.dialog_text += " and children"
+			break
+	popup.dialog_text += "?"
+
+	add_child(popup)
+	popup.popup_centered()
+	popup.canceled.connect(popup.queue_free)
+	popup.confirmed.connect(delete_selected_nodes)
+	popup.confirmed.connect(popup.queue_free)
+
+## Instantly deletes selected nodes and creates an undo history entry.
+func delete_selected_nodes():
+	var undo_redo = get_undo_redo()
+
+	var selected_nodes = get_editor_interface().get_selection().get_selected_nodes()
+	# Avoid creating an unnecessary history entry if no nodes are selected.
+	if selected_nodes.is_empty():
+		return
+
+	undo_redo.create_action("Delete Nodes", UndoRedo.MERGE_DISABLE)
+	for node in selected_nodes:
+		# We can't free nodes, they must be kept in memory for undo to work.
+		# That's why we use remove_child instead and call UndoRedo.add_undo_reference() below.
+		undo_redo.add_do_method(node.get_parent(), "remove_child", node)
+		undo_redo.add_undo_method(node.get_parent(), "add_child", node, true)
+		undo_redo.add_undo_method(node.get_parent(), "move_child", node, node.get_index())
+		# Every node's owner must be set upon undoing, otherwise, it won't appear in the scene dock
+		# and it'll be lost upon saving.
+		undo_redo.add_undo_method(node, "set_owner", node.owner)
+		for child in Utils.recursive_get_children(node):
+			undo_redo.add_undo_method(child, "set_owner", node.owner)
+		undo_redo.add_undo_reference(node)
+	undo_redo.commit_action()
+
 func revert():
 	var nodes = get_editor_interface().get_selection().get_transformable_selected_nodes()
 	Utils.revert_transform(nodes, _cache_global_transforms)