How can I implement an undo feature in my game editor similar to the Ctrl+Z shortcut?

Implementing an Undo Feature in Unity Game Editor

Creating an undo feature akin to the Ctrl+Z shortcut in Unity involves careful management of object states and actions. Below is a step-by-step guide:

1. Understanding the Command Pattern

The Command Pattern is pivotal for implementing undo functionality. This design pattern encapsulates a request as an object, allowing for parameterization of clients with queues, requests, and operations.

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public interface ICommand { void Execute(); void Undo(); }

Implement this interface with classes for each action you want to support undo functionality, such as move, rotate, or delete.

2. Storing Commands

Create a stack to store executed commands. This stack allows you to ‘pop’ commands and undo them as needed.

Stack _commandHistory = new Stack();

3. Implementing Undo Logic

Ensure that each command object can undo its operation. For instance:

public class MoveCommand : ICommand { private Transform _entity; private Vector3 _oldPosition; private Vector3 _newPosition; public MoveCommand(Transform entity, Vector3 newPosition) { _entity = entity; _oldPosition = entity.position; _newPosition = newPosition; } public void Execute() { _entity.position = _newPosition; } public void Undo() { _entity.position = _oldPosition; } }

4. Triggering Undo

Bind the undo functionality to a keyboard shortcut, such as Ctrl+Z, within Unity’s Input system:

if (Input.GetKeyDown(KeyCode.Z) && Input.GetKey(KeyCode.LeftControl)) { if (_commandHistory.Count > 0) { var command = _commandHistory.Pop(); command.Undo(); } }

5. Extending to Redo

To implement redo functionality, maintain a secondary stack for undone commands. Push commands onto this stack whenever an undo is performed and pop from it during redo operations.

Stack _redoStack = new Stack();

6. Integrating with Unity Editor

Use Unity’s Editor scripting capabilities to integrate this functionality into the custom game editor, ensuring seamless operation for non-runtime use.

Remember to handle complexities such as compound commands where multiple actions need to be undone or redone together, and potentially visual feedback in the editor to indicate successful undo/redo actions.