Implementing an Undo Feature in a Game Editor with Ctrl + Z
Understanding the Undo Functionality
Implementing undo functionality in your game editor allows users to reverse their actions, providing flexibility and a safeguard against errors. The Ctrl + Z command is traditionally used to trigger this action, making it a widely recognized and intuitive shortcut.
Designing the Undo System
The first step in implementing undo functionality is designing an effective system that tracks changes to the application state. This typically involves:
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- Command Pattern: Encapsulate each action as an object that includes methods for executing and undoing the action.
- State Stack: Maintain a stack of application states or commands. Each time a change is made, push a snapshot onto the stack.
- Inverse Operations: Define inverse operations that can revert the changes an action has made.
Implementing in Unity
Unity provides multiple ways to store and manage object states:
class EditorState { public Vector3 position; public Quaternion rotation; // Additional state data } Stack<EditorState> stateStack = new Stack<EditorState>();Each time an object is manipulated, save its state:
public void SaveState(GameObject obj) { EditorState state = new EditorState { position = obj.transform.position, rotation = obj.transform.rotation }; stateStack.Push(state); }Executing Undo Operations
To perform an undo operation, pop the last stored state from the stack and apply it:
public void Undo() { if (stateStack.Count > 0) { EditorState state = stateStack.Pop(); ApplyState(state); } } private void ApplyState(EditorState state) { // Example applying state to an object transform.position = state.position; transform.rotation = state.rotation; }Keyboard Shortcuts and Event Handling
To handle Ctrl + Z, implement an input checking logic within Unity’s Update method:
void Update() { if (Input.GetKey(KeyCode.LeftControl) && Input.GetKeyDown(KeyCode.Z)) { Undo(); } }