Undo

class in UnityEditor

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Description

Lets you register undo operations on specific objects you are about to perform changes on.

The Undo system stores delta changes in the undo stack.

Undo operations automatically combine together based on events. For example, mouse down events split undo groups. Grouped undo operations appear and work as a single undo. To control grouping manually, use Undo.IncrementCurrentGroup.

By default, the name shown in the UI is selected from the actions from the group using a hardcoded ordering of the different kinds of actions. To manually set the name, use Undo.SetCurrentGroupName.

Undo operations store either per property or per object state. They scale well with any Scene size.

The most important operations are outlined below:

Modify object properties:
Undo.RecordObject (myGameObject.transform, "Zero Transform Position");
myGameObject.transform.position = Vector3.zero;

Add a component:
Undo.AddComponent<Rigidbody>(myGameObject);

Create a new GameObject:
var go = new GameObject();
Undo.RegisterCreatedObjectUndo (go, "Created go");

Destroy a GameObject or component:
Undo.DestroyObjectImmediate (myGameObject);

Change transform parenting:
Undo.SetTransformParent (myGameObject.transform, newTransformParent, "Set new parent");

Static Properties

Property	Description
isProcessing	Returns true if the editor is currently processing undo or redo operations, false otherwise.
postprocessModifications	Callback that is triggered whenever a new set of property modifications is created.
undoRedoEvent	Callback that is triggered after any undo or redo event.
undoRedoPerformed	Callback that is triggered after an undo or a redo was executed.
willFlushUndoRecord	Invoked before the Undo system performs a flush.

Static Methods

Method	Description
AddComponent	Adds a component to the game object and registers an undo operation for this action.
ClearAll	Removes all undo and redo operations from respectively the undo and redo stacks.
ClearUndo	Removes all Undo operation for the identifier object registered using Undo.RegisterCompleteObjectUndo from the undo stack.
CollapseUndoOperations	Collapses all undo operations down to group index together into one step.
DestroyObjectImmediate	Destroys the object and records an undo operation so that it can be recreated.
FlushUndoRecordObjects	Ensure objects recorded using RecordObject or RecordObjects are registered as an undoable action. In most cases there is no reason to invoke FlushUndoRecordObjects since it's automatically done right after mouse-up and certain other events that conventionally marks the end of an action.
GetCurrentGroup	Unity automatically groups undo operations by the current group index.
GetCurrentGroupName	Get the name that will be shown in the UI for the current undo group.
IncrementCurrentGroup	Unity automatically groups undo operations by the current group index.
MoveGameObjectToScene	Move a GameObject from its current Scene to a new Scene. It is required that the GameObject is at the root of its current Scene.
PerformRedo	Perform an Redo operation.
PerformUndo	Perform an Undo operation.
RecordObject	Records any changes done on the object after the RecordObject function.
RecordObjects	Records multiple undoable objects in a single call. This is the same as calling Undo.RecordObject multiple times.
RegisterChildrenOrderUndo	Stores a copy of the order of the object's children on the undo stack.
RegisterCompleteObjectUndo	Stores a copy of the object states on the undo stack.
RegisterCreatedObjectUndo	Registers an undo operation to undo the creation of an object.
RegisterFullObjectHierarchyUndo	Copy the states of a hierarchy of objects onto the undo stack.
RegisterImporterUndo	Copies the state of the importer for the given asset path.
RevertAllDownToGroup	Performs all undo operations up to the group index without storing a redo operation in the process.
RevertAllInCurrentGroup	Performs the last undo operation but does not record a redo operation.
SetCurrentGroupName	Set the name of the current undo group.
SetSiblingIndex	Sets the sibling index of transform and records an undo operation.
SetTransformParent	Sets the parent of transform to the new parent and records an undo operation.

Delegates

Delegate	Description
PostprocessModifications	Delegate used for postprocessModifications.
UndoRedoCallback	Delegate used for undoRedoPerformed.
UndoRedoEventCallback	Delegate used for undoRedoEvent.
WillFlushUndoRecord	Delegate used for willFlushUndoRecord.

Is something described here not working as you expect it to? It might be a Known Issue. Please check with the Issue Tracker at issuetracker.unity3d.com.

Scripting API

Undo

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Description

Static Properties

Static Methods

Delegates