# PhysicsCallbacks.ITransformChangedCallback

> An interface that when implemented, can be called when using PhysicsWorld.RegisterTransformChange.

## Definition

* **Type:** Interface
* **Namespace:** [Unity.U2D.Physics](/engine/6000.6/script-reference/unity/u2d/physics.md)
* **Assembly:** UnityEngine.PhysicsCore2DModule

```csharp
public interface PhysicsCallbacks.ITransformChangedCallback
```

## Methods

| Method                                                                                                                                   | Description                                                                                                                                                                                                       |
| ---------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [OnTransformChanged](/engine/6000.6/script-reference/unity/u2d/physics/physicscallbacks/itransformchangedcallback/ontransformchanged.md) | Called when a [PhysicsEvents.TransformChangeEvent](/engine/6000.6/script-reference/unity/u2d/physics/physicsevents/transformchangeevent.md) for the object occurs. This will always be called on the main-thread. |