Unity 3D - Have a Vector3 attribute on inspector that behaves as GameObject's Transform position Vector3

Question

As the title suggests, I am looking to serialize on the Inspector a Vector3 that behaves just as the Transform's position Vector3:

• If you modify the position Vector3, the GameObject positions itself according to the World Position.
• If you move the GameObject on the scene by picking the handles, the GameObject moves, and the position Vector3 gets modified equal to the GameObject's position.

So, is there a way I can constrain a serialized Vector3, so if I modify it on the inspector I can change the GameObject's position, like this:

[ExecuteInEditMode]
public class LameExample : MonoBehaviour
{
    public Vector3 transformPosition;

    private void Update()
    {
        if(modifyingVectorOnInspector)
        transform.position = transformPosition;
        else if(gameObjectIsBeingMovedOnScene)
        transformPosition = transform.position;
    }
}

I've tried an approach using Selection.contains(gameObject), but that does not take into account if it is dragged by the handles.

Thanks in advance for your help.

Answer 1

This seems to work, using the Reset method to initialize the position when the component is added, and OnValidate to react to changes made in the inspector.

[ExecuteInEditMode]
public class PositionMatch : MonoBehaviour {

    public Vector3 position;

#if UNITY_EDITOR
    void Reset() {
        position = transform.position;
    }

    void OnValidate() {
        if(transform.position != position) {
            UnityEditor.Undo.RecordObject(transform, "change position via variable.");
            transform.position = position;
        }
    }   

    void Update () {
        if(transform.position != position) {
            UnityEditor.Undo.RecordObject(this, "change position via Transform.");
            position = transform.position;
        }
    }
#endif
}

Note that Unity's == operator for Vector3s has a little tolerance. If you don't want that, check them componentwise or validate that their difference has zero squared magnitude.