Undo.RecordObject

Parameters

Description

Records any changes done on the object after the RecordObject function.

Almost all property changes can be recorded with this function. The transform parent, AddComponent, object destruction can not be recorded with this function, for that you should use the dedicated functions.

Internally this will create a temporary copy of the object's state and at the end of the frame Unity will diff the state and thus detect what exactly has changed. The changed properties are then recorded on the undo stack. If nothing has actually changed (Binary exact comparison is used for all properties), no undo operation will be stored on the stack.

This is an example of an editor script which allows you to change an effect radius variable. The Undo state is recorded, allowing you to revert the change using the undo system.

//Name this script "EffectRadiusEditor"
using UnityEngine;
using UnityEditor;

[CustomEditor(typeof(EffectRadius))]
public class EffectRadiusEditor : Editor
{
    public void OnSceneGUI()
    {
        EffectRadius t = (target as EffectRadius);

        EditorGUI.BeginChangeCheck();
        float areaOfEffect = Handles.RadiusHandle(Quaternion.identity, t.transform.position, t.areaOfEffect);
        if (EditorGUI.EndChangeCheck())
        {
            Undo.RecordObject(target, "Changed Area Of Effect");
            t.areaOfEffect = areaOfEffect;
        }
    }
}

Place this script on a GameObject to see the area of effect handle, and change the value using the gizmo in the scene view.

//Name this script "EffectRadius"
using UnityEngine;
using System.Collections;

public class EffectRadius : MonoBehaviour {

    public float areaOfEffect = 1;

}