Not sure how to use the undo system.

[DizzyTornado]

How exactly do I get this to work, I copied most of it from the documentation, can someone help me out?

using UnityEditor;
using UnityEngine;

public class EasymapEditor : MonoBehaviour 
{
	[MenuItem("Tools/EasyMap")]
	static void EasyMap ()
	{
		//print ("EasyMap Spawned!");
		//Instantiate (Resources.Load ("EasyMap", typeof(GameObject)));
		//Undo.RegisterCreatedObjectUndo(EasyMap, "Create " + EasyMap);
		Instantiate (Resources.Load ("EasyMap", typeof(GameObject)));
		Undo.RegisterCreatedObjectUndo (EasyMap, "Create " + EasyMap.//EasyMap);
		Selection.activeObject = EasyMap;
	}
}

I know the error is were I put the two slashes, I put EasyMap there because I wasn’t sure what else to type there.

[Bunny83]

First of all, don’t use Instantiate inside Editor code. Instantiate will break the prefab connection. Use PrefabUtility.InstantiatePrefab.

Next thing is you don’t do anything with the instance that the method returns. That’s the instance you want to register to the Undo system with Undo.RegisterCreatedObjectUndo.

GameObject prefab = (GameObject)Resources.Load ("EasyMap", typeof(GameObject));
GameObject instance = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
Undo.RegisterCreatedObjectUndo (instance, "Create  EasyMap");
Selection.activeObject = instance;

This of course assumes that you have a prefab inside the resources folder that is named “EasyMap”.

[thor348k]

Here is your code with a few changes. Notice the new line:

Undo.IncrementCurrentGroup();

It allows for a “single object undo”, so only the next change will be undone.
Hope this helps!

 using UnityEditor;
 using UnityEngine;
 
 public class EasymapEditor : MonoBehaviour 
 {
     [MenuItem("Tools/EasyMap")]
     static void EasyMap ()
     {
         // single undo
         Undo.IncrementCurrentGroup();

         //print ("EasyMap Spawned!");
         //Instantiate (Resources.Load ("EasyMap", typeof(GameObject)));
         Instantiate (Resources.Load ("EasyMap", typeof(GameObject)));

         // add for undo
         Undo.RegisterCreatedObjectUndo(EasyMap, "Create" + EasyMap.name);

         Selection.activeObject = EasyMap;
     }
 }