Beta 12: Can someone elaborate on added "Support for reparenting prefab root in Awake and OnEnable"?

As of Beta 11 I directly patch UnityEditor assembly with Harmony patcher to support some prefabs requiring custom enveloping objects (thanks to Shaun-Peoples for showing me how to do that!). I'm specifically targeting MovePrefabRootToEnvironmentScene in PrefabStageUtility: that's where standard UI gets special treatment, so I append my code there to give special parenting treatment to other systems like NGUI.

Am I understanding right that in Beta 12 its possible to accomplish the same thing using OnAwake/OnEnable? If so, can somebody post an example?

For context, here is what I do to prefabs in the aforementioned Beta 11 patch:

Code (csharp):

1. [HarmonyPatch (typeof (PrefabStageUtility))]
2. [HarmonyPatch ("MovePrefabRootToEnvironmentScene")]
3. public class PatchSceneRoot
4. {
5.     static void Postfix (Scene __result, GameObject prefabInstanceRoot)
6.     {
7.         var instanceRoot = prefabInstanceRoot;
8.         var scene = __result;
9.  
10.         var rootsInPrefab = instanceRoot.GetComponentsInChildren<UIRoot> (true);
11.         var panelsInPrefab = instanceRoot.GetComponentsInChildren<UIPanel> (true);
12.  
13.         bool missingRoot = rootsInPrefab.Length == 0;
14.         bool missingPanel = panelsInPrefab.Length == 0;
15.  
16.         if (!missingRoot && !missingPanel)
17.             return;
18.  
19.         GameObject container = EditorUtility.CreateGameObjectWithHideFlags ("UIRoot (Environment)", HideFlags.DontSave);
20.         container.layer = LayerMask.NameToLayer ("UI");
21.  
22.         if (missingRoot)
23.             container.AddComponent<UIRoot> ();
24.  
25.         if (missingPanel)
26.             container.AddComponent<UIPanel> ();
27.  
28.         SceneManager.MoveGameObjectToScene (container, scene);
29.         instanceRoot.transform.SetParent (container.transform, false);
30.     }
31. }

I'd certainly be happy if I could move that stuff into normal events instead of a brittle patch targeting constantly changing private parts of the assembly.

 

I’m curious, is there any way to reparent to an object that already exists in the environment scene in Awake? It seems the scene isn’t ready for a GetRootGameObjects() call yet, so I haven’t found a way to get a reference to an existing object. This would be pretty useful in many UI scenarios because you could have “slots” set up for different UI components.

If not, I think the prefab instantiation might be a suitable alternative for what I’m trying to do, assuming you can set an object inside it as the parent). Basically I’d like Canvas -> Container -> Prefab Root.

Any thoughts welcome.

 

Following up on my last comment, for anybody who might find it useful - here's my current approach to cover the more general UI cases. This seems to me much more flexible than setting a single scene in the project settings, and I'm SUPER happy this change made it in.

It would be cool, for future versions, to maybe have this functionality as an attribute. For example, [UseEnvironmentPrefabForEditing("path/to/prefab", container="MyContainer")]. Or maybe a prefab metadata setting so it's not tied to a single component.

Code (CSharp):

1. #if UNITY_EDITOR
2. using UnityEditor;
3. using UnityEditor.Experimental.SceneManagement;
4. using UnityEngine;
5. using UnityEngine.SceneManagement;
6.  
7. public static class PrefabEditorHelper {
8.     public static void UsePrefabAsset(GameObject obj, string prefabPath, string parentName = "PrefabContainer") {
9.         var prefabStage = PrefabStageUtility.GetPrefabStage(obj);
10.         if (prefabStage != null && obj.transform.parent == null) {
11.             var instance = PrefabUtility.InstantiatePrefab(
12.                 AssetDatabase.LoadAssetAtPath<GameObject>(prefabPath)) as GameObject;
13.             if (instance) {
14.                 SceneManager.MoveGameObjectToScene(instance, obj.scene);
15.                 var container = FindObjectRecursive(instance, parentName);
16.                 if (container) {
17.                     obj.transform.SetParent(container.transform, false);
18.                 }
19.                 else {
20.                     Debug.LogWarning("No object named " + parentName + " found in environment prefab " + prefabPath);
21.                 }
22.             }
23.             else {
24.                 Debug.LogWarning("Could not find environment prefab: " + prefabPath);
25.             }
26.         }
27.     }
28.    
29.     static GameObject FindObjectRecursive(GameObject obj, string name) {
30.         if (obj.name == name)
31.             return obj;
32.        
33.         for (var i = 0; i < obj.transform.childCount; i++) {
34.             var go = FindObjectRecursive(obj.transform.GetChild(i).gameObject, name);
35.             if (go != null)
36.                 return go;
37.         }
38.  
39.         return null;
40.     }
41. }
42. #endif

Code (CSharp):

1. #if UNITY_EDITOR
2.     void Awake() {
3.         PrefabEditorHelper.UsePrefabAsset(gameObject, "Assets/Prefabs/Editor/SlideEditor.prefab");
4.     }
5. #endif