GameObject custom editor prevents drawing 3D models preview

Hi there!

I'm trying to make a custom editor for GameObject. It works fine, and I'm glad to share the trick with you. But wait, Unity acts really weird when you're using 3D models with a custom editor for GameObject in your project!
As an example, I made the following script, which will list all the components on a selected GameObject:

Code (CSharp):

1. using System;
2. using System.Reflection;
3. using UnityEngine;
4. using UnityEditor;
5.  
6. [CustomEditor(typeof(GameObject))]
7. [CanEditMultipleObjects]
8. public class GameObjectCustomEditorDemo : Editor
9. {
10.     private Editor m_DefaultGameObjectEditor = null;
11.  
12.     private void OnEnable()
13.     {
14.         // Creates the default inspector view of GameObject using reflection (needed to access to the internal UnityEditor classes)
15.         m_DefaultGameObjectEditor = CreateEditor(target, Type.GetType("UnityEditor.GameObjectInspector, UnityEditor"));
16.     }
17.  
18.     private void OnDisable()
19.     {
20.         if (m_DefaultGameObjectEditor != null)
21.         {
22.             // Check if the preview cache property is set
23.             object previewCache = m_DefaultGameObjectEditor.GetType()
24.                 .GetField("m_PreviewCache", BindingFlags.Instance | BindingFlags.NonPublic)
25.                 .GetValue(m_DefaultGameObjectEditor);
26.  
27.             // If the preview cache is not defined, call OnEnable() method to initialize the GameObject editor, avoiding exceptions
28.             if (previewCache == null)
29.                 m_DefaultGameObjectEditor.GetType().GetMethod("OnEnable").Invoke(m_DefaultGameObjectEditor, null);
30.  
31.             DestroyImmediate(m_DefaultGameObjectEditor);
32.         }
33.     }
34.  
35.     protected override void OnHeaderGUI()
36.     {
37.         // Draw the default GameObject editor header
38.         m_DefaultGameObjectEditor.DrawHeader();
39.     }
40.  
41.     public override void OnInspectorGUI()
42.     {
43.         // Draw the default GameObject editor inspector GUI
44.         m_DefaultGameObjectEditor.OnInspectorGUI();
45.  
46.         // Draw a list of all the components on the first selected GameObject
47.         EditorGUILayout.LabelField("Components on this GameObject:", EditorStyles.boldLabel);
48.         EditorGUI.indentLevel++;
49.         Component[] components = (target as GameObject).GetComponents<Component>();
50.         for (int i = 0; i < components.Length; i++)
51.         {
52.             EditorGUILayout.LabelField($"[{i}] {components[i].GetType().Name}");
53.         }
54.         EditorGUI.indentLevel--;
55.         EditorGUILayout.Space();
56.     }
57. }

With this script in your project, you should see the components list in the inspector when you select a GameObject:

Pretty cool, right? This really works like a charm (and the trick is quite the same for other native components by the way)... But there is bad side effects with 3D models:

• Their preview are no more visible in the Project window
• Their preview is not displayed in the Model Importer view (in the Inspector)
• I can't drag and drop them from my Project view to the Scene view (but dragging them to the Hierarchy still works)

Unfortunately, these bugs makes the tool unusable for productions. I searched for a solution by tryings things with reflection and using the Unity's C# reference on GitHub, but that was unsuccessful.

So, I would like to find:

• why Unity behaves that way when creating a custom GameObject editor?
• and how can I fix this issue?

Does someone have at least a track I can explore?
Thanks in advance for any answer!
(and sorry to the Unity Technologies guys who will see this post for doing too many experiments with your wonderful game engine!)​

 

Up

 

I've finally found a solution. I implemented it in the

GameObjectExtensionEditor

of the Core Library of Muffin Dev for Unity

=> https://gitlab.com/muffin-dev/unity...ob/master/Editor/GameObjectExtensionEditor.cs