Problems with AssetPreview.GetAssetPreview

Hey guys

I have been experimenting with AssetPreview.GetAssetPreview and am confused as to why the following script does not work as I had expected. Instead of gradually caching previews as they are loaded, previews simply vanish. Previews that have been loaded and displayed are actually becoming null which naturally forces them to get loaded and displayed again.

Here is the script:

Code (csharp):

1.  
2. using UnityEngine;
3. using UnityEditor;
4.  
5. public class TestPreviewWindow : EditorWindow {
6.  
7.     [MenuItem("Window/Test Preview")]
8.     private static void ShowWindow() {
9.         GetWindow<TestPreviewWindow>("Test Preview");
10.     }
11.  
12.     private GameObject[] prefabs;
13.     private Texture2D[] prefabPreviews;
14.  
15.     private void OnEnable() {
16.         prefabs = Resources.FindObjectsOfTypeAll(typeof(GameObject)) as GameObject[];
17.         prefabPreviews = new Texture2D[prefabs.Length];
18.     }
19.  
20.     private Vector2 _scrolling;
21.  
22.     public void OnGUI() {
23.         int columns = Mathf.FloorToInt(position.width / 128);
24.  
25.         _scrolling = GUILayout.BeginScrollView(_scrolling);
26.         {
27.             GUILayout.BeginHorizontal();
28.  
29.             for (int i = 0; i < prefabs.Length; ++i) {
30.                 if (i % columns == 0) {
31.                     GUILayout.EndHorizontal();
32.                     GUILayout.BeginHorizontal();
33.                 }
34.  
35.                 if (prefabPreviews[i] == null) {
36.                     prefabPreviews[i] = AssetPreview.GetAssetPreview(prefabs[i]);
37.                     if (AssetPreview.IsLoadingAssetPreview(prefabs[i].GetInstanceID())) {
38.                         Repaint();
39.                         GUILayout.Box("Loading...", GUILayout.Width(128), GUILayout.Height(128));
40.                     }
41.                     else {
42.                         GUILayout.Box("?", GUILayout.Width(128), GUILayout.Height(128));
43.                     }
44.                 }
45.                 else {
46.                     GUILayout.Box(prefabPreviews[i], GUILayout.Width(128), GUILayout.Height(128));
47.                 }
48.             }
49.  
50.             GUILayout.EndHorizontal();
51.         }
52.         GUILayout.EndScrollView();
53.     }
54.  
55. }
56.  

Here is the problem:

To reproduce the problem:

• Load AngryBots example project in Unity 4.
• Ensure that a large number of prefab assets have been loaded by selecting them in the inspector. There is probably an easier way to quickly load all prefabs, but I took the lowtech route to demonstrate in the above video.
• Add the above editor script and select Window|Test Preview.
• Scroll up/down to observe oddness.

Any ideas as to why this doesn't work as expected? Is anybody from Unity able to confirm how the preview functions are supposed to work?

Many thanks

 

Hi. It looks like this is a bug in Unity. Duplicate here: http://answers.unity3d.com/questions/259608/editorutiltiygetassetpreviewobject-asset.html

 

Hmm, seems like the problem is still not fixed

Any news here?

 

As a notice, I have found that if you set a custom indicator for an asset, it doesn't load the preview.

 

oldish thread, but you need to use the Editor class

Code (csharp):

1.  
2. Editor
3.  
4.  

 

The cause of the flicking is that Unity has a small cache size which is shared amongst all editor windows when using their API. Recently they have added an API to customize this; but I still ran into issues when using previews in multiple editor windows.

AssetPreview.SetPreviewTextureCacheSize

I have since rolled my own asset preview API which avoids all of these issues and provides a lot more control over how the previews are rendered and at which size they are rendered.