How to draw with OnPreviewGUI?

Unity Engine
1

I have a custom asset that internally keeps a Mesh object. I have a custom inspector UI that I use to modify the asset and wanted to add a preview so you could see the mesh being generated. But I can’t find any examples or help on how I can do this. Any pointers?

2

Adding this post to clarify how Editor.OnPreviewGUI and Editor.OnInteractivePreviewGUI work. Please note that, according to the documentation, inspector previews are limited to the primary editor of persistent objects: GameObjectInspector, MaterialEditor, TextureInspector. This means that it is currently not possible for a component to have its own inspector preview. Here is an example:

using UnityEngine;
using UnityEditor;

public class GameObjectEditorWindow: EditorWindow {
	
	GameObject gameObject;
	Editor gameObjectEditor;
	
	[MenuItem("Window/GameObject Editor")]
	static void ShowWindow() {
		GetWindow<GameObjectEditorWindow>("GameObject Editor");	
	}
	
	void OnGUI() {
		gameObject = (GameObject) EditorGUILayout.ObjectField(gameObject, typeof(GameObject), true);
		
		if (gameObject != null) {
			if (gameObjectEditor == null)
				gameObjectEditor = Editor.CreateEditor(gameObject);
			
			gameObjectEditor.OnPreviewGUI(GUILayoutUtility.GetRect(500, 500), EditorStyles.whiteLabel);
		}
	}
}
3

Hey Nick. Sometimes I wish a lot of the Unity features were more like XNA. :smile:

4

Hi Nick, I’ve just finished my own preview asset. Maybe it will be useful for you: Powerful Preview - Extend your assets with a preview. - Community Showcases - Unity Discussions.

5

UPD: Solved - forgot to call textute.Apply();

I still cannot give the idea how to draw inside the OnPreviewGUI.

This code shows only grey preview, while I expect to see green area:

using UnityEditor;
using UnityEngine;

/// <summary>
/// Inspector for .SVG assets
/// </summary>
[CustomEditor(typeof(DefaultAsset))]
public class GrapfVizEditor : Editor
{
    public override bool HasPreviewGUI()
    {
        return true;
    }

    public override void OnPreviewGUI(Rect r, GUIStyle background)
    {
        var path = AssetDatabase.GetAssetPath(target);
        if (path.EndsWith(".gv"))
        {
            var texture = new Texture2D(1, 1);
            texture.SetPixel(1, 1, Color.green);
            texture.Apply(); // <- missed that part
            GUI.DrawTexture(r, texture, ScaleMode.StretchToFill, false);
        }
    }

}