Unity Custom Editor question

Unity Engine
1

Hey there.

I am making a Custom Editor class that links game objects in the scene view using Handles.DrawLine. Each GameObject to be linked has a script attached which contains a list of GameObjects called mpChildren.

The list is filled by dragging and dropping GameObjects from the hierarchy onto the variable in the Inspector. I want to do a check on a GameObject being added to see if it is already in the list. Is there a callback function in the Editor to say when an object has been dropped on a variable in the Inspector?

Cheers,
Johnty

2 
GameObject go = EditorGUILayout.ObjectField(null, typeof(GameObject), true);
if (go != null)
{
   // Do things here.
}

Where it says “Do things here” you would add the GameObject “go” to your list, or check mpChildren.Contains(go), or whatever it is you need to do.

3

Sweet cheers. Is this done in the InspectorGUI function call in the Editor script? And do I need to overwrite the Inspector or will that function just recieve a callback when an ObjectField is changed?

4

Just put it in the OnInspectorGUI. You can add it to the normal Inspector GUI by calling base.OnInspectorGUI() at the top of the method.

private List<GameObject> linkedGameObjects;

public override void OnInspectorGUI()
{
   base.OnInspectorGUI();

   EditorGUILayout.BeginHorizontal();
   EditorGUILayout.PrefixLabel("Add GameObject");
   GameObject go = (GameObject)EditorGUILayout.ObjectField(null, typeof(GameObject), true);
   EditorGUILayout.EndHorizontal();

   if (go != null)
   {
      if (!linkedGameObjects.Contains(go))
         linkedGameObjects.Add(go);
   }

   int removeIndex = -1;
   for (int i = 0; i < linkedGameObjects.Count; i++)
   {
      if (GUILayout.Button(linkedGameObjects[i].name))
      {
         removeIndex = i;
      }
   }

   if (removeIndex > -1)
      linkedGameObjects.RemoveAt(removeIndex);
}

That code can be used to add GameObjects to the script, display the GameObjects linked to the script, and remove them.