Unity editor scripting : how to execute two different actions with the same button? - unity3d

Question

I wrote some code to add a button to my custom editor in Unity. What I'd like is the following. When I click the button once, a component is added, and when I click again the component is removed. In the simple code below, I just try to print "Add" or "Remove" when clicking the button. I noticed that the variable toggleRigidBody takes the value true but then take the value false right after. It doesn't stay "true" even though I never explicitly change it in the code. The "else if" is never fired. I'm not sure why.
using UnityEditor;
using UnityEngine;
using SS3D.Engine.Inventory;
[CustomEditor(typeof(ContainerController))]
public class ContainerControllerEditor : Editor
{
private bool toggleRigidBody = false;
public override void OnInspectorGUI()
{
DrawDefaultInspector();
ContainerController containerController = (ContainerController)target;
Debug.Log(toggleRigidBody);
bool buttonPressed = GUILayout.Button("AddAttachedContainer");
if (buttonPressed && toggleRigidBody == false)
{
Debug.Log("Add");
toggleRigidBody = true;
}
else if (buttonPressed && toggleRigidBody == true)
{
Debug.Log("Remove");
toggleRigidBody = false;
}
}
}
My code only print "Add" when I click the button. What's happening here ?

Answer 1

The main problem here is that the editor instance is created when the object is clicked and the Inspector loaded. And then it is destroyed as soon as the object loses focus and the Inspector not shown for this object anymore.
=> Your flag toggleRigidBody is not persistent!
What you rather want to do is serialize the flag inside your object or even better: Serialize the reference itself.
This way you
Have already access to the reference in your script in case you need it on runtime
Have the reference in the editor for a) checking if it exists and b) being able to remove it directly
So having your class like
public class ContainerController : MonoBehaviour
{
// Store the reference in a field
[SerializeField] private Rigidbody _rigidbody;
...
}
The editor could look like
[CustomEditor(typeof(ContainerController))]
public class ContainerControllerEditor : Editor
{
private SerializedProperty _rigidbody;
ContainerController containerController;
private void OnEnable()
{
_rigidbody = serializedObject.FindProperty("_rigidbody");
containerController = (ContainerController)target;
}
public override void OnInspectorGUI()
{
DrawDefaultInspector();
// Loads all current serialized values from the target into the serialized properties
serializedObject.Update();
// If the _rigidbody field is not assigned
// try GetComponent as fallback
if(!_rigidbody.objectReferenceValue) _rigidbody.objectReferenceValue = containerController.GetComponent<Rigidbody>();
// simply put everything that belongs to one button click inside one if block
// this is easier to maintain and read
// Of course alternatively you could also simply have two completely different buttons to display
// depending on the value of "_rigidbody.objectReferenceValue"
if(GUILayout.Button(_rigidbody.objectReferenceValue ? "Remove Rigidbody" : "Add Rigidbody")
{
// Is there a Rigidbody?
if(_rigidbody.objectReferenceValue)
{
// Yes -> destroy it
// There are two different destroy methods depending whether you are
// in Play mode or Edit mode
if(Application.isPlaying)
{
Destroy(_rigidbody.objectReferenceValue);
}
else
{
DestroyImmediate(_rigidbody.objectReferenceValue);
}
}
// Otherwise the field is currently not set and no component was found using GetComponent
else
{
// Add the component via the ObjectFactory
// this enabled undo/redo and marks the scene dirty etc
// and assign it to the serialized property
_rigidbody.objectReferenceValue = ObjectFactory.AddComponent<Rigidbody>(target.gameObject);
}
}
// Writes back all modified properties to the target and takes care of Undo/Redo and marking dirty
serializedObject.ApplyModifiedProperties ();
}
}

Answer 2

The editor object is created when it's being displayed, and destroyed when it's not, so for your data to persist you will need to store the values somewhere else. So that's definitely what is happening. The easiest way to have a value of a variable to be persistent between sessions you would use EditorPrefs to save the variable values. Thats the easiest way you can go about it, so you would use this to save the toggleRigidBody value.
https://docs.unity3d.com/ScriptReference/EditorPrefs.SetBool.html