unity conditional fields custom editor - unity3d

Question

my goal:
i have a script
public class MyScript: MonoBehaviour
{
public bool A;
public bool B;
}
I need B to be visible only if A is TRUE
i'de done an extention to the script and added UnityEditor in the title
[CustomEditor(typeof(MyScript))]
public class MyEditor : Editor
{
public override void OnInspectorGUI()
{
base.OnInspectorGUI();
MyScript tool = (MyScript) target;
tool.A = GUILayout.Toggle(tool.A, "Flag");
if(tool.A)
{
tool.B= EditorGUILayout.Toggle(tool.B, "Flag");
}
}
}
but nothing really changed.
what did i do wrong?

Answer 1

First of all your class definition is wrong. You either need [Serializable] or the class should inherit from MonoBehaviour if it shall be attached to a GameObject. Either way remove the ()
[Serializable]
public class MyScript
{
public bool A;
public bool B;
}
or
public class MyScript : MonoBehaviour
{
public bool A;
public bool B;
}
Then note that a Custom Editor is only for classes inherting from either a MonoBehaviour or a ScriptableObject. In other cases you will rather have to implement a Custom PropertyDrawer.
You should always try to not directly make changes in the target. You would have to handle a lot of things like marking as dirty, undo/redo etc by yourself...
Rather always go through SerializedPropertys.
Also note that base.OnInspectorGUI(); will draw the default inspector
So assuming MyScript is a MonoBehaviour class
[CustomEditor(typeof(MyScript))]
public class MyEditor : Editor
{
SerializedProperty a;
SerializedProperty b;
// is called once when according object gains focus in the hierachy
private void OnEnable()
{
// link serialized properties to the target's fields
// more efficient doing this only once
a = serializedObject.FindProperty("A");
b = serializedObject.FindProperty("B");
}
public override void OnInspectorGUI()
{
// fetch current values from the real instance into the serialized "clone"
serializedObject.Update();
// Draw field for A
EditorGUILayout.PropertyField(a);
if(a.boolValue)
{
// Draw field for B
EditorGUILayout.PropertyField(b);
}
// write back serialized values to the real instance
// automatically handles all marking dirty and undo/redo
serializedObject.ApplyModifiedProperties();
}
}
Or if MyScript is actually not a MonoBehaviour then as PropertyDrawer which works basically very similar except you have to use the EditorGUI versions of the fields always requiring a position Rect as parameter:
[CustomPropertyDrawer(typeof(MyScript), true)]
public class MyEditor : PropertyDrawer
{
private bool isUnFolded;
public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
{
// draw folder for the entire class
isUnFolded = EditorGUI.Foldout(new Rect(position.x, position.y, position.width, EditorGUIUtility.singleLineHeight), isUnFolded, label);
// go to the next line
position.y += EditorGUIUtility.singleLineHeight;
// only draw the rest if unfolded
if (isUnFolded)
{
// draw fields indented
EditorGUI.indentLevel++;
// similar to before get the according serialized properties for the fields
var a = property.FindPropertyRelative("A");
var b = property.FindPropertyRelative("B");
// Draw A field
EditorGUI.PropertyField(new Rect(position.x, position.y, position.width, EditorGUIUtility.singleLineHeight), a);
position.y += EditorGUIUtility.singleLineHeight;
if (a.boolValue)
{
// Draw B field
EditorGUI.PropertyField(new Rect(position.x, position.y, position.width, EditorGUIUtility.singleLineHeight), b);
}
// reset indentation
EditorGUI.indentLevel--;
}
}
// IMPORTANT you have to implement this since your new property is
// higher then 1 single line
public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
{
// default is 1 single line
var height = 1;
// if unfolded at least 1 line more, if a is true 2 lines more
if(isUnFolded) height += (property.FindPropertyRelative("A").boolValue ? 2 : 1);
return height * EditorGUIUtility.singleLineHeight;
}
}