Question by TheArtyMorty · Apr 19, 2020 at 07:05 PM · c#custom editor propertydrawer

Inheritance, List and CustomPropertyDrawer

Hi Everyone, This is my first question here, and I usually prefer to try and search for a solution myself, but this time I've been stuck for a few hours and I'm sure I either do something wrong, or just miss a simple tip to go in the right direction.

Here is my problem:

I have an Object (Spell) that contains a List of Effect. An Effect can be anything, but consider that I have 3 possibles Effects : Heal, Damage, Armor.

I have something that look like this for my spell :

 public class Spell : ScriptableObject
 {
     public string Name;
     public int Cost;
 ...
     public List<Effect> Effects;
 }

And my effects all inherit from a BaseClass Effect :

 public class Effect
 {
     public int Value;
    ...
 }
 
 public class DamageEffect : Effect
 {
     public bool IgnoreArmor;
     public bool CanCrit;
    ...
 }

Now my issue is that I want to display my Effect list with a custom Editor, and I want each Effect to appear differently in the custom editor. It seems I can use CustomPropertyDrawers for each of my effects, and that works well... when I'm not using a List.

Since I'm using a List, I somehow want it to display my Effect using the specialized PropertyDrawer.

Currently my PropertyDrawer looks like that :

  // DamageEffectDrawer
     [CustomPropertyDrawer(typeof(DamageEffect))]
     public class DamageEffectDrawer : PropertyDrawer
     {
         public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
         {
             EditorGUI.BeginProperty(position, label, property);
 
             EditorGUILayout.LabelField("Damage Effect", EditorStyles.whiteLabel);
             EditorGUILayout.PropertyField(property.FindPropertyRelative("Value"));
             EditorGUILayout.PropertyField(property.FindPropertyRelative("IgnoreArmor"));
 ...
             EditorGUI.EndProperty();
         }
     }

And my CustomEditor for Spells looks like that :

 [CustomEditor(typeof(Spell))]
 public class SpellCustomEditor : Editor
 {
     private eEffectType _effectToAdd = eEffectType.Unknown;
 
     override public void OnInspectorGUI()
     {
         var spell = target as Spell;
         EditorGUI.BeginChangeCheck();
         SerializedObject spellObject = new UnityEditor.SerializedObject(spell);
 
         EditorGUILayout.LabelField("General Options", EditorStyles.boldLabel);
         spell.Name = EditorGUILayout.TextField("Spell Name : ", spell.Name);
         spell.Cost = EditorGUILayout.IntField("Spell Cost : ", spell.Cost);
         ....
 
         EditorGUILayout.LabelField("Effects : ", EditorStyles.boldLabel);
         _effectToAdd = (eEffectType)EditorGUILayout.EnumPopup("Effect Type : ", _effectToAdd);
         if (GUILayout.Button("Add effect"))
         {
             spell.AddEffect(_effectToAdd);
         }
 
         for (int i =0; i < spell.Effects.Count; i++)
         {
             SerializedProperty myEffect = spellObject.FindProperty("Effects").GetArrayElementAtIndex(i);
             EditorGUILayout.PropertyField(myEffect);
             
             if (GUILayout.Button("Remove effect"))
             {
                 spell.RemoveEffect(i);
             }
         }
 
         if (EditorGUI.EndChangeCheck())
         {
             spellObject.ApplyModifiedProperties();
         }
         EditorUtility.SetDirty(target);
     }
 }

I get in trouble when I do EditorGUILayout.PropertyField(myEffect); Obviously at this point it only knows it's an Effect, and so doesn't display it as a DamageEffect (or whatever).

Does anyone has a smart suggestion on how I could handle that? Maybe I went completely in the wrong direction in the first place.

Thank you for reading, and for any suggestion you might have. Have a nice evening !

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