Unity自定义检查器，允许选定的子对象

Question

I'm trying to make a custom inspector for a PlayerInventory class. The PlayerInventory class consists of a list of items (which are ScriptableObjects ), along with a quantity of each item, like this:

public class Item : ScriptableObject
{
   public string description;
   public Sprite picture;
}

public class InventoryItem : ScriptableObject
{
   // A reference to the Item object that contains the item's description, 
   // picture, stats, etc.
   public Item item;

   // The quantity of this item that the player has in his inventory
   public int quantity;
}

[CreateAssetMenu(menuName = "Player/Player Inventory")]
public class PlayerInventory : ScriptableObject
{
   // The list of each distinct item that the player has in his inventory,
   // along with the quantity of each item
   public List<InventoryItem> items;
}

I created an instance of PlayerInventory as a game asset. By default, the Inspector shows a list of InventoryItem s. However, what I want is for the Inspector to show each InventoryItem element with a field to select an Item for it, a field to enter a quantity, and a "delete" button.

Here's a visual example of what I'm trying to achieve, along with my current code below. The problem with this screenshot is that Unity is making me select an InventoryItem object for each element. I want to be able to select an Item object for each element. The second problem I'm having is I don't know how to set an EditorGUILayout.TextField to the InventoryItem.quantity property because I don't know how to convert the SerializedProperty to an InventoryItem object.

[CustomEditor(typeof(PlayerInventory))]
public class PlayerInventoryEditor : Editor
{
   public override void OnInspectorGUI()
   {
       this.serializedObject.Update();

       SerializedProperty items = this.serializedObject.FindProperty("items");
       for (int i = 0; i < items.arraySize; i++)
       {
           EditorGUILayout.BeginHorizontal();
           EditorGUILayout.LabelField("Item", GUILayout.Width(50));

           // I don't know how to make this line reference the child "item"
           // field of the current InventoryItem
           EditorGUILayout.PropertyField(items.GetArrayElementAtIndex(i), GUIContent.none, GUILayout.Width(170));

           EditorGUILayout.LabelField("    Quantity", GUILayout.Width(80));

           // I don't know how to set the text field to the "quantity" field
           // of the current InventoryItem
           EditorGUILayout.TextField("0", GUILayout.Width(50));

           EditorGUILayout.LabelField("", GUILayout.Width(20));
           GUILayout.Button("Delete Item");               
           EditorGUILayout.EndHorizontal();
       }

       GUILayout.Button("Add Item");
   }
}

Answer 1

Classes must be serializable to appear in the Inspector. See Serializable

Edit . Following further discussion in the comments below, here's the full snippet;

Standard class marked Serializable ;

[System.Serializable]
public class InventoryItem
{
    public Item item;
    public int quantity;
}

With PlayerInventoryEditor;

public override void OnInspectorGUI ()
{
    this.serializedObject.Update();

    SerializedProperty items = this.serializedObject.FindProperty("items");

    for (int i = 0; i < items.arraySize; i++)
    {
        SerializedProperty item = items.GetArrayElementAtIndex(i);

        EditorGUILayout.BeginHorizontal();
        EditorGUILayout.LabelField("Item", GUILayout.Width(50));
        EditorGUILayout.PropertyField(item.FindPropertyRelative("item"), GUIContent.none, GUILayout.Width(170));
        EditorGUILayout.LabelField("    Quantity", GUILayout.Width(80));
        EditorGUILayout.IntField(item.FindPropertyRelative("quantity").intValue, GUILayout.Width(50));

        EditorGUILayout.LabelField("", GUILayout.Width(20));
        GUILayout.Button("Delete Item");
        EditorGUILayout.EndHorizontal();
    }

    GUILayout.Button("Add Item");
}

Answer 2

You can use FindPropertyRelative

//...
EditorGUILayout.PropertyField(
    items.GetArrayElementAtIndex(i).FindPropertyRelative("item"),
    new GUIContent("Item"), 
    GUILayout.Width(170));
//...

And same method for your 'Quantity' field.

Make sure InventoryItem not null in your items List.