ShowOnlyDrawer

using UnityEditor;
using UnityEngine;

[CustomPropertyDrawer(typeof(ShowOnlyAttribute))]

public class ShowOnlyDrawer : PropertyDrawer {
    public override void OnGUI(Rect position, SerializedProperty prop, GUIContent label) {
        string valueStr;

        switch (prop.propertyType)
        {
        case SerializedPropertyType.Vector2:
            valueStr = prop.vector2Value.ToString();
            break;
        case SerializedPropertyType.Vector3:
            valueStr = prop.vector3Value.ToString();
            break;
        case SerializedPropertyType.Vector4:
            valueStr = prop.vector4Value.ToString();
            break;
        case SerializedPropertyType.Integer:
            valueStr = prop.intValue.ToString();
            break;
        case SerializedPropertyType.Boolean:
            valueStr = prop.boolValue.ToString();
            break;
        case SerializedPropertyType.Float:
            valueStr = prop.floatValue.ToString("0.00000");
            break;
        case SerializedPropertyType.String:
            valueStr = prop.stringValue;
            break;
        case SerializedPropertyType.Enum:
            valueStr = prop.enumDisplayNames[prop.enumValueIndex];
            break;
        case SerializedPropertyType.Rect:
            valueStr = prop.rectValue.ToString ();
            break;
        case SerializedPropertyType.ObjectReference:
            if (prop.objectReferenceValue != null)
                valueStr = prop.objectReferenceValue.name;
            else
                valueStr = "Null";
            break;
        case SerializedPropertyType.ArraySize:
            valueStr = prop.arraySize.ToString();
            break;
        default:
            valueStr = "Not supported";
            break;
        }

        EditorGUI.LabelField(position, label.text, valueStr);
    }
}