trail-into-darkness/Packages/com.jovian.inspector/Editor/Attributes/ReadOnlyAttribute.cs

using UnityEngine;

namespace Jovian.InspectorTools
{
    public class ReadOnlyAttribute : ConditionalFieldAttribute
    {
        public ReadOnlyAttribute() : base("") { }

        /// <param name="fieldToCheck">String name of field to check value</param>
        /// <param name="inverse">Inverse check result</param>
        /// <param name="compareValues">On which values field will be shown in inspector</param>
        public ReadOnlyAttribute(string fieldToCheck, bool inverse = false, params object[] compareValues)
            : base(fieldToCheck, inverse, compareValues) { }
    }
}

#if UNITY_EDITOR
namespace Jovian.InspectorTools.Internal
{
    using UnityEditor;

    [CustomPropertyDrawer(typeof(ReadOnlyAttribute))]
    public class ReadOnlyAttributeDrawer : PropertyDrawer
    {
        public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
        {
            return EditorGUI.GetPropertyHeight(property, label, true);
        }

        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
        {
            if (!(attribute is ReadOnlyAttribute conditional)) return;

            bool enabled = false;

            if (!string.IsNullOrEmpty(conditional.FieldToCheck))
            {
                var propertyToCheck = ConditionalFieldUtility.FindRelativeProperty(property, conditional.FieldToCheck);
                enabled = !ConditionalFieldUtility.PropertyIsVisible(propertyToCheck, conditional.Inverse, conditional.CompareValues);
            }

            GUI.enabled = enabled;
            EditorGUI.PropertyField(position, property, label, true);
            GUI.enabled = true;
        }
    }
}
#endif