Editor-only function that Unity calls when the script is loaded or a value changes in the Inspector.
Use this to perform an action after a value changes in the Inspector; for example, making sure that data stays within a certain range.
Note: You should not use this callback to do other tasks such as create objects or call other non-thread-safe Unity API. You should only use it to validate the data that changed. This restriction is because OnValidate can be be called often when the user interacts with an inspector in the Editor, and because OnValidate can be called from threads other than Unity's main thread, such as the loading thread.
Note: You cannot reliably perform Camera rendering operations here. Instead, you should add a listener to EditorApplication.update, and perform the rendering during the next Editor Update call.