I think I already got the idea of the Entity System inspired by Adam Martin (t-machine). I want to start using this for my next project.
I already know the basic of Entity, Components, and Systems. My problem is how to handle UI / HUD. For example, a quest window, skill window, character info window, etc. How do you handle UI events (eg. pressing a button)? These are stuff that doesn't need to be processed every frame. Currently, I'm using MVC to code UI but I don't think that'll be compatible for Entity System.
I've read that Entity System is embedded on a larger OOP. I don't know if UI is outside of ES or not. How do I approach this one?