Im drawing a system using control systems engineering. It changes over time and many factors affect each other. So far I've been using draw.io for drawing program architecture and it works great but Im looking for something more directed at flowcharts/control systems. Requirements: >Layers, Ability to draw many pathways, ability to hide different layers or show all. >time windows. Here, sheets would be enough, but I want to be able to show how the system changes over time. >Different colors >FREE. I am a mere student with no income. >Able to save my progress Non-requirements: >I dont need control system calculations, I can already use simulink for that, but ofcourse it wouldn't hurt. >Stand alone application, it's ok if it's in browser but ofc I prefer an app.