Brachistochrone/Cycloid simulation

A brachistochrone is the fastest route between two points in an object is thrown from point A to point B in the presence of gravity. It is really cool. There are some fun properties of this Brachistochrone. Vsauce made an awesome video and demonstration on it with Adam Savage.
I think this simulation can me made in p5 and I have attempted to do this on my own. I got some kind of success but not really. You can look at my progress here [https://www.openprocessing.org/sketch/400633](https://www.openprocessing.org/sketch/400633
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I think this would be something cool to do either in p5 or in processing.
Here's a link to the video - [https://www.youtube.com/watch?v=skvnj67YGmw](https://youtu.be/skvnj67YGmw)
Here's a link to the cycloids wiki page - [https://en.wikipedia.org/wiki/Cycloid](https://en.wikipedia.org/wiki/Cycloid)