The old tree was falling apart so I bought a prelit tree because it was RGB, meaning the lights can be any colour.
I had no idea the lights could do what they do until they did it and my mind was blown!
The app uses the camera to map the position of each light individually. Then the app knows exactly where the lights are on the tree to create the effects.
https://www.youtube.com/watch?v=4-VwLj05GQ8
They were on Kickstarter in 2016. Now they're in the stores.