i was kinda trying to create a drawing up just to explore… but i can’t find any tutorial/docs that support pen inputs… so im curious how animation paper does it.
Animation Paper, and other drawing apps, are getting the input through a driver. I am not a programmer, so I am not able to go into details 😉 It should be pretty straight forward though.
In AP we use Qt, so the pen inputs we handle comes in the form of tablet events (https://doc.qt.io/qt-5/qtabletevent.html) which in turn gets input from either a wacom driver, windows ink or possibly some other source depending on hardware and OS.
There are SDKs available to interface directly, but which one to use would depend on your hardware, OS and choice of programming language.