geometry – How can I implement an aiming system like the Tank Stars mobile game?

I have been trying to implement the same aiming system as in Tank Stars, but I got a little stuck. I implemented simple stick aiming, which basically aims towards the stick movement.

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In Tank Stars, it is much different compared to the simple aim stick. It remembers the last position and uses it as something like a pivot point.


I tried to implement a virtual pivot point as in the image given. The red circle is a virtual pivot. The green circle is the stick center point, and the green arrow is the supposed stick movement. This implementation kind of works, but I don’t understand how I should update that pivot point.

Is my approach correct? What is the name of this aiming system? I need a bit of help with the math behind it.