these is where I'm with my issue.
I've used the angle(x1, y1, x2, y2) / atan function to generate the rotation angle depending on x,y coordinates of the touch action around the piece.
Unfortunately, controls are still impossible to use on mobile, it jumps from one angle to another without distinctions.
I've attached my current test...
Any ideas of the kind of math function I can use ?
I guess there is probably a solution with cosinus using 3 points : x,y and image point - but I don't know how to build it...
Many thanks for you through !