Retrieve a positive or a negative angle from 3 points

Question

I am rotating points around a center point in 2D space. The points are the center point, the old mouse position, and the new mouse position. My rotation function works fin

Answer 1

It seems like all you need to do is

angle = angle > Math.PI ? angle - 2*Math.PI : angle;

at the end of your code. That will give you a clockwise rotation to the right of the line defined by centerPoint and oldPoint, and counter-clockwise to the left of it, regardless of orientation.