The setRotation method is a part of an object transform and is generally applied when drawing to all vertices.

However, you can apply custom transforms (or just calculate manually, for example your rotations) to each vertex manually. Of course, you may no longer need the object transform.

One way to rotate a vertex is by using a

transform. Start with the indentity transform and apply the transformations you wish to apply and then you can use the

transformPoint method.

To rotate a point around another point manually, you will need trigonometric functions. You can google this; it's not too complicated.