Pinwheel rotates the points of a star, causing the overall shape to resemble a pinwheel or turbine, as illustrated in the following diagram:
Pinwheel is normalized such that at 1, each "tooth" has one of its edges (the "cutting" edge) positioned on a line that passes through the center. At −1, the teeth face clockwise instead of counterclockwise. At zero, Pinwheel has no effect.
Pinwheel is typically used in combination with Star Factor, but it has an effect even when Star Factor is zero. Pinwheel's range is twice the ring's number of sides, i.e. for a six-sided ring, Pinwheel = 6 is the most extreme value, and Pinwheel = 12 is the same as Pinwheel = 0. Extreme values cause the ring to overlap itself in interesting ways, but may also reduce performance.