PI

A Number constant that's approximately 3.1416.

PI is the mathematical constant π. It's useful for many tasks that involve rotation and oscillation. For example, calling rotate(PI) rotates the coordinate system PI radians, which is a half turn (180˚).

Note: TWO_PI radians equals 360˚, PI radians equals 180˚, HALF_PI radians equals 90˚, and QUARTER_PI radians equals 45˚.