code: private static int winding(Point2D a, Point2D b, Point2D c) {
          return (int) Math.signum((b.getX() - a.getX()) * (c.getY() - a.getY()) - (b.getY() - a.getY())
                  * (c.getX() - a.getX()));
      }
docs: Determine the winding of three points. The winding is the sign of the space - the parity.
  
  @param a first point
  @param b second point
  @param c third point
  @return winding, -1=cw, 0=straight, +1=ccw