code: function ccw (ax, ay, bx, by, cx, cy) {
    var raw = ccwRaw(ax, ay, bx, by, cx, cy)
    return (raw === 0) ? 0 : raw / Math.abs(raw)
  }
docs: /*
  CCW utility function. Accepts 3 coord pairs; result is positive if points
  have counterclockwise orientation, negative if clockwise, 0 if collinear.