self.increment = coord(-math.sin(self.angle), math.cos(self.angle))
bigger = max(abs(self.increment.i), abs(self.increment.j))
self.increment /= bigger
self.increment = coord(-math.sin(self.angle), math.cos(self.angle))
bigger = max(abs(self.increment.i), abs(self.increment.j))
self.increment /= bigger