def _rotate_vector(x, y, x2, y2, x1, y1):
        """
        rotate x,y vector over x2-x1, y2-y1 angle
        """
        angle = atan2(y2 - y1, x2 - x1)
        cos_rad = cos(angle)
        sin_rad = sin(angle)
        return cos_rad * x + sin_rad * y, -sin_rad * x + cos_rad * y
def _rotate_vector ( x , y , x2 , y2 , x1 , y1 ) : angle = atan2 ( y2 - y1 , x2 - x1 ) cos_rad = cos ( angle ) sin_rad = sin ( angle ) return cos_rad * x + sin_rad * y , - sin_rad * x + cos_rad * y
rotate x,y vector over x2-x1, y2-y1 angle