cosine polyline

def cosine_polyline(pdf, x0, y0, x1, y1, orientation):
    N = 32
    x_points = []
    y_points = []
    if orientation == horizontal:
        w = (x1 - x0)
        h = 0.5 * (y1 - y0)
        y_avg = 0.5 * (y0 + y1)
    elif orientation == vertical:
        w = 0.5 * (x1 - x0)
        h = (y1 - y0)
        x_avg = 0.5 * (x0 + x1)
    else:
        raise Exception()

    for i in range(0, N + 1):
        frac = float(i) / N
        angle = math.pi * frac
        if orientation == horizontal:
            x = x0 + w * frac
            y = y_avg + h * math.cos(angle)
        elif orientation == vertical:
            x = x_avg - w * math.cos(angle)
            y = y0 + h * frac
        else:
            raise Exception()

        x_points.append(x)
        y_points.append(y)

    pdf.draw_polyline(x_points, y_points)