printer.py 文件源码

def compute_circle_intersection(x0, y0, x1, y1, r0, r1):
    d = compute_distance(x0, y0, x1, y1)
    if d < math.fabs(r0 - r1) or r0 +r1 < d:
        return None

    a = (math.pow(r0, 2) - math.pow(r1, 2) + math.pow(d, 2))/float(2 * d)
    h = math.sqrt(math.pow(r0, 2) - math.pow(a, 2))

    x2 = x0 + a * (x1 - x0)/float(d)
    y2 = y0 + a * (y1 - y0)/float(d)

    x3 = x2 + h * (y1 - y0)/ d
    y3 = y2 - h * (x1 - x0)/ d

    x3_prime = x2 - h * (y1 - y0)/ d
    y3_prime = y2 + h * (x1 - x0)/ d
    return (x3, y3), (x3_prime, y3_prime)