CyrusBeck线裁剪算法

Question

我试图实现Cyrus-Beck algorithm来进行线条裁剪。但它不起作用。我找不到问题。。。请帮忙。在

结构：

sign = functools.partial(math.copysign, 1)
mult = lambda a, b: a.x * b.x + a.y * b.y


class Point(object):
    def __init__(self, x, y):
        self.x = float(x)
        self.y = float(y)


class Line(object):
    def __init__(self, begin, end):
        self.begin = begin
        self.end = end

    @property
    def direction(self):
        return Point(self.end.x - self.begin.x, self.end.y - self.begin.y)

    @property
    def normal(self):
        return Point(self.end.y - self.begin.y, self.begin.x - self.end.x)

这是算法和class Polygon

^{pr2}$

帮我找出代码中的错误。在