python 求直线交点坐标

# -*- coding: utf-8 -*-
class Point(object):
    x =0
    y= 0
    # 定义构造方法
    def __init__(self, x=0, y=0):
        self.x = x
        self.y = y

class Line(object):
    # a=0
    # b=0
    # c=0
    def __init__(self, p1, p2):
        self.p1 = p1
        self.p2 = p2


def GetLinePara(line):
    line.a =line.p1.y - line.p2.y;
    line.b = line.p2.x - line.p1.x;
    line.c = line.p1.x *line.p2.y - line.p2.x * line.p1.y;


def GetCrossPoint(l1,l2):

    GetLinePara(l1);
    GetLinePara(l2);
    d = l1.a * l2.b - l2.a * l1.b
    p=Point()
    p.x = (l1.b * l2.c - l2.b * l1.c)*1.0 / d
    p.y = (l1.c * l2.a - l2.c * l1.a)*1.0 / d
    return p;



p1=Point(1,1)
p2=Point(3,3)
line1=Line(p1,p2)

p3=Point(2,3.1)
p4=Point(3.1,2)
line2=Line(p3,p4)
Pc = GetCrossPoint(line1,line2);
print("Cross point:", Pc.x, Pc.y);