绘制分形树

递归方法绘制一颗分形树。

# coding=gbk
'''
    分形树的绘制

'''
import turtle


def tree(length):

    if length > 5:  # 递归终止条件
        turtle.fd(length)
        turtle.right(20)
        tree(length - 15)

        turtle.left(40)
        tree(length - 15)

        turtle.right(20)
        turtle.bk(length)


def main():
    turtle.penup()
    turtle.bk(80)
    turtle.pendown()
    turtle.pensize(3)
    turtle.pencolor('red')
    turtle.left(90)
    tree(80)
    turtle.exitonclick()


if __name__ == '__main__':
    main()