python 利用turtle库绘制五角星

# -*- coding: utf-8 –*-
import turtle
import math

def draw_polygon(aTurtle, size=50, n=3):
for i in range(n):
aTurtle.forward(size)
aTurtle.left(360.0/n)

def draw_n_angle(aTurtle, size=50, num=5, color=None):
if color:
aTurtle.begin_fill()
aTurtle.fillcolor(color)
for i in range(num):
aTurtle.forward(size)
aTurtle.left(360.0/num)
aTurtle.forward(size)
aTurtle.right(2*360.0/num)
if color:
aTurtle.end_fill()

def draw_5_angle(aTurtle=None, start_pos=(0,0), end_pos=(0,10), radius=100, color=None):
aTurtle = aTurtle or turtle.Turtle()
size = radius * math.sin(math.pi/5)/math.sin(math.pi*2/5)
aTurtle.pencolor('yellow')
aTurtle.left(math.degrees(math.atan2(end_pos[1]-start_pos[1], end_pos[0]-start_pos[0])))
aTurtle.penup()
aTurtle.goto(start_pos)
aTurtle.fd(radius)
aTurtle.pendown()
aTurtle.right(math.degrees(math.pi*9/10))
draw_n_angle(aTurtle, size, 5, color)

def draw_5_star_flag(times=20.0):
width, height = 30*times, 20*times
window = turtle.Screen()
aTurtle = turtle.Turtle()
aTurtle.hideturtle()
aTurtle.speed(10)

# 画五星
draw_5_angle(aTurtle, start_pos=(-10*times, 5*times), end_pos=(-10*times, 8*times), radius=3*times, color='red')

# 点击关闭窗口
window.exitonclick()

if __name__ == '__main__':
draw_5_star_flag()

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