用Python的Turtle模块绘制五星红旗

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用Python的Turtle模块绘制五星红旗

在Udacity上课时学到了python的turtle方法,这是一个很经典的用来教小孩儿编程的图形模块,最早起源于logo语言。python本身内置了这个模块,其可视化的方法可以帮助小孩儿对编程的一些基本理念有所理解。
在作业提交的论坛里看到很多turtle画出来的精美图形,想不出什么要画的东西,于是决定拿五星红旗来练练手。

前期准备

  • 五星红旗绘制参数
  • Turtle官方文档

turtle的基本操作

# 初始化屏幕
window = turtle.Screen()
# 新建turtle对象实例
import turtle
aTurtle = turtle.Turtle()
# 海龟设置
aTurtle.hideturtle()    # 隐藏箭头
aTurtle.speed(10)       # 设置速度
# 前进后退,左转右转
aTurtle.fd(100)     # 前进100像素
aTurtle.right(90)   # 右转90°
aTurtle.back(100)
aTurtle.left(90)
# 填充颜色
aTurtle.begin_fill()
aTurtle.fillcolor('yellow')
DoSomethinghere()
aTurtle.end_fill()
# 抬起笔和放下笔,这样进行的操作不会留下痕迹
aTurtle.penup()
aTurtle.goto(start_pos)
aTurtle.fd(radius)
aTurtle.pendown()

绘制五星红旗代码

github地址:https://gist.github.com/dc11287081ee67075da8

#!/usr/bin/env python     
# -*- coding: utf-8 –*-
''' 对于turtle类的一些封装方法,包括画正多边形,正多角形和五星红旗。'''
__author__ = 'Hu Wenchao'

import turtle
import math

def draw_polygon(aTurtle, size=50, n=3):
    ''' 绘制正多边形

    args:
        aTurtle: turtle对象实例
        size: int类型,正多边形的边长
        n: int类型,是几边形        
    '''
    for i in xrange(n):
        aTurtle.forward(size)
        aTurtle.left(360.0/n)

def draw_n_angle(aTurtle, size=50, num=5, color=None):
    ''' 绘制正n角形,默认为黄色

    args:
        aTurtle: turtle对象实例
        size: int类型,正多角形的边长
        n: int类型,是几角形    
        color: str, 图形颜色,默认不填色
    '''
    if color:
        aTurtle.begin_fill()
        aTurtle.fillcolor(color)
    for i in xrange(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):
    ''' 根据起始位置、结束位置和外接圆半径画五角星

    args:
        aTurtle: turtle对象实例
        start_pos: int的二元tuple,要画的五角星的外接圆圆心
        end_pos: int的二元tuple,圆心指向的位置坐标点
        radius: 五角星外接圆半径
        color: str, 图形颜色,默认不填色    
    '''
    aTurtle = aTurtle or turtle.Turtle()
    size = radius * math.sin(math.pi/5)/math.sin(math.pi*2/5)
    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):
    ''' 绘制五星红旗

    args:
        times: 五星红旗的规格为30*20, times为倍数,默认大小为10倍, 即300*200
    '''
    width, height = 30*times, 20*times
    # 初始化屏幕和海龟
    window = turtle.Screen()
    aTurtle = turtle.Turtle()
    aTurtle.hideturtle()
    aTurtle.speed(10)
    # 画红旗
    aTurtle.penup()
    aTurtle.goto(-width/2, height/2)
    aTurtle.pendown()
    aTurtle.begin_fill()
    aTurtle.fillcolor('red')
    aTurtle.fd(width)
    aTurtle.right(90)
    aTurtle.fd(height)
    aTurtle.right(90)
    aTurtle.fd(width)
    aTurtle.right(90)
    aTurtle.fd(height)
    aTurtle.right(90)    
    aTurtle.end_fill()
    # 画大星星
    draw_5_angle(aTurtle, start_pos=(-10*times, 5*times), end_pos=(-10*times, 8*times), radius=3*times, color='yellow')  
    # 画四个小星星
    stars_start_pos = [(-5, 8), (-3, 6), (-3, 3), (-5, 1)]
    for pos in stars_start_pos:
        draw_5_angle(aTurtle, start_pos=(pos[0]*times, pos[1]*times), end_pos=(-10*times, 5*times), radius=1*times, color='yellow')  
    # 点击关闭窗口
    window.exitonclick()

if __name__ == '__main__':
        draw_5_star_flag()

效果图

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