Python3使用turtle模块和while循环绘制多角星的代码问题咨询

问题原因分析 #

• 后续星星无法绘制：计数变量x在绘制完第一颗星星后未重置为0，且角度计算变量A、B仅在首次绘制前计算，后续更换角数后没有更新对应角度，导致循环不执行或绘制角度错误。
• 填充仅覆盖角：begin_fill()和end_fill()被放在循环内部，每画一个角就单独执行一次填充，自然只能填充单个角而非整体。

修正后代码 #

from turtle import *

def start():
    """This function initializes the window and the turtle.
    Do not modify this function.
    """
    setup(564, 564)
    width(7)
    side_length = 60 # Also the radius of a circle enclosed by the star.
    penup()
    goto(0, -side_length) # Start at the bottom of the star.
    pendown()

def draw_star(points, line_color, fill_color, pos_x, pos_y, side_length=60):
    # 移动到指定绘制位置
    penup()
    goto(pos_x, pos_y)
    pendown()
    # 重置海龟朝向，避免上一次绘制的角度残留
    setheading(0)
    # 计算当前星星的对应角度
    A = 360 / points
    B = 2 * A
    x = 0
    # 设置颜色，整颗星星只执行一次开始填充
    color(line_color, fill_color)
    begin_fill()
    while x < points:
        left(A)
        forward(side_length)
        right(B)
        forward(side_length)
        x += 1
    # 整颗星星绘制完成后再结束填充
    end_fill()

def main():
    side_length = 60
    # 绘制第一颗星星
    points = int(input('How many points would you like on your star? '))
    draw_star(points, 'blue', 'red', 0, -side_length)
    # 绘制第二颗星星
    points = int(input('How many points would you like on your star? '))
    draw_star(points, 'green', 'yellow', 2*side_length, 2*side_length)
    # 绘制第三颗星星
    points = int(input('How many points would you like on your star? '))
    draw_star(points, 'orange', 'purple', -2*side_length, 2*side_length)

# Do not change anything after this line.
if __name__ == '__main__':
    start()
    main()
    done()

优化说明 #

将重复的星星绘制逻辑封装为独立函数，每次绘制前自动重置计数变量、角度参数和海龟朝向，避免重复代码的同时也避免了变量复用导致的逻辑错误。填充逻辑调整为整颗星星绘制前后各执行一次，即可实现整体填充效果。

内容的提问来源于stack exchange，提问作者Skantrow