蝴蝶画树

先新建文本文档
把后缀改为.py
输入以下代码。

from turtle import *
import random
# 设置色彩模式是RGB:
colormode(255)

lt(90)

lv = 14
l = 120
s = 45

width(lv)

# 初始化RGB颜色:
r = 1
g = 100
b = 234
pencolor(r, g, b)

penup()
bk(l)
pendown()
fd(l)

def draw_tree(l, level):
    global r, g, b
    # save the current pen width
    w = width()

    # narrow the pen width
    width(w * 3.0 / 4.0)
    # set color:
    r = r + 1 * random.randint(0,10)
    g = g + 2 * random.randint(0,10)
    b = b + 3 * random.randint(0,10)
    pencolor(r % 200, g % 200, b % 200)

    l = 3.0 / 4.0 * l * random.uniform(0.9,1.1)

    left(s)
    forward(l)

    if level < lv:
        draw_tree(l, level + 1)
    backward(l)
    right(2 * s)
    forward(l)

    if level < lv:
        draw_tree(l, level + 1)
    backward(l)
    left(s)

    # restore the previous pen width
    width(w)

speed(10000)
#speed("fastest")

draw_tree(l, 4)

done()