import turtle

from random import random

from random import randint

def draw_petal(turtle_obj, flower):

     # 绘制掉落的花瓣

     for i in range(int(flower)):

         # 有正有负就可以让画笔往二个方向走

         x = flower - 4 * flower * random()

         # 花瓣整体宽度 (-10, 10)

         y = 10 - 20 * random()

         # 提笔，向前 y ，左转 90 ，走 x ，落笔

         turtle_obj.penup()

         turtle_obj.forward(y)

         turtle_obj.left(90)

         turtle_obj.forward(x)

         turtle_obj.pendown()

         # 珊瑚色

         turtle_obj.pencolor("lightcoral")

         # 画圆

         turtle_obj.circle(1)

         # 回到起点

         # 提笔，后退 x ，右转 90, 后退 y ，落笔

         turtle_obj.penup()

         turtle_obj.backward(x)

         turtle_obj.right(90)

         turtle_obj.backward(y)

         turtle_obj.pendown()

# 画树枝部分

def draw_tree(turtle_obj, branch, tree_color):

     # 设置一个最小分支长度

     min_branch = 4

     if branch > min_branch:

         if branch < 8:

             # 以 0.5 的概率，向左、右分支

             if randint(0, 1) == 0:

                 # 左为白色

                 turtle_obj.pencolor("snow")

             else:

                 # 右为珊瑚色

                 turtle_obj.pencolor("lightcoral")

             # 枝干

             turtle_obj.pensize(branch / 2)

         elif 8 <= branch <= 16:

             # 以 0.33 的概率，分为左、中、右分支

             if randint(0, 2) == 0:

                 # 左为白色

                 turtle_obj.pencolor("snow")

             else:

                 # 中、右为珊瑚色

                 turtle_obj.pencolor("lightcoral")

             # 树枝

             turtle_obj.pensize(branch / 4)

         else:

             # 褐色

             turtle_obj.pencolor(tree_color)

             # 细枝

             turtle_obj.pensize(branch / 10)

         # 最开始的树干长度

         turtle_obj.forward(branch)

         # 随机度数因子

         a = 1.5 * random()

         # 顺时针旋转随机角度（ 0 ～ 30 度）

         turtle_obj.right(20 * a)

         # 随机长度因子

         b = 1.5 * random()

         # 往右画，直到画不动为止

         draw_tree(turtle_obj, branch - 10 * b, tree_color)

         # 左转随机角度

         turtle_obj.left(40 * a)

         # 往左画，跟单网gendan5.com直到画不动位置

         draw_tree(turtle_obj, branch - 10 * b, tree_color)

         # 右转一定角度

         turtle_obj.right(20 * a)

         # 提笔

         turtle_obj.penup()

         # 递归结束回到起点

         turtle_obj.backward(branch)

         turtle_obj.pendown()

def get_screen(width, height, color, speed):

     # 创建画幕

     screen_obj = turtle.Screen()

     # 画布大小： (width, height) ，颜色： color

     screen_obj.screensize(width, height, bg=color)

     screen_obj.setup(1.0, 1.0)

     # speed 倍加速

     screen_obj.tracer(speed)

     return screen_obj

def trees(tree_num):

     # 颜色

     color = ['brown', 'tan', 'black']

     for j in range(tree_num):

         # 树干颜色

         tree_color = color[randint(0, len(color) - 1)]

         # 画笔大小

         pensize = randint(2, 5)

         # 前进像素

         forward = ((-1) ** pensize) * pensize * randint(20, 50)

         # 后退像素

         if pensize <= 3:

             backward = ((-1) ** pensize) * (5 - pensize) * randint(10, 15)

         else:

             backward = pensize * randint(45, 50)

         # 创建画笔

         turtle_obj = turtle.Turtle()

         # 画笔粗细

         turtle_obj.pensize(pensize)

         # 提笔，向前 forward ，左转 90 ， backward ，落笔

         turtle_obj.penup()

         turtle_obj.forward(forward)

         turtle_obj.left(90)

         turtle_obj.backward(backward)

         turtle_obj.pendown()

         # 画笔颜色：褐色

         turtle_obj.pencolor(tree_color)

         # 枝干粗细

         branch = pensize * 15

         # 落花数

         flowers = branch

         # 第 j 棵树

         draw_tree(turtle_obj, branch, tree_color)

         # 花瓣

         draw_petal(turtle_obj, flowers)

if __name__ == '__main__':

     # 创建画幕

     my_screen_width = 800

     my_screen_height = 600

     my_screen_color = 'wheat'

     my_screen_speed = 5

     my_screen_obj = get_screen(my_screen_width, my_screen_height,

                                my_screen_color, my_screen_speed,)

     # 樱花树

     # 棵数

     my_tree_num = 10

     trees(my_tree_num)

     # 点击关闭画布

     my_screen_obj.exitonclick()