save project

my_tree.py

+import turtle
+import random
+pen = turtle.Turtle()
+pen.hideturtle()
+pen.color('sienna')
+# 画布大小
+w = turtle.Screen()
+w.bgcolor('wheat')      # wheat小麦
+# 移动到起点
+pen.left(90)#让树保留在画布的正上方
+pen.up()
+pen.backward(150)    # 后退
+pen.down()
+def tree(n):    #画树枝。利用递归
+    if n>=0:    #n：树枝长度。
+        if n<=12:
+            color_list=["snow","red"]#颜色
+            color=random.choice(color_list)
+            pen.color(color)
+            pen.pensize(n/3)#笔的大小
+        else:
+            pen.pensize(n/10)
+            pen.color('sienna')
+        pen.forward(n)
+        angle=random.randint(0,30)
+        length=random.randint(1,15)
+        pen.right(angle)#角度
+        tree(n-length)#调用函数
+        pen.left(2*angle)
+        tree(n-length)
+        pen.right(angle)
+        pen.up()
+        pen.backward(n)
+        pen.down()
+tree(60)
+turtle.done()