save project

my_tree.py

 import turtle
+import random
 
 pen = turtle.Turtle()
 pen.color('sienna')
@@ -12,14 +13,19 @@ pen.up()
 pen.backward(150)    # 后退
 pen.down()
 
-pen.forward(100)
-pen.right(30)
-pen.forward(50)
-pen.penup()
-pen.backward(50)
-pen.pendown()
-pen.left(60)
-pen.forward(50)
-
+def tree(n):
+    if n>=20:
+        angle=random.randint(10,30)
+        length=random.randint(10,15)
+        pen.forward(n)
+        pen.right(angle)
+        tree(n-length)
+        pen.left(angle*2)
+        tree(n-length)
+        pen.right(angle)
+        pen.penup()
+        pen.forward(-n)
+        pen.pendown()
 
+tree(100)
 turtle.done()