save project

my_tree.py

+import turtle
+import  random
+pen_color=["snow","lightcoral"]
+def tree(n):
+    if  n>=0:
+        if  n<=12:
+            color=random.choice(pen_color)
+            pen.color(color)
+            pen.pensize(n/3)
+        else:
+            pen.color("sienna")
+            pen.pensize(n/10)
+        a=random.random()
+        b=1.5*random.random()
+        pen.forward(n)
+        pen.right(30*a)
+        tree(n-10*b)
+        pen.left(60*a)
+        tree(n-10*b)
+        pen.right(30*a)
+        pen.up()
+        pen.backward(n)
+        pen.down()
+pen = turtle.Turtle()
+pen.color('sienna')
+pen.speed(200)
+# 画布大小
+w = turtle.Screen()
+w.bgcolor('wheat') 
+pen.left(90)
+pen.up()
+pen.backward(150)    # 后退
+pen.down()
+tree(random.randint(60,90))
+turtle.done()
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