Python精灵模块的scale_points指令

import time
from sprites import Sprite,scale_points

def draw_polygon(g,points):
    """用角色g连接points中的中点画多边形"""
    g.goto(points[0]);g.pendown()
    for p in points[1:]:g.goto(p)
    g.goto(points[0]);g.penup()
    
A = (-50,-50);B=(50,-50);C=(0,50)
ps = [A,B,C]

pen = Sprite('blank')
pen.screen.bgcolor('black')
pen.color('yellow')
pen.width(10)
while True:
    for i in range(1,11):
        pen.clear()
        # 在水平和垂直方向上缩放x,y坐标
        ps2 = scale_points(ps,1+i*0.1,1+i*0.1)
        draw_polygon(pen,ps2)
        time.sleep(0.01)
    for i in range(10,0,-1):
        pen.clear()
        ps2 = scale_points(ps,i/10,i/10)
        draw_polygon(pen,ps2)
        time.sleep(0.01)