地球绕着太阳转月亮绕着地球转.py

"""地球绕着太阳转月亮绕着地球转.py"""
__author__ = "李兴球"
__date__ = "2018年5月"

import pygame
from pygame.locals import *
import math

pygame.init()
screenWidth,screenHeight=480,360
screenCenterx = screenWidth//2 -1
screenCentery = screenHeight//2 -1
screen = pygame.display.set_mode((screenWidth,screenHeight))
pygame.display.set_caption("太阳系公转,地月系_地球绕着太阳转月亮绕着地球转_作者:李兴球")

class Ball():
    def __init__(self,r,color,speed):
        """球的半径,颜色和每次转的角速度"""
        self.image = pygame.Surface((2*r,2*r))
        pygame.draw.circle(self.image,color,(r,r),r)
        self.image.set_colorkey((0,0,0))
        self.rect = self.image.get_rect()
        self.speed= speed
        self.angle = 0
    def move(self,x,y,radius):
        """绕着x,y点以radius为半径旋转"""
        self.rect.centerx = x + radius * math.cos(math.radians(self.angle))
        self.rect.centery = y + radius * math.sin(math.radians(self.angle))
        self.angle = self.angle + self.speed
    def draw(self):
        screen.blit(self.image,self.rect)        

def main():
    earth = Ball(20,(0,0,255),1)
    moon = Ball(10,(255,255,200),5)
    clock = pygame.time.Clock()
    运行中 = True
    while 运行中:
        for event in pygame.event.get():
            if event.type==QUIT:运行中 =False
        screen.fill((0,0,0))
        #画个太阳在中间
        pygame.draw.circle(screen,(255,11,0),(screenCenterx,screenCentery),40)
        earth.move(screenCenterx,screenCentery,150)
        earth.draw()
        moon.move(earth.rect.centerx,earth.rect.centery,50)
        moon.draw()
        pygame.display.flip()
        clock.tick(60)

    pygame.quit()

if __name__ == "__main__":
    main()