Sprite不会在pygame中移动

Question

此代码中的“行星”精灵不会左右移动，不会动画。错误在哪里？实际上，该列表来自 google play 的应用程序“Programming Hero”，其中应用程序的作者一步一步地指导学生完成视频 - 使用 python 制作游戏的过程......import pygamescreen_size = [360,640]screen =     pygame.display.set_mode(screen_size)background = pygame.image.load('background.png')planet =     pygame.image.load('one.png')spaceship =  pygame.image.load('spaceship.png')bullet =     pygame.image.load('bullet.png')keep_alive = Trueplanet_x = 140           # I've edited thismove_direction = 'right' # out of the loop, too# according to the same logic "I've saved the planet" to go infinitely right# thanx while keep_alive:    pygame.event.get()    keys = pygame.key.get_pressed()    if keys[pygame.K_SPACE] == True:        print('Space key pressed')    screen.blit(background, [0,0])    screen.blit(bullet,[180,500])    screen.blit(spaceship,[160,500])    # I put this out off loop:           planet_x = 140    # wrong, must go out of a loop, too: move_direction = 'right'    if move_direction == 'right':        planet_x = planet_x + 5        if planet_x == 270:            move_direction = 'left'    else:        planet_x = planet_x - 5        if planet_x == 0:            move_direction = 'right'    screen.blit(planet, [planet_x, 50])    pygame.display.update()

Answer 1

行星 ( planet_x) 的位置在每一帧中重新初始化：

while keep_alive:

   # [...]

   planet_x = 140

   if move_direction == 'right':

       planet_x = planet_x + 5

   # [...]

   screen.blit(planet, [planet_x, 50])

将 , 的初始化移到planet_x主应用程序循环之前：

planet_x = 140

while keep_alive:

    # [...]

    if move_direction == 'right':

        planet_x = planet_x + 5

    # [...]

    screen.blit(planet, [planet_x, 50])