让球在基于Python的乒乓球游戏中移动

Question

这个程序是一个简单的单人乒乓球游戏。它包括桨，一个球和球会击中的块。当我运行程序时，一切都会出现，我的桨将会右移和左移，但乒乓球根本不会移动。我无法弄清楚为什么。任何帮助将非常感激..

import tkinter 

class Game(Frame): 
    def __init__(self, master): 
     super(Game, self).__init__(master) 
     self.lives = 3 
     self.width = 610 
     self.height = 400 
     self.canvas = Canvas(self, bg='#aaaaff', 
           width=self.width, 
           height=self.height) 
     self.canvas.pack() 
     self.pack() 

     self.items = {} 
     self.ball = None 
     self.paddle = Paddle(self.canvas, self.width/2, 326) 
     self.items[self.paddle.item] = self.paddle 
     for x in range(5, self.width - 5, 75): 
      self.add_brick(x + 37.5, 50, 2) 
      self.add_brick(x + 37.5, 70, 1) 
      self.add_brick(x + 37.5, 90, 1) 

     self.hud = None 
     self.setup_game() 
     self.canvas.focus_set() 
     self.canvas.bind('<Left>', 
         lambda _: self.paddle.move(-10)) 
     self.canvas.bind('<Right>', 
         lambda _: self.paddle.move(10)) 

    def setup_game(self): 
      self.add_ball() 
      self.update_lives_text() 
      self.text = self.draw_text(300, 200, 
      'Press Space to start') 
      self.canvas.bind('<space>', 
      lambda _: self.start_game()) 
    def add_ball(self): 
     if self.ball is not None: 
      self.ball.delete() 
     paddle_coords = self.paddle.get_position() 
     x = (paddle_coords[0] + paddle_coords[2]) * 0.5 
     self.ball = Ball(self.canvas, x, 310) 
     self.paddle.set_ball(self.ball) 

    def add_brick(self, x, y, hits): 
     brick = Brick(self.canvas, x, y, hits) 
     self.items[brick.item] = brick 

    def draw_text(self, x, y, text, size='40'): 
     font = ('Helvetica', size) 
     return self.canvas.create_text(x, y, text=text, 
             font=font) 


    def update_lives_text(self): 
     text = 'Lives: %s' % self.lives 
     if self.hud is None: 
      self.hud = self.draw_text(50, 20, text, 15) 
     else: 
      self.canvas.itemconfig(self.hud, text=text) 


    def check_collisions(self): 
     ball_coords = self.ball.get_position() 
     items = self.canvas.find_overlapping(*ball_coords) 
     objects = [self.items[x] for x in items \ 
       if x in self.items] 
     self.ball.collide(objects) 


    def update(self): 
     coords = self.get_position() 
     width = self.canvas.winfo_width() 
     if coords[0] <= 0 or coords[2] >= width: 
      self.direction[0] *= -1 
     if coords[1] <= 0: 
      self.direction[1] *= -1 
     x = self.direction[0] * self.speed 
     y = self.direction[1] * self.speed 
     self.move(x, y) 


    def start_game(self): 
     self.canvas.unbind('<space>') 
     self.canvas.delete(self.text) 
     self.paddle.ball = None 
     self.game_loop() 

    def game_loop(self): 
     self.check_collisions() 
     num_bricks = len(self.canvas.find_withtag('brick')) 
     if num_bricks == 0: 
      self.ball.speed = None 
      self.draw_text(300, 200, 'You win!') 
     elif self.ball.get_position()[3] >= self.height: 
      self.ball.speed = None 
      self.lives -= 1 
      if self.lives < 0: 
       self.draw_text(300, 200, 'Game Over') 
      else: 
       self.after(1000, self.setup_game) 
     else: 
      self.ball.update() 
      self.after(50, self.game_loop) 

    def collide(self, game_objects): 
     coords = self.get_position() 
     x = (coords[0] + coords[2]) * 0.5 
     if len(game_objects) > 1: 
      self.direction[1] *= -1 
     elif len(game_objects) == 1: 
      game_object = game_objects[0] 
      coords = game_object.get_position() 
      if x > coords[2]: 
       self.direction[0] = 1 
      elif x < coords[0]: 
       self.direction[0] = -1 
      else: 
       self.direction[1] *= -1 

     for game_object in game_objects: 
      if isinstance(game_object, Brick): 
       game_object.hit() 

class GameObject(object): 
    def __init__(self, canvas, item): 
     self.canvas = canvas 
     self.item = item 

    def get_position(self): 
     return self.canvas.coords(self.item) 

    def move(self, x, y): 
     self.canvas.move(self.item, x, y) 

    def delete(self): 
     self.canvas.delete(self.item)  


class Ball(GameObject): 
    def __init__(self, canvas, x, y): 
     self.radius = 10 
     self.direction = [1, -1] 
     self.speed = 10 
     item = canvas.create_oval(x-self.radius, y-self.radius, 
            x+self.radius, y+self.radius, 
            fill='white') 
     super(Ball, self).__init__(canvas, item) 

class Paddle(GameObject): 
    def __init__(self, canvas, x, y): 
     self.width = 80 
     self.height = 10 
     self.ball = None 
     item = canvas.create_rectangle(x - self.width/2, 
             y - self.height/2, 
             x + self.width/2, 
             y + self.height/2, 
             fill='blue') 
     super(Paddle, self).__init__(canvas, item) 

    def set_ball(self, ball): 
     self.ball = ball 

    def move(self, offset): 
     coords = self.get_position() 
     width = self.canvas.winfo_width() 
     if coords[0] + offset >= 0 and \ 
      coords[2] + offset <= width: 
      super(Paddle, self).move(offset, 0) 
      if self.ball is not None: 
       self.ball.move(offset, 0) 

class Brick(GameObject): 
    COLORS = {1: '#999999', 2: '#555555', 3: '#222222'} 

    def __init__(self, canvas, x, y, hits): 
     self.width = 75 
     self.height = 20 
     self.hits = hits 
     color = Brick.COLORS[hits] 
     item = canvas.create_rectangle(x - self.width/2, 
             y - self.height/2, 
             x + self.width/2, 
             y + self.height/2, 
             fill=color, tags='brick') 
     super(Brick, self).__init__(canvas, item) 

    def hit(self): 
     self.hits -= 1 
     if self.hits == 0: 
      self.delete() 
     else: 
      self.canvas.itemconfig(self.item, 
            fill=Brick.COLORS[self.hits]) 

if __name__ == '__main__': 
    root = tkinter.Tk() 
    root.title('Pong Game') 
    game = Game(root) 
    game.mainloop() 

Answer 1

的Ball类没有你在game_loop方法调用更新方法。只需加上：

def update(self): 
    # Only moves upwards. You still have to figure out how to change the direction. 
    self.move(0, -4)