如何在屏幕上显示游戏？

Question

我想用启动菜单制作一个kivy应用程序，但是我无法在第二个屏幕上显示我的乒乓游戏。我应该如何参考游戏使其可见？我试过并搜索过但找不到任何东西。我100％确定PongGame正常工作，我无法显示它。如果有人能告诉我如何正确地做到这一点，那将是非常棒的。

Main.py：

from kivy.app import App 
from kivy.uix.screenmanager import ScreenManager, Screen, WipeTransition 
from kivy.properties import ObjectProperty 
from kivy.uix.widget import Widget 
from kivy.properties import NumericProperty, ReferenceListProperty,\ 
    ObjectProperty 
from kivy.vector import Vector 
from kivy.clock import Clock 
from kivy.uix.popup import Popup 
from kivy.uix.label import Label 

class PongPaddle(Widget): 
    score = NumericProperty(0) 

    def bounce_ball(self, ball): 
     if self.collide_widget(ball): 
      vx, vy = ball.velocity 
      offset = (ball.center_y - self.center_y)/(self.height/2) 
      bounced = Vector(-1 * vx, vy) 
      vel = bounced * 1.1 
      ball.velocity = vel.x, vel.y + offset 


class PongBall(Widget): 
    velocity_x = NumericProperty(0) 
    velocity_y = NumericProperty(0) 
    velocity = ReferenceListProperty(velocity_x, velocity_y) 

    def move(self): 
     self.pos = Vector(*self.velocity) + self.pos 


class PongGame(Widget): 
    ball = ObjectProperty(None) 
    player1 = ObjectProperty(None) 
    player2 = ObjectProperty(None) 

    def serve_ball(self, vel=(4, 0)): 
     self.ball.center = self.center 
     self.ball.velocity = vel 

    def update(self, dt): 
     self.ball.move() 

     #bounce of paddles 
     self.player1.bounce_ball(self.ball) 
     self.player2.bounce_ball(self.ball) 

     #bounce ball off bottom or top 
     if (self.ball.y < self.y) or (self.ball.top > self.top): 
      self.ball.velocity_y *= -1 

     #went of to a side to score point? 
     if self.ball.x < self.x: 
      self.player2.score += 1 
      self.serve_ball(vel=(4, 0)) 

     if self.ball.x > self.width: 
      self.player1.score += 1 
      self.serve_ball(vel=(-4, 0)) 
      if self.player1.score == 10: 
       popup = Popup(title='Test popup', content=Label(text='Hello world'), auto_dismiss=False) 
       return popup 
    def on_touch_move(self, touch): 
     if touch.x < self.width/3: 
      self.player1.center_y = touch.y 
     if touch.x > self.width - self.width/3: 
      self.player2.center_y = touch.y 


class ScreenThree(Screen): 
    pass 

class ScreenTwo(Screen): 
    pass 

class ScreenOne(Screen): 
    pass 

class Manager(ScreenManager): 

    screen_one = ObjectProperty(None) 
    screen_two = ObjectProperty(None) 
    screen_three = ObjectProperty(None) 

class ScreensApp(App): 

    def build(self): 
     m = Manager(transition=WipeTransition()) 
     return m 

if __name__ == '__main__': 
    ScreensApp().run() 

screen.kv：

<PongBall>: 
    size: 50, 50 
    canvas: 
     Ellipse: 
      pos: self.pos 
      size: self.size 

<PongPaddle>: 
    size: 25, 200 
    canvas: 
     Rectangle: 
      pos:self.pos 
      size:self.size 

<PongGame>: 
    ball: pong_ball 
    player1: player_left 
    player2: player_right 

    canvas: 
     Rectangle: 
      pos: self.center_x-5, 0 
      size: 10, self.height 

    Label: 
     font_size: 70 
     center_x: root.width/4 
     top: root.top - 50 
     text: str(root.player1.score) 

    Label: 
     font_size: 70 
     center_x: root.width * 3/4 
     top: root.top - 50 
     text: str(root.player2.score) 

    PongBall: 
     id: pong_ball 
     center: self.parent.center 

    PongPaddle: 
     id: player_left 
     x: root.x 
     center_y: root.center_y 

    PongPaddle: 
     id: player_right 
     x: root.width-self.width 
     center_y: root.center_y 

<ScreenOne>: 
    Button: 
     text: "Screen 1 >> Screen 2" 
     on_press: root.manager.current = 'screen2' 
<ScreenTwo>: 
     def build(self): 
      game = PongGame() 
      game.serve_ball() 
      Clock.schedule_interval(game.update, 1.0/60.0) 
      return game 

<ScreenThree>: 
    Button: 
     text: "Screen 3 >> Screen 1" 
     on_press: root.manager.current = 'screen1' 


<Manager>: 
    id: screen_manager 

    screen_one: screen_one 
    screen_two: screen_two 
    screen_three: screen_three 

    ScreenOne: 
     id: screen_one 
     name: 'screen1' 
     manager: screen_manager 

    ScreenTwo: 
     id: screen_two 
     name: 'screen2' 
     manager: screen_manager 

    ScreenThree: 
     id: screen_three 
     name: 'screen3' 
     manager: screen_manager 

Answer 1

嘛！你的程序中有很多错误，我不得不做出改进。 （我理解你是初学者）

首先，请仔细阅读完整的kivy language documentation，因为我可以清楚地看到你直接从编码开始而不掌握基本知识。 您可以制作几款优秀的游戏，但从长远来看，您将面临如果没有明确概念就无法解决的问题。 不幸的是，你将无法发现kivy的真实权力。 :)

您可能还想修改您的python概念。

一些改进不值得一提，但很重要，当你阅读代码时你会明白。

改进1：

如果您在建立（）返回一个小部件的应用程序可以建立，或者如果您设置self.root（但你不能再ñ再次提出申请） 你在这里做的：

<ScreenTwo>: 
    def build(self): 
     game = PongGame() 
     game.serve_ball() 
     Clock.schedule_interval(game.update, 1.0/60.0) 
     return game 

改进2：

当你点击按钮打乒乓球这是屏幕游戏。你的游戏始于球的服务。

on_release: root.current = 'game';game.serve_ball() 

（知识）

如果你仍然得到你可能要检查kivy文件的名称黑屏，为您既可以去kivy文档或this link

class PongPaddle(Widget): 
    score = NumericProperty(0) 

    def bounce_ball(self, ball): 
     if self.collide_widget(ball): 
      vx, vy = ball.velocity 
      offset = (ball.center_y - self.center_y)/(self.height/2) 
      bounced = Vector(-1 * vx, vy) 
      vel = bounced * 1.1 
      ball.velocity = vel.x, vel.y + offset 


class PongBall(Widget): 
    velocity_x = NumericProperty(0) 
    velocity_y = NumericProperty(0) 
    velocity = ReferenceListProperty(velocity_x, velocity_y) 

    def move(self): 
     self.pos = Vector(*self.velocity) + self.pos 


class PongGame(Widget): 
    ball = ObjectProperty(None) 
    player1 = ObjectProperty(None) 
    player2 = ObjectProperty(None) 

    def __init__(self, *args, **kwargs): 
     super(PongGame, self).__init__(*args, **kwargs) 
     Clock.schedule_interval(self.update, 1.0/60.0) 

    def serve_ball(self, vel=(4, 0)): 
     self.ball.center = self.center 
     self.ball.velocity = vel 

    def update(self, dt): 
     self.ball.move() 

     #bounce of paddles 
     self.player1.bounce_ball(self.ball) 
     self.player2.bounce_ball(self.ball) 

    #bounce ball off bottom or top 
     if (self.ball.y < self.y) or (self.ball.top > self.top): 
     self.ball.velocity_y *= -1 

    #went of to a side to score point? 
     if self.ball.x < self.x: 
      self.player2.score += 1 
      self.serve_ball(vel=(4, 0)) 
     if self.ball.x > self.width: 
      self.player1.score += 1 
      self.serve_ball(vel=(-4, 0)) 

    def on_touch_move(self, touch): 
     if touch.x < self.width/3: 
      self.player1.center_y = touch.y 
     if touch.x > self.width - self.width/3: 
      self.player2.center_y = touch.y 

class Manager(ScreenManager): 
    pass 

class ScreensApp(App): 
    def build(self): 
     self.load_kv('t6.kv') 
     return Manager(transition=WipeTransition()) 

if __name__ == '__main__': 
    ScreensApp().run() 

这是kv文件。

<PongBall>: 
    size: 50, 50 
    canvas: 
     Ellipse: 
      pos: self.pos 
      size: self.size 

<PongPaddle>: 
    size: 25, 200 
    canvas: 
     Rectangle: 
      pos:self.pos 
      size:self.size 

<PongGame>: 
    ball: pong_ball 
    player1: player_left 
    player2: player_right 

    canvas: 
     Rectangle: 
      pos: self.center_x-5, 0 
      size: 10, self.height 

    Label: 
     font_size: 70 
     center_x: root.width/4 
     top: root.top - 50 
     text: str(root.player1.score) 

    Label: 
     font_size: 70 
     center_x: root.width * 3/4 
     top: root.top - 50 
     text: str(root.player2.score) 

    PongBall: 
     id: pong_ball 
     center: self.parent.center 

    PongPaddle: 
     id: player_left 
     x: root.x 
     center_y: root.center_y 

    PongPaddle: 
     id: player_right 
     x: root.width-self.width 
     center_y: root.center_y 

<Manager>: 
    id: screen_manager 


    Screen: 
     name: 'home' 
     Button: 
      text: 'Play Ping Pong' 
      halign: 'center' 
      valign: 'middle' 
      font_size: 100 
      text_size: self.size 
      on_release: root.current = 'game';game.serve_ball() 

    Screen: 
     name: 'game' 
     PongGame: 
      id: game