Question

我正在使用教程中给出的PongGame代码练习Kivy。我想知道如何从新创建的类PongSample中调用类PongGame中的函数 - serve_ball2（）。在下面的代码中，我创建了一个PongSample类，在第一个球与桨碰撞时为第二个球提供服务。

更新：我可以从PongSample调用serve_ball2（），但是serve_ball2（）没有按预期运行，即它不起作用。

我已经分享了下面的完整代码。提前致谢

Pong.py：

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.properties import NumericProperty, ReferenceListProperty,\
    ObjectProperty
from kivy.vector import Vector
from kivy.clock import Clock, time
from threading import Thread

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
            PongSample().call_game()

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 PongSample(Widget):
    def call_game(self):
        print 'PongSample'
        ponggame=PongGame()
        ponggame.serve_ball2()

class PongGame(Widget):
    ball = ObjectProperty(None)
    ball2 = 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 serve_ball2(self, vel=(3, 0)):  
        print 'Serve_ball2'
        self.ball2.center = self.center
        self.ball2.velocity = vel

    def serve_down(self):
        print 'Inside Serve Down'
        self.ball.center = self.center
        self.ball.velocity = Vector(4,0).rotate(-90)

    def update(self, dt):
        self.ball.move()
        self.ball2.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
        if (self.ball2.y < self.y) or (self.ball2.top > self.top):
            self.ball2.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.ball2.x < self.x:
            self.player2.score += 1
            self.serve_ball2(vel=(3, 0))
        if self.ball2.x > self.width:
            self.player1.score += 1
            self.serve_ball2(vel=(-3, 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 PongApp(App):
    def build(self):
        game = PongGame()
        game.serve_ball()
        Clock.schedule_interval(game.update, 1.0 / 60.0)
        return game

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

pong.kv：

    #:kivy 1.8.0

<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
    ball2: pong_ball2
    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

    PongBall:
        id: pong_ball2
        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

Answer 1

要使用您的课程，请添加game.serve_ball2() to PongApp

class PongApp(App):
    def build(self):
        game = PongGame()
        game.serve_ball()
        game.serve_ball2()
        Clock.schedule_interval(game.update, 1.0 / 60.0)
        return game

添加self.ball2以反弹拨片：

#bounce of paddles
self.player1.bounce_ball(self.ball)
self.player2.bounce_ball(self.ball)
self.player1.bounce_ball(self.ball2)
self.player2.bounce_ball(self.ball2)

Answer 2

我强调这似乎是不必要的，PongSample本身似乎根本不存在。但是，为了做你所问的，我相信以下内容应该有效。然而，我真的不喜欢这个，就是在kv文件中创建一个PongSample实例，除了为ball2提供服务之外没有任何其他目的。然而...

为什么不在serve_ball2类中定义PongSample函数，并将ball2传递给它？

示例：

class PongSample(Widget):

    def serve_ball2(self, ball2, vel=(3,0)):
        print 'Serve ball 2'
        ball2.center = self.center
        ball2.velocity = vel

在PongGame课程中：

class PongGame(Widget):
    ball = ObjectProperty(None)
    ball2 = ObjectProperty(None)
    player1 = ObjectProperty(None)
    player2 = ObjectProperty(None)
    # add this
    sample = ObjectProperty(None)

然后在kv文件中：

# add at the top

<PongSample>:
    size: self.size
    pos: self.pos

# add the below in appropriate places within the PongGame definition

PongGame:
    sample: pong_sample

    PongSample:
        id: pong_sample # now it's linked to 'sample' in PongGame

现在在PongGame中，您可以通过任何方法调用self.sample.serve_ball2(ball2)。

如何从kivy Pong球类游戏中的另一个类中调用一个函数

2 个答案: