main.py

# Create App
# Create Game
# Build Game
# Run the App

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
from random import randint


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

    def bounce_ball(self,ball):
        if self.collide_widget(ball):
            ball.velocity_x *= -1


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

    # Latest Position = Current velocity + Current Position
    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):
        self.ball.velocity = Vector(6, 0).rotate(randint(0, 360))

    def update(self, dt):
        self.ball.move()
        if (self.ball.y < 0) or (self.ball.y > self.height - 50):
            self.ball.velocity_y *= -1
        if self.ball.x < 0:
            self.ball.velocity_x *= -1
            self.player2.score += 1
        if self.ball.x > self.width - 50:
            self.ball.velocity_x *= -1
            self.player1.score += 1
        self.player1.bounce_ball(self.ball)
        self.player2.bounce_ball(self.ball)

    def on_touch_move(self, touch):
        if touch.x < self.width/ 1/4:
            self.player1.center_y = touch.y
        if touch.x > self.width * 3/4:
            self.player2.center_y = touch.y


class PongApp(App):
    def build(self):
        game = PongGame()
        game.serve_ball()
        Clock.schedule_interval(game.update, 1.0 / 80.0)
        return game


PongApp().run()