Ball Object for a Pong Game on the SSaurel's Blog

Ball.py

# First, we design the Ball Object
class Ball:
    def __init__(self, canvas, width, velocity, boardwidth, boardheight):
        self.width = width
        self.boardwidth = boardwidth
        self.boardheight = boardheight
        # we center the ball on the board
        self.topx = boardwidth / 2 - width / 2
        self.topy = boardheight / 2 - width / 2
        self.velocity = velocity
        self.vx = velocity
        self.vy = velocity
        self.canvas = canvas
        self.id = self.canvas.create_rectangle(self.topx, self.topy, self.topx + self.width, self.topy + self.width, fill = 'white')
        
    # we define a method to draw the ball on the canvas
    def draw(self):
        self.canvas.coords(self.id, self.topx, self.topy, self.topx + self.width, self.topy + self.width)
        
    # we define a restart method for restarting the ball move
    def restart(self):
        self.topx = self.boardwidth / 2 - self.width / 2
        self.topy = self.boardheight / 2 - self.width / 2
        # we define a random direction for the ball when restarting
        self.vx = (-1, 1)[rand.random() > 0.5] * self.velocity
        self.vy = (-1, 1)[rand.random() > 0.5] * self.velocity
        
    # Move the ball
    # we need to pass the pong game instance and the paddles in the move method of the Ball. You can improve this by yourself later ;)
    def move(self, pong, paddleright, paddleleft):
        # if the ball touches the top or the bottom of the board, we invert direction y
        if self.topy <= 0 or (self.topy + self.width) >= self.boardheight:
            self.vy = self.vy * -1
            
        # if the ball touches one of both paddles, we invert direction x
        if paddleright.collideright(self) or paddleleft.collideleft(self):
            self.vx = self.vx * -1
        
        # if the ball touches the right or the left of the board, we update paddle points and we return True
        if (self.topx + self.width) >= self.boardwidth:
            pong.leftpoints = pong.leftpoints + 1
            return True
        
        if self.topx <= 0:
            pong.rightpoints = pong.rightpoints + 1
            return True
        
        # we update ball position
        self.topx = self.topx + self.vx
        self.topy = self.topy + self.vy
        
        return False