Increase the ball speed as Pong game progress

Question

I am writing a Pong clone and I want to make the game get harder as the game progress. For every point (or few points), increase the speed of the ball.

My code is as follows:

import pygame
import sys
import math

class Ball(object):
    def __init__(self, x, y, width, height, vx, vy, colour):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.vx = vx
        self.vy = vy
        self.colour = colour



    def render(self, screen):
        pygame.draw.ellipse(screen, self.colour, self.rect)

    def update(self):
        self.x += self.vx
        self.y += self.vy

    @property
    def rect(self):
        return pygame.Rect(self.x, self.y, self.width, self.height)


class Paddle(object):
    def __init__(self, x, y, width, height, speed, colour):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.vx = 0
        self.speed = speed
        self.colour = colour

    def render(self, screen):
        pygame.draw.rect(screen, self.colour, self.rect)

    def update(self):
        self.x += self.vx

    def key_handler(self, event):
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                self.vx = -self.speed
            elif event.key == pygame.K_RIGHT:
                self.vx = self.speed
        elif event.key in (pygame.K_LEFT, pygame.K_RIGHT):
                self.vx = 0

    @property
    def rect(self):
        return pygame.Rect(self.x, self.y, self.width, self.height)   
        

class Pong(object):
    COLOURS = {"BLACK": (  0,   0,   0),
               "WHITE": (255, 255, 255),
               "RED"  : (255,   0,   0)}
    def __init__(self):
        pygame.init()
        (WIDTH, HEIGHT) = (640, 480)
        self.screen = pygame.display.set_mode((WIDTH, HEIGHT))
        pygame.display.set_caption("smach ball hit")
        self.ball = Ball(5, 5, 50, 50, 5, 5, Pong.COLOURS["BLACK"])
        self.paddle = Paddle(WIDTH / 2, HEIGHT - 50, 100,
                             10, 3, Pong.COLOURS["BLACK"])
        self.score = 0
 
    def play(self):
        clock = pygame.time.Clock()
        while True:
            clock.tick(50)
            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    pygame.quit()
                    sys.exit()
                if event.type in (pygame.KEYDOWN, pygame.KEYUP):
                    self.paddle.key_handler(event)

            self.collision_handler()
            self.draw()

    def collision_handler(self):
        if self.ball.rect.colliderect(self.paddle.rect):
            self.ball.vy = -self.ball.vy
            self.score += 1
           
  
        if self.ball.x + self.ball.width >= self.screen.get_width():
            self.ball.vx = -(math.fabs(self.ball.vx))
        elif self.ball.x <= 0:
            self.ball.vx = math.fabs(self.ball.vx)

        if self.ball.y + self.ball.height >= self.screen.get_height():
            pygame.quit()
            sys.exit()
        elif self.ball.y <= 0:
            self.ball.vy = math.fabs(self.ball.vy)

        if self.paddle.x + self.paddle.width >= self.screen.get_width():
            self.paddle.x = self.screen.get_width() - self.paddle.width
        elif self.paddle.x <= 0:
            self.paddle.x = 0

    def draw(self):
        self.screen.fill(Pong.COLOURS["WHITE"])

        font = pygame.font.Font(None, 48)
        score_text = font.render("Score: " + str(self.score), True,
                                 Pong.COLOURS["RED"])
        self.screen.blit(score_text, (0, 0))

        self.ball.update()
        self.ball.render(self.screen)
        self.paddle.update()
        self.paddle.render(self.screen)

        pygame.display.update()

if __name__ == "__main__":
    Pong().play()

I am pretty new to programming and I don't know much of how it works. For the code that is already there, I had a friend who is more experienced to help me.

Answer 1

I suggest you to add one method that updates the ball speed depending on the score, and you can call it just after the collision detection (because there is where you increase the score). You can include a call to that method like this, inside your play method:

        # (...) all your current code
        self.collision_handler()
        self.speed_up()
        self.draw()

And, in the method implementation, you can divide your score, for example by 10, and add it as extra speed. Tweak this value to more or less, so it will fit your game better.

def speed_up(self):
    delta = self.score // 10
    if self.ball.vx > 0:
        self.ball.vx += delta
    else:
        self.ball.vx -= delta
    if self.ball.vy > 0:
        self.ball.vy += delta
    else:
        self.ball.vy -= delta