Paddles in pong aren't moving

Question

I want to move the left paddle using W and S, but whenever I click the keys the paddle doesn't move. I've only been learning python for a few months and pygame a few weeks, so if its a really obvious mistake then that's why.

Here's the main game loop:

while not x:
  for event in pygame.event.get():
    if event.type == pygame.QUIT: 
      x = True #quits the game when you press X
    if event.type == pygame.KEYUP: #makes start screen go away
      if event.key == pygame.K_RETURN:
        gamescreen() 
  
      ball = Ball(window, white, 350, 220, 7)
      p1Paddle = Paddle(window, blue, 50, 180, 10, 60)
      p2Paddle = Paddle(window, red, 630, 180, 11, 60)
  #moves the paddles
    if event.type == pygame.KEYDOWN:
      if event.key == pygame.K_w: #supposed to make the paddle go up
        p1Paddle.state = 'up'
        print('up')
        
    if event.type == pygame.KEYDOWN:
      if event.key == pygame.K_s: #supposed to make the paddle go down
        p1Paddle.state = 'down'
        p1Paddle.move()
        print('down')

    
    pygame.display.update()
    clock.tick(45)

and here's the paddle function/class.

class Paddle:
  def __init__(self, screen, colour, posX, posY, width, height):
    self.screen = screen
    self.colour = colour
    self.posX = posX
    self.posY = posY
    self.width = width
    self.height = height
    self.state = 'stopped'
    self.show()

  def show(self):
    pygame.draw.rect(self.screen, self.colour, (self.posX, self.posY, self.width, self.height))

  def move(self):
    if self.state == 'up':
      self.posY -= 10

    elif self.state == 'down':
      self.posY += 10

(I haven't gotten the chance to add the controls for the second paddle; I'll get there once I figure this one out.) It prints 'up' and 'down', so I know it works to some extent.

Rabbid76 · Accepted Answer · 2022-06-02T19:28:04.750

You need to create the objects before the application loop instead of in the application loop. But you have to draw the objects in each frame at their new position in the application loop:

p1Paddle = Paddle(window, blue, 50, 180, 10, 60)
p2Paddle = Paddle(window, red, 630, 180, 11, 60)
ball = Ball(window, white, 350, 220, 7)
 
while not x:
    # handle events
    for event in pygame.event.get():
        if event.type == pygame.QUIT: 
            x = True
        # [...] more events


    # clear screen
    window.fill(0)

    # draw objects
    p1Paddle.show()
    p2Paddle.show()
    ball.show()

    # update display
    pygame.display.update()
    clock.tick(45)

The typical PyGame application loop has to:

limit the frames per second to limit CPU usage with pygame.time.Clock.tick
handle the events by calling either pygame.event.pump() or pygame.event.get().
update the game states and positions of objects dependent on the input events and time (respectively frames)
clear the entire display or draw the background
draw the entire scene (blit all the objects)
update the display by calling either pygame.display.update() or pygame.display.flip()

@n.alha *"it just gets longer from the bottom"*. No it does not. You have to clear the display in every frame: `window.fill(0)` — Rabbid76, Jun 03 '22 at 14:41
I forgot to add that in; I edited the comment to say the actual problem instead. — n.alha, Jun 03 '22 at 14:42
@n.alha Which start screen? This is a completely different question. Read about [Pygame level/menu states](https://stackoverflow.com/questions/14700889/pygame-level-menu-states), [What is the better way to make multiple loops in pygame?](https://stackoverflow.com/questions/57908287/python-what-is-the-better-way-to-make-multiple-loops-in-pygame) and many more... — Rabbid76, Jun 03 '22 at 14:59

Paddles in pong aren't moving

1 Answers1