Why is the sprite not moving?

Question

I am currently programming a pygame game where you move a spaceship around the screen. Currently, I have got to the part where I made the spaceship and tried to make it move. However, when I try to move the spaceship around, the spaceship doesn't move!

Here is my current code:

import pygame

pygame.init()
screen = pygame.display.set_mode((800, 500))
screen.fill((255, 255, 255))


class Spaceship(pygame.sprite.Sprite):
    def __init__(self, s, x, y):
        pygame.sprite.Sprite.__init__(self)

        self.screen = s
        self.x, self.y = x, y
        self.image = pygame.image.load("C:/eqodqfe/spaceship.png")
        self.image = pygame.transform.scale(self.image, (175, 175))
        self.rect = self.image.get_rect()
        self.rect.center = (self.x, self.y)

    def update(self):
        self.rect.center = (self.x, self.y)


spaceship = Spaceship(screen, 400, 400)
screen.blit(spaceship.image, spaceship.rect)

running = True
while running:
    for event in pygame.event.get():
       if event.type == pygame.QUIT:
            running = False

    key = pygame.key.get_pressed()
    if key[pygame.K_a]:
        spaceship.x -= 5
    elif key[pygame.K_d]:
        spaceship.x += 5
    elif key[pygame.K_w]:
        spaceship.y += 5
    elif key[pygame.K_s]:
        spaceship.y -= 5

    spaceship.update()
    pygame.display.update()

What is wrong with my current code?

Rabbid76 · Accepted Answer · 2021-03-19T19:49:23.110

2

You have to draw the Sprties in the application loop:

clock = pygame.time.Clock()
running = True
while running:
    
    # handle events
    for event in pygame.event.get():
       if event.type == pygame.QUIT:
            running = False

    key = pygame.key.get_pressed()
    if key[pygame.K_a]:
        spaceship.x -= 5
    elif key[pygame.K_d]:
        spaceship.x += 5
    elif key[pygame.K_w]:
        spaceship.y -= 5
    elif key[pygame.K_s]:
        spaceship.y += 5

    # update the position of the object
    spaceship.update()

    # clear the display 
    screen.fill((255, 255, 255))

    #  draw the object
    screen.blit(spaceship.image, spaceship.rect)

    # update the display
    pygame.display.update()

    # limit frames per second 
    clock.tick(60)

The typical PyGame application loop has to:

handle the events by 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 either pygame.display.update() or pygame.display.flip()
limit frames per second to limit CPU usage

Furthermore I suggest to use a pygame.sprite.Group:

pygame.sprite.Group.draw() and pygame.sprite.Group.update() are methods which are provided by pygame.sprite.Group.

The former delegates the to the update mehtod of the contained pygame.sprite.Sprites - you have to implement the method. See pygame.sprite.Group.update():

Calls the update() method on all Sprites in the Group [...]

The later uses the image and rect attributes of the contained pygame.sprite.Sprites to draw the objects - you have to ensure that the pygame.sprite.Sprites have the required attributes. See pygame.sprite.Group.draw():

Draws the contained Sprites to the Surface argument. This uses the Sprite.image attribute for the source surface, and Sprite.rect. [...]

spaceship = Spaceship(screen, 400, 400)
all_sprites = pygame.sprite.Group()
all_sprites.add(spaceship)

clock = pygame.time.Clock()
running = True
while running:
    clock.tick(60)
    for event in pygame.event.get():
       if event.type == pygame.QUIT:
            running = False

    key = pygame.key.get_pressed()
    if key[pygame.K_a]:
        spaceship.x -= 5
    elif key[pygame.K_d]:
        spaceship.x += 5
    elif key[pygame.K_w]:
        spaceship.y += 5
    elif key[pygame.K_s]:
        spaceship.y -= 5

    all_sprites.update()

    screen.fill((255, 255, 255))
    all_sprites.draw(screen)
    pygame.display.update()

edited Mar 19 '21 at 19:49

answered Mar 19 '21 at 17:43

Rabbid76

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1

Thanks! I understand now. That really helped me understand pygame better. – Alan Bagel Mar 19 '21 at 17:46
1

(don't forget to add a call to delay between frames in the eventloop, otherwise this takes 100% CPU) – jsbueno Mar 19 '21 at 17:46
1

@jsbueno No never use `delay`, but use [`pygame.time.Clock.tick()`](https://www.pygame.org/docs/ref/time.html) – Rabbid76 Mar 19 '21 at 17:49
Wait, in the group part, I only wanted one player. But if I was going to create an enemy class, the group part would definitely help. Thanks again! – Alan Bagel Mar 19 '21 at 17:53
1

@JiuJiu Yes of course, the group is intended for the use with more than 1 object However, there is [`pygame.sprite.GroupSingle`](https://www.pygame.org/docs/ref/sprite.html#pygame.sprite.GroupSingle). – Rabbid76 Mar 19 '21 at 17:57
Oh, so GroupSingle is a group with only one thing in it. Does it have mostly the same methods as Group? Should I use GroupSingle over no group at all? – Alan Bagel Mar 19 '21 at 18:09
1

@JiuJiu GroupSingle is rarely used. However it may be useful for functions like [`pygame.sprite.groupcollide`](https://www.pygame.org/docs/ref/sprite.html#pygame.sprite.groupcollide). It's up to you and depends on your need. I just wanted to point out that there is. – Rabbid76 Mar 19 '21 at 18:12
1

OK, thanks! (This is also my first post.) – Alan Bagel Mar 19 '21 at 18:19
1

@JiuJiu Thank you. You're welcome. – Rabbid76 Mar 19 '21 at 18:19
1

yes - `pygame.time.clock.tick` - sorry, I was going to write "a delay" in the previous comment, but intending you to talk about this. – jsbueno Mar 19 '21 at 19:44
2

@jsbueno At least I added the code to the answer. However, I cannot give a full tutorial in one answer. The answer has been far too long now. – Rabbid76 Mar 19 '21 at 19:47
Oh, that's okay. – Alan Bagel Mar 20 '21 at 17:45

Why is the sprite not moving?

1 Answers1