Keys do not move sprite properly in pygame, strange behavior [duplicate]

Question

: ：

How to get keyboard input in pygame? (10 answers)

How can I make a sprite move when key is held down (3 answers)

Closed 7 months ago .

So I've been exparimenting with pygame, I can draw my sprite, but when I press WASD I have to press them all many times, and all the sprite does is move down and side to side, with no real control

I update the self.rect in the sprite class, and when you press a key it clears the screen and should redraw the sprite with a different xy position.

Here's the code:

import pygame
pygame.init()

screen = pygame.display.set_mode((750, 750))

BLACK = (0, 0, 0)
WHITE = (255,255,255)
RED = (255,0,0)

class Sprite(pygame.sprite.Sprite):
    def __init__(self, pos):
        super(Sprite, self).__init__()
        self.image = demon
        self.rect = self.image.get_rect(center = pos)
    
    def update(self, moveX, moveY):
        self.rect.x += moveX
        self.rect.y += moveY
        
        

        
        
all_sprites_list = pygame.sprite.Group()

demon = pygame.image.load("C:/programming/doomman/cacodemon.png").convert_alpha()

x = 300
y = 300

my_sprite = Sprite((x, y))
all_sprites_list.add(my_sprite)
clock = pygame.time.Clock()
pygame.display.set_caption("Demon Dance")
carryOn = True
        
while carryOn == True:
    keys = pygame.key.get_pressed()
    
    for event in pygame.event.get():
            if event.type==pygame.QUIT:
                carryOn=False
            elif event.type == pygame.KEYDOWN:
                screen.fill(BLACK)
                if keys[pygame.K_w]:
                    my_sprite.update(50, 0)
                if keys[pygame.K_s]:
                    my_sprite.update(-50, 0)
                if keys[pygame.K_d]:
                    my_sprite.update(0, 50)
                if keys[pygame.K_a]:
                    my_sprite.update(0, 50)
    
    
    pygame.display.flip()
    clock.tick(60)
    all_sprites_list.draw(screen)

Answer 1

pygame.key.get_pressed() returns a list with the state of all keyboard buttons. This is not intended to get the key of a keyboard event. The key that was pressed can be obtained from the key attribute of the pygame.event.Event object:

while carryOn == True:
    # [...]
    
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            carryOn=False
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_w:
                my_sprite.update(50, 0)
            if event.key == pygame.K_s:
                my_sprite.update(-50, 0)
            if event.key == pygame.K_d:
                my_sprite.update(0, 50)
            if event.key == pygame.K_a:
                my_sprite.update(0, 50)

    # [...]

The keyboard events (see pygame.event module) occur only once when the state of a key changes. The KEYDOWN event occurs once every time a key is pressed. KEYUP occurs once every time a key is released. Use the keyboard events for a single action or a step-by-step movement.

pygame.key.get_pressed() returns a list with the state of all keyboard buttons. This is not intended to get the key of a keyboard event. The key that was pressed can be obtained from the key attribute of the pygame.event.Event object.

However, you must evaluate the keys in the application loop rather than the event loop:

while carryOn == True:
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            carryOn=False
            
    keys = pygame.key.get_pressed()
    if keys[pygame.K_w]:
        my_sprite.update(50, 0)
    if keys[pygame.K_s]:
        my_sprite.update(-50, 0)
    if keys[pygame.K_d]:
        my_sprite.update(0, 50)
    if keys[pygame.K_a]:
        my_sprite.update(0, 50)

    # [...]