How to change the snake head direction in pygame?

Question

I want it so that when i press my left arrow key (for example) the snake head will move towards the left. I have been using the pygame.display.flip command for that but that would mean if i keep clicking my left key it continually flips left and right.

if event.key == K_LEFT:  
                block = pygame.transform.flip(block, True, False) 
                block_x -= 20

(rest of my code if it helps)

        import pygame
from pygame.locals import *

def draw_block():   
    surface.fill((44, 250, 150))
    surface.blit(block, (block_x, block_y))
    pygame.display.update

def change_direction():
    block = pygame.display.flip


pygame.init()

WND_RES = (800, 600)

surface = pygame.display.set_mode(WND_RES)
surface.fill((44, 250, 150))

block_x = 100
block_y = 100

block = pygame.image.load("resources/pogchamp.jpg").convert()

surface.blit(block,(block_x,block_y))

pygame.display.update()

running = True

while running:
    
    for event in pygame.event.get():
        if event.type == KEYDOWN:
            pass
            if event.key == K_ESCAPE:
                running = False 
            if event.key == K_UP:
                block_y -= 20
                draw_block()
            if event.key == K_DOWN:
                block_y += 20
                draw_block()
            if event.key == K_LEFT:  
                block = pygame.transform.flip(block, True, False) 
                block_x -= 20
                draw_block()
            if event.key == K_RIGHT:
                block_x += 20
                block = pygame.transform.flip(block, True, False)
                draw_block()
        elif event.type == QUIT:
            running = False

    pygame.display.update()

Related [How do I chain the movement of a snake's body?](https://stackoverflow.com/questions/62010434/how-do-i-chain-the-movement-of-a-snakes-body/62010435#62010435) — Rabbid76, Oct 22 '21 at 12:04

TeemSy · Answer 1 · 2021-10-22T10:15:24.830

Ok, from what I've seen every time you enter the event, you flip your image like that.

    if event.key == K_LEFT:  
                block = pygame.transform.flip(block, True, False) 
                block_x -= 20
                draw_block()

So I added conditions to know when the head must turn right or left

    if event.key == K_LEFT:
                if flip_left is False and flip_right is True: ## HERE ##
                    block = pygame.transform.flip(block, True, False)
                    flip_left, flip_right = True, False ## HERE ##
                block_x -= 20
                draw_block()
                
            if event.key == K_RIGHT:
                if flip_right is False and flip_left == True:## HERE ##
                    block = pygame.transform.flip(block, True, False)
                    flip_left, flip_right = False, True ## HERE ##

So here is the rest of your code, I marked the changes with "## HERE ##"

import pygame
from pygame.locals import *

def draw_block():   
    surface.fill((44, 250, 150))
    surface.blit(block, (block_x, block_y))
    pygame.display.update

def change_direction():
    block = pygame.display.flip


pygame.init()

WND_RES = (1080, 960)

surface = pygame.display.set_mode(WND_RES)
surface.fill((44, 250, 150))

block_x = 100
block_y = 100

block = pygame.image.load("pogchamp.jpg").convert()


surface.blit(block,(block_x,block_y))

pygame.display.update()

running = True



flip_left = False  ## HERE ##
flip_right = True ## HERE ##  He starts to look to the right

while running:
    
    for event in pygame.event.get():
        if event.type == KEYDOWN:
            pass
            if event.key == K_ESCAPE:
                running = False 
            if event.key == K_UP:
                block_y -= 20
                draw_block()
            if event.key == K_DOWN:
                block_y += 20
                draw_block()


            if event.key == K_LEFT:
                if flip_left is False and flip_right is True: ## HERE ##
                '''when you click to look on the left, it checks if it is not 
                already done and if it is not it exchanges the status'''
    
                    block = pygame.transform.flip(block, True, False)
                    flip_left, flip_right = True, False ## HERE ##
                block_x -= 20
                draw_block()
                
            if event.key == K_RIGHT:
                if flip_right is False and flip_left == True: ## HERE ##
                    block = pygame.transform.flip(block, True, False)
                    flip_left, flip_right = False, True ## HERE ##

                block_x += 20
                draw_block()
        elif event.type == QUIT:
            running = False

    pygame.display.update()

score 0 · Answer 2 · answered Oct 24 '21 at 07:34

pygame.display.update is a function. You need the Parentheses (see Calls) to call a function:

~~pygame.display.update~~

pygame.display.update()

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()

Add a variable that indicates the direction of the obejct:

direction = (1, 0)

Change the variable in the event loop depending on the key pressed:

for event in pygame.event.get():
    if event.type == KEYDOWN:
        if event.key == K_ESCAPE:
            running = False 
        if event.key == K_UP:
            direction = (0, -1)
        if event.key == K_DOWN:
            direction = (0, 1)
        if event.key == K_LEFT:  
            direction = (-1, 0)
            block = block_left 
        if event.key == K_RIGHT:
            direction = (1, 0)
            block = block_right

Move the block in the application loop, depending on the direction:

step = 20
block_x += step * direction[0]
block_y += step * direction[1]

Minimal example:

import pygame
from pygame.locals import *

pygame.init()
WND_RES = (800, 600)
surface = pygame.display.set_mode(WND_RES)

block_x, block_y = 100, 100
# block = pygame.image.load("resources/pogchamp.jpg").convert()
block = pygame.image.load(r"C:\source\PyGameExamplesAndAnswers\resource\icon\Bird64.png")
block_right = block
block_left = pygame.transform.flip(block, True, False) 
direction = (1, 0)

def draw_block():   
    surface.blit(block, (block_x, block_y))

clock = pygame.time.Clock()
running = True
while running:
    clock.tick(10)
    for event in pygame.event.get():
        if event.type == KEYDOWN:
            pass
            if event.key == K_ESCAPE:
                running = False 
            if event.key == K_UP:
                direction = (0, -1)
            if event.key == K_DOWN:
                direction = (0, 1)
            if event.key == K_LEFT:  
                block = block_left 
                direction = (-1, 0)
            if event.key == K_RIGHT:
                direction = (1, 0)
                block = block_right
        elif event.type == QUIT:
            running = False

    step = 20
    block_x += step * direction[0]
    block_y += step * direction[1]

    surface.fill((44, 250, 150))
    draw_block()
    pygame.display.update()

How to change the snake head direction in pygame?

2 Answers2