Re: [pygame] Odd behaviour of sprites in a list - newbie help please?

[Sean Felipe Wolfe <ether.joe@xxxxxxxxx>]

Not a direct answer to your question, but I would factor out portions of your code into separate functions. There's one school of thought in the programming world that says functions or methods shouldn't be more than 10 lines of code. People can agree or disagree, but regardless it helps to debug a problem like this when the code is organized into named functions.

 

S for example, a common convention is to have a gameloop() function which would contain your root while: statement. Then within the gameloop, you could have a handle_keys() function which handles keys, a process_input, and an update_snake() to handle the graphics. You've probably seen the basic 'game loop' flow yes? Input -> process -> output -> wait ? ? 

For me, when I'm crunching through a difficult problem it often helps to do a cleanup refactor and shake loose my thinking.

Good luck :)

On Mon, Jun 24, 2019 at 8:19 AM Adam Coombes <mac.badmoose@xxxxxxxxx> wrote:

I've created a list of sprites to try and make a basic 'snake' game. The idea is to shuffle each sprite to the position of the next, starting at the end of the tail, and then move the head. As I append new tail pieces, they should 'snake' along. However, when I move the head sprite ( Snake[0] in my list 'Snake'), they all seem to move to the same position. Even when I omit the line that moves them along by commenting out 'Snake[tail] = Snake[tail-1]' in my for loop, it still moves every sprite in the list Snake[] to the same place as Snake[0], which is inexplicable to me as I'm not even moving them then. Can anyone point out my mistake please? This is just a learner project, but it's driving me nuts.

import pygame, sys

from pygame.locals import*

import random

#colours========================================================

BLACK = (0,0,0)

WHITE = (255,255,255)

RED = (255,0,0)

GREEN = (0,255,0)

BLUE = (0,0,255)

PURPLE = (128,0,128)

GREY = (128,128,128)

YELLOW = (255,255,0)

pygame.init()

Height = 1920

Width = 1080

score = 0

basicfont = pygame.font.SysFont(None, 50)

Score = basicfont.render("Score: " + str(score), True, WHITE, GREEN)

ScoreRect = Score.get_rect()

ScoreRect.left =560

ScoreRect.bottom = 130

moveLeft = False

moveRight = False

moveUp = False

moveDown = False

PlayerSpeed = 40

def GameBoard():

    pygame.display.set_caption("Snake_Game")

    Window.fill(GREEN)

    pygame.draw.line(Window, BLACK,(560,140),(1360,140),4)

    pygame.draw.line(Window, BLACK,(560,140),(560,940),4)

    pygame.draw.line(Window, BLACK,(1360,140),(1360,940),4)

    pygame.draw.line(Window, BLACK,(560,940),(1360,940),4)

#GAME===========================================================

mainClock = pygame.time.Clock()

Window = pygame.display.set_mode((Height,Width), 0, 32)

#PLayer=========================================================                    

Snake =[]

Snake.append (pygame.Rect(940,500,40,40))

playerImage = pygame.image.load("Snake.GIF")

Window.blit(playerImage,Snake[0])

#Apple==========================================================

def PlotApple():

    global AppleX

    global AppleY

    global Apple

    AppleX = random.randint(560,1320)

    AppleY = random.randint(140,900)

    Apple = pygame.Rect(AppleX,AppleY,40,40)

PlotApple()

AppleImage = pygame.image.load("Apple.GIF") 

Window.blit(AppleImage,Apple)

pygame.display.update()

#================================================================

while True:

    for event in pygame.event.get():

        if event.type == KEYDOWN:

            if event.key == K_ESCAPE:

                pygame.quit()

        #===================================================

        if event.type == KEYDOWN:

            #===============================================

            if event.key == K_LEFT:

                moveRight = False

                moveLeft = True

                moveDown = False

                moveUp = False

            #===============================================

            if event.key == K_RIGHT:

                moveLeft = False

                moveRight = True

                moveDown = False

                moveUp = False

            #===============================================

            if event.key == K_UP:

                moveDown = False

                moveUp = True

                moveLeft = False

                moveRight = False

            #===============================================

            if event.key ==K_DOWN:

                moveUp = False

                moveDown = True

                moveLeft = False

                moveRight = False

            #KEYUP===============================================

            if event.type == KEYUP:

            #===================================================

                if event.key == K_ESCAPE:

                    pygame.quit()

                    sys.exit()

    #MovePlayer===================================================

    mainClock.tick(10)

    GameBoard()

    for tail in range (len(Snake)-1,0,-1):

        print(Snake,tail)

        Snake[tail] = Snake[tail-1]

        Window.blit(playerImage,Snake[tail])

        print(Snake,tail)

    if moveDown:

        Snake[0].top += PlayerSpeed

    if moveUp:

        Snake[0].top -= PlayerSpeed

    if moveLeft:

        Snake[0].left -= PlayerSpeed

    if moveRight:

        Snake[0].right += PlayerSpeed

    if Snake[0].bottom >=940 or Snake[0].top<+140 or Snake[0].left<=560 or Snake[0].right>=1360:

        pygame.quit()

    Score = basicfont.render("Score:" + str(score), True, WHITE, GREEN)

    Window.blit(playerImage,Snake[0])

    Window.blit(AppleImage,Apple)

    Window.blit(Score,ScoreRect)

    if Snake[0].colliderect(Apple):

        score = score +50

        Snake.append (Snake[0])

        PlotApple()

    pygame.display.update()

--

A musician must make music, an artist must paint, a poet must write, if he is to be ultimately at peace with himself.
- Abraham Maslow