为什么我的函数keyMoveSprite()不能看到全局变量x_coordinate，y_coordinate？

Question

谢谢你提前帮忙。我对Python语言很陌生，并使用这个项目来学习Python，现在它使用一个函数将瓷砖绘制到屏幕上，我正在努力获得一个sprite，以便能够使用按键移动。问题是我的函数keyMoveSprite()不能看到全局变量x_coordinate和y_coordinate。它们在我的函数中，但这导致我的sprite没有移动，因为x和y变量每次迭代都被设置为0，所以我认为它们需要在循环之外。有什么建议吗？这是我的密码。我认为这个问题可能是因为在游戏的主循环中被反复调用的函数，但是需要反复调用它来跟踪输入。

import pygame,sys
from pygame.locals import *

pygame.init()  

#Global Variables
screen_x = 800
screen_y = 480
screen =  pygame.display.set_mode((screen_x, screen_y))
x_coordinate = 0
y_coordinate = 0
moveX, moveY = 0, 0


#This function will take the screen coordinates and draw
#a tile to the entire screen. It will draw tiles no matter
#the screen size.

def keyMoveSprite():
    sprite = pygame.image.load("character.png").convert_alpha()

    for event in pygame.event.get():

        if event.type == KEYDOWN:
            if event.key == K_LEFT:
                moveX = -10
            elif event.key == K_RIGHT:
                moveX = +10
            elif event.key == K_UP:
                moveY = -10
            elif event.key == K_DOWN:
                moveY = +10

        if event.type == KEYUP:
            if event.key == K_LEFT:
                moveX = 0
            elif event.key == K_RIGHT:
                moveX = 0
            elif event.key == K_UP:
                moveY = 0
            elif event.key == K_DOWN:
                moveY = 0

    x_coordinate = x_coordinate + moveX
    y_coordinate = y_coordinate + moveY

    screen.blit(sprite,(x_coordinate, y_coordinate))
    pygame.display.update()
    print("Character drawn at:", x_coordinate, y_coordinate)


def mapDraw(screen_x, screen_y):



    floor = pygame.image.load("floor_tile.png")
    wall = pygame.image.load("wall_tile.png")
    treasure = pygame.image.load("treasure_chest.png")

# Intialize row for loop
    row = 0
    mapColumn = 0
    mapRow = 0

#Loop between the values 0 to the screen's y variable, in intervals of
#32, and store them in the variable row once per loop.

    mapArray = [
        [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1],
        [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1],
        [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]
        ]


    for row in range(0, screen_y, 32):
        column = 0 # Set column to 0 per iteration, this allows reset of the x coordinate
        print("Map Row Value:", mapRow)
        mapColumn = 0 # Resets mapColumn variable to 0
        for column in range(0, screen_x, 32):

            if mapArray[mapRow][mapColumn] == 0:

                screen.blit(floor, (column, row)) 
                #print(column,row)
                pygame.display.update()
                #print("Map Column Value:",mapColumn)
                print("MapCol",mapColumn,"MapRow",mapRow)

            elif mapArray[mapRow][mapColumn] == 1:
                screen.blit(wall, (column, row))
                pygame.display.update()







            mapColumn = mapColumn + 1

        mapRow = mapRow + 1


def main():

    mapFloor = mapDraw(800,480)
    while True:

        keyMoveSprite()

main()

Answer 1

尝试使用global keyword，以便解释器可以消除x_coordinate和y_coordinate的本地分配之间的歧义。

def keyMoveSprite():
    global x_coordinate, y_coordinate
    # The rest of your code...

解决这个问题的一个更好的方法是创建一个类来表示您的玩家、它的位置以及与它相关的其他状态，而不是将所有东西存储在全局中。