如何在pygame中更新精灵位置？

Question

我一直在尝试让这个功能正常运作，已经看了很多其他的问题，但还是搞不定。
我想让精灵在按下箭头键时移动，但什么都没有发生。
精灵确实被画出来了，但就只有这一点。
这是我的代码。

import pygame, sys
from pygame.locals import *
from data import *


def main():
    def draw_map(Map):
        for row in range(MAPHEIGHT):
            #loop through each column in the row
            for column in range(MAPWIDTH):
                #draw the resource at that position in the tilemap, using the correct colour
                pygame.draw.rect(screen, colours[Map[row][column]], (column*TILESIZE,row*TILESIZE,TILESIZE,TILESIZE))
    def stop():
        pygame.quit()
        sys.exit()
    tilemap = [
               [white, white, white, white, white, white, white, white, white, white],
               [white, white, white, white, white, white, white, white, white, white],
               [white, white, white, white, white, white, white, white, white, white],
               [white, white, white, white, white, white, white, white, white, white],
               [white, white, white, white, white, white, white, white, white, white],
               [white, white, white, white, white, white, white, white, white, white],
               [white, white, white, white, white, white, white, white, white, white],
               [white, white, white, white, white, blue, blue, white, white, white],
               [white, white, white, white, white, white, white, white, white, white],
               [green, green, green, green, green, green, green, green, green, green]
              ] 

    entities = pygame.sprite.Group()

    class Entity(pygame.sprite.Sprite):
        def __init__(self):
            pygame.sprite.Sprite.__init__(self)

    class Player(Entity):
        def __init__(self):
            Entity.__init__(self)
            self.playerx = 50
            self.playery = 50
            self.image = pygame.image.load("p3_front.png")
            self.rect = Rect(self.playerx, self.playery, 66, 92)

    player = Player()
    pygame.init()

    # Set the width and height of the screen 
    screen = pygame.display.set_mode(size)

    pygame.display.set_caption("Game")

    # Used to manage how fast the screen updates
    clock = pygame.time.Clock()

    entities.add(player)

    # -------- Main Program Loop -----------
    while True:
        # ALL EVENT PROCESSING SHOULD GO BELOW THIS COMMENT
        for event in pygame.event.get():  # User did something
            if event.type == pygame.QUIT:  # If user clicked close
                stop()
        pressed = pygame.key.get_pressed() 
        if pressed[pygame.K_UP]: player.playery -= 3  
        if pressed[pygame.K_DOWN]: player.playery += 3
        if pressed[pygame.K_LEFT]: player.playerx -= 3
        if pressed[pygame.K_RIGHT]: player.playerx += 3

        # ALL EVENT PROCESSING SHOULD GO ABOVE THIS COMMENT


        # ALL GAME LOGIC SHOULD GO BELOW THIS COMMENT

        # ALL GAME LOGIC SHOULD GO ABOVE THIS COMMENT



        # ALL CODE TO DRAW SHOULD GO BELOW THIS COMMENT

        # First, clear the screen to white. Don't put other drawing commands
        # above this, or they will be erased with this command.
        screen.fill(white)
        draw_map(tilemap)
        entities.update()
        entities.draw(screen)

        # ALL CODE TO DRAW SHOULD GO ABOVE THIS COMMENT

        # Go ahead and update the screen with what we've drawn.
        pygame.display.flip()

        # Limit to 20 frames per second
        clock.tick(20)

    stop()

if __name__ == "__main__":
    main()

Answer 1

entities.update() 这个方法其实就是在调用它里面每个类的 update 方法。所以，你需要在你的 Player 类里创建一个方法，用来更新你想要的角色图像。对于 Player 类，这个方法可能会像这样：

class Player(Entity):
    def __init__(self):
        Entity.__init__(self)
        self.playerx = 50
        self.playery = 50
        self.image = pygame.image.load("p3_front.png")
        self.rect = Rect(self.playerx, self.playery, 66, 92)

    def update(self):
        self.rect = Rect(self.playerx, self.playery, 66, 92)

我建议你看看 这个链接。里面对 pygame 中 sprites 的工作原理有很好的解释。