当移动特定数量的像素时，更改字符的图像

Question

我正在用pygame做游戏。每当角色移动一定数量的像素时，我想改变它的图像，使它看起来像是在走路，但我真的不明白怎么做。代码如下：

import pygame
import time
BLACK = (  0,   0,   0)
WHITE = (255, 255, 255)
RED   = (255,   0,   0)
GREY = (129, 129, 129)
frame = 0

class SpriteSheet(object):
    def __init__(self, file_name):
        self.sprite_sheet = pygame.image.load(file_name).convert()
    def get_image(self, x, y, width, height, colour):
        image = pygame.Surface([width, height]).convert()
        image.set_colorkey(colour)
        image.blit(self.sprite_sheet, (0, 0), (x, y, width, height))
        return image
class Bomb(pygame.sprite.Sprite):
    change_x =0
    change_y = 0
    def __init__(self):
        super().__init__()
        sprite_sheet = SpriteSheet("Untitled.png")
        self.image = sprite_sheet.get_image(2, 2, 48, 48, WHITE)
        self.rect = self.image.get_rect()
    def move(self, y):
        self.rect.y += y
        if self.rect.y == 400:
            self.kill()

class Soldier(pygame.sprite.Sprite):

    def __init__(self):
        self.change_x = 0
        self.change_y = 0
        self.direction = "R"
        super().__init__()
        self.walking_frames_l = []
        self.walking_frames_r = []
        
        sprite_sheet = SpriteSheet("Picture2.png")
        self.image = sprite_sheet.get_image(0, 0, 150, 205, GREY)
        self.walking_frames_l.append(self.image)

        self.image = sprite_sheet.get_image(233, 0, 140, 210, GREY)
        self.walking_frames_l.append(self.image)
        self.image = sprite_sheet.get_image(425, 5, 123, 210, GREY)
        self.walking_frames_l.append(self.image)

        self.image = sprite_sheet.get_image(0, 0, 150, 205, GREY)
        self.image = pygame.transform.flip(self.image, True, False)
        self.walking_frames_r.append(self.image)
        self.image = sprite_sheet.get_image(233, 0, 140, 210, GREY)
        self.image = pygame.transform.flip(self.image, True, False)
        self.walking_frames_r.append(self.image)
        self.image = sprite_sheet.get_image(425, 5, 123, 210, GREY)
        self.image = pygame.transform.flip(self.image, True, False)
        self.walking_frames_r.append(self.image)

        self.image = self.walking_frames_r[0]
        
        self.rect = self.image.get_rect()
        self.rect.y = 297
        self.rect.x = 100


    def move(self):
        self.rect.x += self.change_x
    def walk(self):
        global frame
        if self.change_x > 0:
            frame +=1
            time.sleep(.1)
        if frame == 3:
            frame = 0
        self.image = self.walking_frames_r[frame]

    def go_left(self):
        self.change_x = -6
 
    def go_right(self):
        self.change_x = 6
    def stop(self):
        self.change_x = 0
        self.image = self.walking_frames_r[2]
pygame.init()
screen_width = 1000
screen_height = 500
screen = pygame.display.set_mode([screen_width, screen_height])
pygame.display.set_caption("Game")
clock = pygame.time.Clock()
done = False
bomb  = Bomb()
soldier = Soldier()
all_sprites = pygame.sprite.Group()
all_sprites.add(bomb)
all_sprites.add(soldier)
while not done:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True
        if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_LEFT:
                    soldier.go_left()
                if event.key == pygame.K_RIGHT:
                    soldier.go_right()
        if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT and soldier.change_x < 0:
                soldier.stop()
            if event.key == pygame.K_RIGHT and soldier.change_x > 0:
                soldier.stop()
    
    screen.fill(RED)
    all_sprites.draw(screen)
    bomb.move(2)
    soldier.move()
    soldier.walk()
    clock.tick(60)
    pygame.display.flip()
pygame.quit()

我还尝试在特定时间后更改图像（此部分）：

    def walk(self):
        global frame
        if self.change_x > 0:
            frame +=1
            time.sleep(.1)
        if frame == 3:
            frame = 0
        self.image = self.walking_frames_r[frame]

当我添加time.sleep（.1）并尝试移动角色时，它会以某种方式影响炸弹。它移动2个像素，等待.1秒，然后再次移动2个像素

是否有任何方法可以执行上述任一操作（在特定时间后或在经过特定像素数后更改图像）

请帮忙。谢谢

Answer 1

frame必须是Soldier类的属性。此外，还需要一个attribute来显示播放器移动的像素数：

class Soldier(pygame.sprite.Sprite):
    def __init__(self):
        # [...]

        self.frame = 0
        self.moved = 0

将绝对移动添加到self.moved。当移动超过一定数量的像素（pixel_for_one_step ）时，增量frame：

class Soldier(pygame.sprite.Sprite):
    # [...]

    def walk(self):
        self.moved += abs(self.change_x)

        pixels_for_one_step = 60
        if self.moved > pixels_for_one_step:
            self.moved -= pixels_for_one_step
            self.frame += 1
            if self.frame >= len(self.walking_frames_r):
                self.frame = 0

        self.image = self.walking_frames_r[self.frame]

---

完整示例：

import pygame

BLACK = (  0,   0,   0)
WHITE = (255, 255, 255)
RED   = (255,   0,   0)
GREY = (129, 129, 129)

class SpriteSheet(object):
    def __init__(self, file_name):
        self.sprite_sheet = pygame.image.load(file_name).convert()
    def get_image(self, x, y, width, height, colour):
        image = pygame.Surface([width, height]).convert()
        image.set_colorkey(colour)
        image.blit(self.sprite_sheet, (0, 0), (x, y, width, height))
        return image
class Bomb(pygame.sprite.Sprite):
    change_x =0
    change_y = 0
    def __init__(self):
        super().__init__()
        sprite_sheet = SpriteSheet("Untitled.png")
        self.image = sprite_sheet.get_image(2, 2, 48, 48, WHITE)
        self.rect = self.image.get_rect()
    def move(self, y):
        self.rect.y += y
        if self.rect.y == 400:
            self.kill()

class Soldier(pygame.sprite.Sprite):

    def __init__(self):
        self.change_x = 0
        self.change_y = 0
        self.direction = "R"
        super().__init__()
        self.walking_frames_l = []
        self.walking_frames_r = []
        
        sprite_sheet = SpriteSheet("Picture2.png")
        self.image = sprite_sheet.get_image(0, 0, 150, 205, GREY)
        self.walking_frames_l.append(self.image)

        self.image = sprite_sheet.get_image(233, 0, 140, 210, GREY)
        self.walking_frames_l.append(self.image)
        self.image = sprite_sheet.get_image(425, 5, 123, 210, GREY)
        self.walking_frames_l.append(self.image)

        self.image = sprite_sheet.get_image(0, 0, 150, 205, GREY)
        self.image = pygame.transform.flip(self.image, True, False)
        self.walking_frames_r.append(self.image)
        self.image = sprite_sheet.get_image(233, 0, 140, 210, GREY)
        self.image = pygame.transform.flip(self.image, True, False)
        self.walking_frames_r.append(self.image)
        self.image = sprite_sheet.get_image(425, 5, 123, 210, GREY)
        self.image = pygame.transform.flip(self.image, True, False)
        self.walking_frames_r.append(self.image)

        self.image = self.walking_frames_r[0]
        
        self.rect = self.image.get_rect()
        self.rect.y = 297
        self.rect.x = 100
        self.frame = 0
        self.moved = 0


    def move(self):
        self.rect.x += self.change_x
    def walk(self):
        self.moved += abs(self.change_x)

        pixels_for_one_step = 60
        if self.moved > pixels_for_one_step:
            self.moved -= pixels_for_one_step
            self.frame += 1
            if self.frame >= len(self.walking_frames_r):
                self.frame = 0

        self.image = self.walking_frames_r[self.frame]

    def go_left(self):
        self.change_x = -6
 
    def go_right(self):
        self.change_x = 6
    def stop(self):
        self.change_x = 0
        self.image = self.walking_frames_r[2]
pygame.init()
screen_width = 1000
screen_height = 500
screen = pygame.display.set_mode([screen_width, screen_height])
pygame.display.set_caption("Game")
clock = pygame.time.Clock()
done = False
bomb  = Bomb()
soldier = Soldier()
all_sprites = pygame.sprite.Group()
all_sprites.add(bomb)
all_sprites.add(soldier)
while not done:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True
        if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_LEFT:
                    soldier.go_left()
                if event.key == pygame.K_RIGHT:
                    soldier.go_right()
        if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT and soldier.change_x < 0:
                soldier.stop()
            if event.key == pygame.K_RIGHT and soldier.change_x > 0:
                soldier.stop()
    
    screen.fill(RED)
    all_sprites.draw(screen)
    bomb.move(2)
    soldier.move()
    soldier.walk()
    clock.tick(60)
    pygame.display.flip()
pygame.quit()