python - 为 "space invader"制作子弹

Question

我正在尝试在我的太空入侵者版本中为我的飞船制作射弹。我认为现在唯一不起作用的是显示所有射弹，因为我不知道如何，这就是为什么我尝试使用 blit，但不起作用。另外我想延迟每个射弹之间的时间，但我不知道该怎么做。到目前为止，这是我做过的最先进的屏幕相关程序。

import pygame
pygame.init()

class Player():
    def __init__(self):
        self.originalImage = pygame.image.load("ship.png")
        self.image = self.originalImage
        self.xposition = 480
        self.yposition = 450
        self.speed = 1

class Projectile():
    def __init__(self):
        self.originalImage = pygame.image.load("shot.png")
        self.image = self.originalImage
        self.xposition = player.xposition
        self.yposition = player.yposition
        self.speed = 1


size = width, height = 960, 540
screen = pygame.display.set_mode(size)
background = 0, 0, 0
player = Player()
projectile = Projectile()
projectiles = []
keys = pygame.key.get_pressed()

while True:
    screen.fill(background)

    for projectile in projectiles:
        if projectile.yposition < height:
            projectile.yposition -= projectile.speed
        else:
            projectiles.pop(projectiles.index(projectile))

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

    if (keys[pygame.K_RIGHT] or keys[pygame.K_d]) == True:
        player.xposition += player.speed
    if (keys[pygame.K_LEFT] or keys[pygame.K_a]) == True:
        player.xposition -= player.speed
    if (keys[pygame.K_SPACE] or keys[pygame.K_w] or keys[pygame.K_UP]) == True:
        projectiles.append(projectile)

    for projectile in projectiles:
        screen.blit(projectile.image, (projectile.xposition, projectile.yposition))

    screen.blit(player.image, ((player.xposition, player.yposition)))
    pygame.display.flip()

我在评论后编辑了代码，但仍然没有任何动静...

Answer 1

我建议使用pygame.sprite.Sprite 。从 Sprite 派生 Projectile。 Sprite 应该具有属性 .image 和 .rect。添加一个移动 Projectile 和 kill() 的方法当它超出界限时。例如:

class Projectile(pygame.sprite.Sprite):

    def __init__(self):
        super().__init__() 
        self.originalImage = pygame.image.load("shot.png")
        self.image = self.originalImage
        self.rect = self.image.get_rect(center = (player.xposition, player.yposition))
        self.speed = 1

    def move(self):
        self.rect.y -= self.speed
        if self.rect.y < 0:
            self.kill()

创建 pygame.sprite.Group容纳射弹:

projectiles = pygame.sprite.Group()

Group中的 Sprite 可以通过 .draw() 来绘制.

projectiles.draw(screen)

每次玩家发射子弹时，都必须创建一个新的子弹实例并将其添加到子弹组中。我向我们推荐键盘事件:

for event in pygame.event.get():
    # [...]

    if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_SPACE or event.key == pygame.K_w or event.key == pygame.K_UP: 
            projectiles.add(Projectile())

按键的状态 (keys = pygame.key.get_pressed()) 必须在主应用程序循环中进行评估。应用程序的速度可以通过 pygame.time.Clock() 控制:

import pygame
pygame.init()

class Player(pygame.sprite.Sprite):
    def __init__(self):
        self.originalImage = pygame.image.load("ship.png")
        self.image = self.originalImage
        self.rect = self.image.get_rect(center = (480, 450))
        self.speed = 1

class Projectile(pygame.sprite.Sprite):

    def __init__(self):
        super().__init__() 
        self.originalImage = pygame.image.load("shot.png")
        elf.image = self.originalImage
        self.rect = self.image.get_rect(center = player.rect.center)
        self.speed = 1

    def move(self):
        self.rect.y -= self.speed
        if self.rect.y < 0:
            self.kill()


size = width, height = 960, 540
screen = pygame.display.set_mode(size)
clock = pygame.time.Clock()
background = 0, 0, 0
player = Player()
projectiles = pygame.sprite.Group()

run = True
while run:
    clock.tick(120)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        if event.type == pygame.KEYDOWN:
           if event.key == pygame.K_SPACE or event.key == pygame.K_w or event.key == pygame.K_UP: 
              projectiles.add(Projectile())

    keys = pygame.key.get_pressed()
    if (keys[pygame.K_RIGHT] or keys[pygame.K_d]) == True:
        player.rect.x += player.speed
    if (keys[pygame.K_LEFT] or keys[pygame.K_a]) == True:
        player.rect.x -= player.speed

    for projectile in projectiles:
        projectile.move()

    screen.fill(background)
    projectiles.draw(screen)
    screen.blit(player.image, player.rect.topleft)
    pygame.display.flip()