python飞机大战02-敌人精灵

1 敌人精灵

首先定义Mob(小怪物)类型：

class Mob(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((30,40))
        self.image.fill(RED)
        self.rect = self.image.get_rect()
        self.rect.x = random.randrange(WIDTH - self.rect.width)
        self.rect.y = random.randrange(-100, -40)
        self.speedy = random.randrange(1, 8)

   这里的关键是为小怪物初始化一个好的位置。选择一个高于顶部的值（y <0）和一个介于左右两边之间的x的随机值。
   在update函数中，更新精灵y轴的坐标，向下移动精灵；精灵离开底部时，通过将精灵移回顶部上方的随机位置来制造下一个精灵。

    def update(self):
        self.rect.y += self.speedy
        if self.rect.top > HEIGHT + 10:
            self.rect.x = random.randrange(WIDTH - self.rect.width)
            self.rect.y = random.randrange(-100, -40)
            self.speedy = random.randrange(1, 8)

2 一群敌机

   使用for语句，循环创建一些怪物，并将它们添加到精灵组中：

all_sprites = pygame.sprite.Group()
mobs = pygame.sprite.Group()
player = Player()
all_sprites.add(player)
for i in range(8):
    m = Mob()
    all_sprites.add(m)
    mobs.add(m)

现在应该有一群怪物涌入屏幕，如下所示：

这很棒，但让小怪直接向下移动有点无聊。让在x方向上添加一点运动：

class Mob(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((30, 40))
        self.image.fill(RED)
        self.rect = self.image.get_rect()
        self.rect.x = random.randrange(WIDTH - self.rect.width)
        self.rect.y = random.randrange(-100, -40)
        self.speedx = random.randrange(-3, 3)
        self.speedy = random.randrange(1, 8)

    def update(self):
        self.rect.x += self.speedx
        self.rect.y += self.speedy
        if self.rect.top > HEIGHT + 10 or self.rect.left < -50 or self.rect.right > WIDTH + 20:
            self.rect.x = random.randrange(WIDTH - self.rect.width)
            self.rect.y = random.randrange(-100, -40)
            self.speedy = random.randrange(1, 8)

注意：更改了怪物移出屏幕的判断语句。对角线移动的怪物可能会在它离开底部之前就离开侧面。

整合到一起：

# Shmup game - part 2
# shmup.py
# Enemy Sprites
import pygame
import random


WIDTH = 480  # width of our game window
HEIGHT = 600  # height of our game window
FPS = 60  # 60 frames per second


# Colors(R,G,B),define color
BLACK = (0,0,0)
WHITE = (255,255,255)
RED = (255,0,0)
GREEN = (0,255,0)
BLUE = (0,0,255)
YELLOW = (255,255,0)


# initialize pygame and create windw
pygame.init()  # 启动pygame并初始化
pygame.mixer.init()  # 声音初始化
screen = pygame.display.set_mode((WIDTH, HEIGHT))  # 游戏屏幕，按照在配置常量中设置的大小创建
pygame.display.set_caption("Shmup!")
icon = pygame.image.load("img/p1_jump.png")
pygame.display.set_icon(icon)
clock = pygame.time.Clock()  # 创建一个时钟以便于确保游戏能以指定的FPS运行


class Player(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((50, 40))
        self.image.fill(GREEN)
        self.rect = self.image.get_rect()
        self.rect.centerx = WIDTH/2
        self.rect.bottom = HEIGHT - 10
        self.speedx = 0

    def update(self):
        # any code here will happen every time the game loop updates
        self.speedx = 0
        keystate = pygame.key.get_pressed()
        if keystate[pygame.K_LEFT]:
            self.speedx = -8
        if keystate[pygame.K_RIGHT]:
            self.speedx = 8
        self.rect.x += self.speedx
        if self.rect.right > WIDTH:
            self.rect.right = WIDTH
        if self.rect.left < 0:
            self.rect.left = 0


class Mob(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((30, 40))
        self.image.fill(RED)
        self.rect = self.image.get_rect()
        self.rect.x = random.randrange(WIDTH - self.rect.width)
        self.rect.y = random.randrange(-100, -40)
        self.speedx = random.randrange(-3, 3)
        self.speedy = random.randrange(1, 8)

    def update(self):
        self.rect.x += self.speedx
        self.rect.y += self.speedy
        if self.rect.top > HEIGHT + 10 or self.rect.left < -50 or self.rect.right > WIDTH + 20:
            self.rect.x = random.randrange(WIDTH - self.rect.width)
            self.rect.y = random.randrange(-100, -40)
            self.speedy = random.randrange(1, 8)


all_sprites = pygame.sprite.Group()
mobs = pygame.sprite.Group()
player = Player()
all_sprites.add(player)
for i in range(8):
    m = Mob()
    all_sprites.add(m)
    mobs.add(m)


# Game Loop
running = True


while running:
    # keep loop running at the right speed
    clock.tick(FPS)

    # Process input(events)    # 这是游戏主循环，通过变量running控制，如果需要
    for event in pygame.event.get():
        # check for closing window
        if event.type == pygame.QUIT:
            running = False


    # Update                   # 游戏结束的话直接将running设为False即可
    all_sprites.update()


    # Render(draw)             # 现在还没有确定具体的代码，先用一些基本代码填充，后续再补充
    screen.fill(BLACK)
    all_sprites.draw(screen)
    # *after* drawing everything,flip the display
    pygame.display.flip()



pygame.quit()

项目代码可以查看我的github，网址为
alien-invasion