太空射击第17课： Game Over （結束）

这是我们“Shmup”项目的第14部分。如果您尚未通读前面的部分，请从第 1 部分开始。在本课中，我们将通过添加“游戏结束”屏幕和再次玩游戏的功能来完成游戏。

视频

您可以在此处观看本课程的视频：

游戏结束

现在，当我们的玩家耗尽生命时，程序会突然结束。这不是很友好，所以我们将制作一个“游戏结束”屏幕，并允许玩家根据需要再次玩游戏。

游戏结束的原因是我们的游戏循环由running标志控制（running标志是一个变量，可以是真或假），我们设置running为False玩家死亡时。相反，我们想要跟踪游戏所处的状态（显示游戏结束或正在播放），我们将创建一个名为game_over 的标志，并将其添加到游戏循环的顶部：

# Game loop
game_over = True
running = True
while running:
    if game_over:
        show_go_screen()

我们稍后会定义show_go_screen()，但我们还需要考虑其他事情。当游戏结束时，我们通过屏幕进入游戏，如果玩家选择再次玩，我们需要重置所有内容 - 分数，流星，玩家的生命值等。现在，我们在游戏循环开始之前设置了这些内容，但现在我们将将它们移动到show_go_screen()之后，以便每当玩家退出该屏幕时，它们就会发生：

# Game loop
game_over = True
running = True
while running:
    if game_over:
        show_go_screen()
        game_over = False
        all_sprites = pygame.sprite.Group()
        mobs = pygame.sprite.Group()
        bullets = pygame.sprite.Group()
        powerups = pygame.sprite.Group()
        player = Player()
        all_sprites.add(player)
        for i in range(8):
            newmob()
        score = 0

我们开始设置game_over为False，因为我们要开始一个新的游戏。然后，我们可以改变当玩家耗尽生命时发生的事情：

# if the player died and the explosion has finished playing
if player.lives == 0 and not death_explosion.alive():
    game_over = True

游戏结束屏幕

现在我们只需要定义show_go_screen做些什么。由于对于此示例，我们只做一个“屏幕”，因此我们只使用游戏的标题，并放置一些有关如何玩游戏的漂亮说明：

def show_go_screen():
    screen.blit(background, background_rect)
    draw_text(screen, "SHMUP!", 64, WIDTH / 2, HEIGHT / 4)
    draw_text(screen, "Arrow keys move, Space to fire", 22,
              WIDTH / 2, HEIGHT / 2)
    draw_text(screen, "Press a key to begin", 18, WIDTH / 2, HEIGHT * 3 / 4)
    pygame.display.flip()
    waiting = True
    while waiting:
        clock.tick(FPS)
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
            if event.type == pygame.KEYUP:
                waiting = False

末尾的 while 循环是我们如何处理“按一个键开始”部分。这有点像一个微型游戏循环，但我们所做的只是检查事件。我们唯一关心的事件是pygame.QUIT ，单击窗口上的 X 时会发生 ，以及按键时发生的事件。你有没有注意到我们没有使用'pygame.KEYDOWN'？

使用KEYUP代替的原因是，当玩家仍然按住一个键时，我们不会启动游戏。他们必须点击并释放才能继续。

这是在屏幕上玩游戏的一种非常简单的方法。还有许多其他方法来处理它，但我们将在后面的教程中讨论这些方法。

结束语

我们有它，你的第一个完整的Pygame游戏！如果你已经坚持了所有这些步骤，那么你就走上了成为一名游戏程序员的道路。

显然，我们可以添加更多内容，例如：

• 难度增加
• 更多道具
• 敌人（反击！）
• 高分制
• 老板级别

您可能还可以想到其他想法。但是，出于本视频的目的，我们将称此游戏完成。在以后的课程中，我们将介绍其他技术，然后您可以返回并将其应用于Shmup。

您可以在此处查看我们所做的其他课程：KidsCanCode 课程和教程

感谢您阅读/观看这些课程！非常感谢您的支持，问题和意见。

此部分的完整代码

# KidsCanCode - Game Development with Pygame video series
# Shmup game - part 14
# Video link: https://www.youtube.com/watch?v=Z2K2Yttvr5g
# Game Over Screen
# Frozen Jam by tgfcoder <https://twitter.com/tgfcoder> licensed under CC-BY-3
# Art from Kenney.nl
import pygame
import random
from os import path

img_dir = path.join(path.dirname(__file__), 'img')
snd_dir = path.join(path.dirname(__file__), 'snd')

WIDTH = 480
HEIGHT = 600
FPS = 60
POWERUP_TIME = 5000

# define colors
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)
YELLOW = (255, 255, 0)

# initialize pygame and create window
pygame.init()
pygame.mixer.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Shmup!")
clock = pygame.time.Clock()

font_name = pygame.font.match_font('arial')
def draw_text(surf, text, size, x, y):
    font = pygame.font.Font(font_name, size)
    text_surface = font.render(text, True, WHITE)
    text_rect = text_surface.get_rect()
    text_rect.midtop = (x, y)
    surf.blit(text_surface, text_rect)

def newmob():
    m = Mob()
    all_sprites.add(m)
    mobs.add(m)

def draw_shield_bar(surf, x, y, pct):
    if pct < 0:
        pct = 0
    BAR_LENGTH = 100
    BAR_HEIGHT = 10
    fill = (pct / 100) * BAR_LENGTH
    outline_rect = pygame.Rect(x, y, BAR_LENGTH, BAR_HEIGHT)
    fill_rect = pygame.Rect(x, y, fill, BAR_HEIGHT)
    pygame.draw.rect(surf, GREEN, fill_rect)
    pygame.draw.rect(surf, WHITE, outline_rect, 2)

def draw_lives(surf, x, y, lives, img):
    for i in range(lives):
        img_rect = img.get_rect()
        img_rect.x = x + 30 * i
        img_rect.y = y
        surf.blit(img, img_rect)

class Player(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.transform.scale(player_img, (50, 38))
        self.image.set_colorkey(BLACK)
        self.rect = self.image.get_rect()
        self.radius = 20
        # pygame.draw.circle(self.image, RED, self.rect.center, self.radius)
        self.rect.centerx = WIDTH / 2
        self.rect.bottom = HEIGHT - 10
        self.speedx = 0
        self.shield = 100
        self.shoot_delay = 250
        self.last_shot = pygame.time.get_ticks()
        self.lives = 3
        self.hidden = False
        self.hide_timer = pygame.time.get_ticks()
        self.power = 1
        self.power_time = pygame.time.get_ticks()

    def update(self):
        # timeout for powerups
        if self.power >= 2 and pygame.time.get_ticks() - self.power_time > POWERUP_TIME:
            self.power -= 1
            self.power_time = pygame.time.get_ticks()

        # unhide if hidden
        if self.hidden and pygame.time.get_ticks() - self.hide_timer > 1000:
            self.hidden = False
            self.rect.centerx = WIDTH / 2
            self.rect.bottom = HEIGHT - 10

        self.speedx = 0
        keystate = pygame.key.get_pressed()
        if keystate[pygame.K_LEFT]:
            self.speedx = -8
        if keystate[pygame.K_RIGHT]:
            self.speedx = 8
        if keystate[pygame.K_SPACE]:
            self.shoot()
        self.rect.x += self.speedx
        if self.rect.right > WIDTH:
            self.rect.right = WIDTH
        if self.rect.left < 0:
            self.rect.left = 0

    def powerup(self):
        self.power += 1
        self.power_time = pygame.time.get_ticks()

    def shoot(self):
        now = pygame.time.get_ticks()
        if now - self.last_shot > self.shoot_delay:
            self.last_shot = now
            if self.power == 1:
                bullet = Bullet(self.rect.centerx, self.rect.top)
                all_sprites.add(bullet)
                bullets.add(bullet)
                shoot_sound.play()
            if self.power >= 2:
                bullet1 = Bullet(self.rect.left, self.rect.centery)
                bullet2 = Bullet(self.rect.right, self.rect.centery)
                all_sprites.add(bullet1)
                all_sprites.add(bullet2)
                bullets.add(bullet1)
                bullets.add(bullet2)
                shoot_sound.play()

    def hide(self):
        # hide the player temporarily
        self.hidden = True
        self.hide_timer = pygame.time.get_ticks()
        self.rect.center = (WIDTH / 2, HEIGHT + 200)

class Mob(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image_orig = random.choice(meteor_images)
        self.image_orig.set_colorkey(BLACK)
        self.image = self.image_orig.copy()
        self.rect = self.image.get_rect()
        self.radius = int(self.rect.width * .85 / 2)
        # pygame.draw.circle(self.image, RED, self.rect.center, self.radius)
        self.rect.x = random.randrange(WIDTH - self.rect.width)
        self.rect.bottom = random.randrange(-80, -20)
        self.speedy = random.randrange(1, 8)
        self.speedx = random.randrange(-3, 3)
        self.rot = 0
        self.rot_speed = random.randrange(-8, 8)
        self.last_update = pygame.time.get_ticks()

    def rotate(self):
        now = pygame.time.get_ticks()
        if now - self.last_update > 50:
            self.last_update = now
            self.rot = (self.rot + self.rot_speed) % 360
            new_image = pygame.transform.rotate(self.image_orig, self.rot)
            old_center = self.rect.center
            self.image = new_image
            self.rect = self.image.get_rect()
            self.rect.center = old_center

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

class Bullet(pygame.sprite.Sprite):
    def __init__(self, x, y):
        pygame.sprite.Sprite.__init__(self)
        self.image = bullet_img
        self.image.set_colorkey(BLACK)
        self.rect = self.image.get_rect()
        self.rect.bottom = y
        self.rect.centerx = x
        self.speedy = -10

    def update(self):
        self.rect.y += self.speedy
        # kill if it moves off the top of the screen
        if self.rect.bottom < 0:
            self.kill()

class Pow(pygame.sprite.Sprite):
    def __init__(self, center):
        pygame.sprite.Sprite.__init__(self)
        self.type = random.choice(['shield', 'gun'])
        self.image = powerup_images[self.type]
        self.image.set_colorkey(BLACK)
        self.rect = self.image.get_rect()
        self.rect.center = center
        self.speedy = 5

    def update(self):
        self.rect.y += self.speedy
        # kill if it moves off the top of the screen
        if self.rect.top > HEIGHT:
            self.kill()

class Explosion(pygame.sprite.Sprite):
    def __init__(self, center, size):
        pygame.sprite.Sprite.__init__(self)
        self.size = size
        self.image = explosion_anim[self.size][0]
        self.rect = self.image.get_rect()
        self.rect.center = center
        self.frame = 0
        self.last_update = pygame.time.get_ticks()
        self.frame_rate = 75

    def update(self):
        now = pygame.time.get_ticks()
        if now - self.last_update > self.frame_rate:
            self.last_update = now
            self.frame += 1
            if self.frame == len(explosion_anim[self.size]):
                self.kill()
            else:
                center = self.rect.center
                self.image = explosion_anim[self.size][self.frame]
                self.rect = self.image.get_rect()
                self.rect.center = center

def show_go_screen():
    screen.blit(background, background_rect)
    draw_text(screen, "SHMUP!", 64, WIDTH / 2, HEIGHT / 4)
    draw_text(screen, "Arrow keys move, Space to fire", 22,
              WIDTH / 2, HEIGHT / 2)
    draw_text(screen, "Press a key to begin", 18, WIDTH / 2, HEIGHT * 3 / 4)
    pygame.display.flip()
    waiting = True
    while waiting:
        clock.tick(FPS)
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
            if event.type == pygame.KEYUP:
                waiting = False

# Load all game graphics
background = pygame.image.load(path.join(img_dir, "starfield.png")).convert()
background_rect = background.get_rect()
player_img = pygame.image.load(path.join(img_dir, "playerShip1_orange.png")).convert()
player_mini_img = pygame.transform.scale(player_img, (25, 19))
player_mini_img.set_colorkey(BLACK)
bullet_img = pygame.image.load(path.join(img_dir, "laserRed16.png")).convert()
meteor_images = []
meteor_list = ['meteorBrown_big1.png', 'meteorBrown_med1.png', 'meteorBrown_med1.png',
               'meteorBrown_med3.png', 'meteorBrown_small1.png', 'meteorBrown_small2.png',
               'meteorBrown_tiny1.png']
for img in meteor_list:
    meteor_images.append(pygame.image.load(path.join(img_dir, img)).convert())
explosion_anim = {
    }
explosion_anim['lg'] = []
explosion_anim['sm'] = []
explosion_anim['player'] = []
for i in range(9):
    filename = 'regularExplosion0{}.png'.format(i)
    img = pygame.image.load(path.join(img_dir, filename)).convert()
    img.set_colorkey(BLACK)
    img_lg = pygame.transform.scale(img, (75, 75))
    explosion_anim['lg'].append(img_lg)
    img_sm = pygame.transform.scale(img, (32, 32))
    explosion_anim['sm'].append(img_sm)
    filename = 'sonicExplosion0{}.png'.format(i)
    img = pygame.image.load(path.join(img_dir, filename)).convert()
    img.set_colorkey(BLACK)
    explosion_anim['player'].append(img)
powerup_images = {
    }
powerup_images['shield'] = pygame.image.load(path.join(img_dir, 'shield_gold.png')).convert()
powerup_images['gun'] = pygame.image.load(path.join(img_dir, 'bolt_gold.png')).convert()


# Load all game sounds
shoot_sound = pygame.mixer.Sound(path.join(snd_dir, 'pew.wav'))
shield_sound = pygame.mixer.Sound(path.join(snd_dir, 'pow4.wav'))
power_sound = pygame.mixer.Sound(path.join(snd_dir, 'pow5.wav'))
expl_sounds = []
for snd in ['expl3.wav', 'expl6.wav']:
    expl_sounds.append(pygame.mixer.Sound(path.join(snd_dir, snd)))
player_die_sound = pygame.mixer.Sound(path.join(snd_dir, 'rumble1.ogg'))
pygame.mixer.music.load(path.join(snd_dir, 'tgfcoder-FrozenJam-SeamlessLoop.ogg'))
pygame.mixer.music.set_volume(0.4)

pygame.mixer.music.play(loops=-1)
# Game loop
game_over = True
running = True
while running:
    if game_over:
        show_go_screen()
        game_over = False
        all_sprites = pygame.sprite.Group()
        mobs = pygame.sprite.Group()
        bullets = pygame.sprite.Group()
        powerups = pygame.sprite.Group()
        player = Player()
        all_sprites.add(player)
        for i in range(8):
            newmob()
        score = 0

    # keep loop running at the right speed
    clock.tick(FPS)
    # Process input (events)
    for event in pygame.event.get():
        # check for closing window
        if event.type == pygame.QUIT:
            running = False

    # Update
    all_sprites.update()

    # check to see if a bullet hit a mob
    hits = pygame.sprite.groupcollide(mobs, bullets, True, True)
    for hit in hits:
        score += 50 - hit.radius
        random.choice(expl_sounds).play()
        expl = Explosion(hit.rect.center, 'lg')
        all_sprites.add(expl)
        if random.random() > 0.9:
            pow = Pow(hit.rect.center)
            all_sprites.add(pow)
            powerups.add(pow)
        newmob()

    # check to see if a mob hit the player
    hits = pygame.sprite.spritecollide(player, mobs, True, pygame.sprite.collide_circle)
    for hit in hits:
        player.shield -= hit.radius * 2
        expl = Explosion(hit.rect.center, 'sm')
        all_sprites.add(expl)
        newmob()
        if player.shield <= 0:
            player_die_sound.play()
            death_explosion = Explosion(player.rect.center, 'player')
            all_sprites.add(death_explosion)
            player.hide()
            player.lives -= 1
            player.shield = 100

    # check to see if player hit a powerup
    hits = pygame.sprite.spritecollide(player, powerups, True)
    for hit in hits:
        if hit.type == 'shield':
            player.shield += random.randrange(10, 30)
            shield_sound.play()
            if player.shield >= 100:
                player.shield = 100
        if hit.type == 'gun':
            player.powerup()
            power_sound.play()

    # if the player died and the explosion has finished playing
    if player.lives == 0 and not death_explosion.alive():
        game_over = True

    # Draw / render
    screen.fill(BLACK)
    screen.blit(background, background_rect)
    all_sprites.draw(screen)
    draw_text(screen, str(score), 18, WIDTH / 2, 10)
    draw_shield_bar(screen, 5, 5, player.shield)
    draw_lives(screen, WIDTH - 100, 5, player.lives, player_mini_img)
    # *after* drawing everything, flip the display
    pygame.display.flip()

pygame.quit()