Pygame游戲開發(fā)之太空射擊實(shí)戰(zhàn)盾牌篇

更新時(shí)間：2022年08月05日 09:46:14 作者：acktomas

相信大多數(shù)8090后都玩過太空射擊游戲，在過去游戲不多的年代太空射擊自然屬于經(jīng)典好玩的一款了，今天我們來(lái)自己動(dòng)手實(shí)現(xiàn)它，在編寫學(xué)習(xí)中回顧過往展望未來(lái)，在本課中，我們將為玩家添加一個(gè)盾牌以及一個(gè)用于顯示盾牌等級(jí)的欄

視頻

本課程的視頻

添加盾牌

現(xiàn)在，我們的玩家被一顆流星擊中就摧毀。這不是很有趣，所以我們要向Player類添加一個(gè)shield屬性，它是0 - 100 的數(shù)字。

class Player(pygame.sprite.Sprite):
    def __init__(self):
        self.speedx = 0
        self.shield = 100

現(xiàn)在，每當(dāng)玩家被流星擊中時(shí)，我們可以從盾牌中減去一點(diǎn)。當(dāng)護(hù)盾達(dá)到0時(shí)，玩家被摧毀。為了讓事情變得更有趣，我們可以通過使用流星的radius屬性使大型流星比微小流星造成更大的傷害。

在下一個(gè)視頻中，我們將為玩家添加一些盾牌，這樣我們就不會(huì)那么容易死亡。

傷害玩家

目前，我們的敵人與玩家碰撞代碼非常簡(jiǎn)單：

    # check to see if a mob hit the player
    hits = pygame.sprite.spritecollide(player, mobs, False, pygame.sprite.collide_circle)
    if hits:
        running = False

我們需要做一些改變：

    # 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
        if player.shield <= 0:
            running = False

我們將 spritecollide函數(shù)的參數(shù)False更改為True，因?yàn)槲覀兿Ｍ餍窃谏渲袝r(shí)將其刪除。如果我們不這樣做，那么流星將繼續(xù)存在，當(dāng)它移動(dòng)時(shí)，下一幀就會(huì)有另一次碰撞，依此類推。此外，我們有可能同時(shí)擊中多顆流星，hits其中可以有多個(gè)項(xiàng)目。我們通過循環(huán)hits，并根據(jù)它的半徑為每次命中扣除一些盾牌。最后，如果玩家的盾牌達(dá)到0，游戲?qū)⒔Y(jié)束。

您可能已經(jīng)注意到的一件事是，由于我們正在刪除任何擊中玩家的敵人，因此，我們正在減少游戲中的敵人總數(shù)。我們希望它保持不變，所以每當(dāng)我們移除一個(gè)敵人時(shí)，我們都需要生成一個(gè)新的敵人。我們是這樣生成原始的敵人，如下所示：

for i in range(8):
    m = Mob()
    all_sprites.add(m)
    mobs.add(m)

但，我們需要生成一個(gè)新的敵人，這是重復(fù)代碼，這是一件壞事。相反，我們將 mob 創(chuàng)建代碼移動(dòng)到一個(gè)函數(shù)中，我們可以在需要時(shí)使用它：

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

現(xiàn)在，我們可以在游戲開始時(shí)，當(dāng)我們射中敵人時(shí)，以及當(dāng)我們需要替換擊中玩家的敵人時(shí)，都可以使用該函數(shù)：

for i in range(8):
    newmob()
# 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()
    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
    newmob()
    if player.shield <= 0:
        running = False

盾牌標(biāo)尺

我們有一個(gè)盾牌的值，我們需要顯示它，但不僅僅是顯示數(shù)字，我們將制作一個(gè)條形圖，顯示盾牌的滿/空：

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)

此函數(shù)的工作方式與我們之前定義的draw_text函數(shù)類似。它將繪制一個(gè)長(zhǎng)為BAR_LENGTH、高為BAR_HEIGHT 的條形，位于(x, y) 該柱并按pct值填充。我們將繪制兩個(gè)矩形：第一個(gè)矩形將是白色輪廓，第二個(gè)矩形是綠色填充部分。我們?cè)谟螒蜓h(huán)的繪制部分添加對(duì)此函數(shù)的調(diào)用：

draw_text(screen, str(score), 18, WIDTH / 2, 10)
draw_shield_bar(screen, 5, 5, player.shield)

現(xiàn)在我們可以看到當(dāng)它下降時(shí)我們剩下多少盾牌：

此部分的完整代碼

# KidsCanCode - Game Development with Pygame video series
# Shmup game - part 9
# Video link: https://www.youtube.com/watch?v=vvgWfNLgK9c
# Player shield
# 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
# 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)
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
    def update(self):
        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
    def shoot(self):
        bullet = Bullet(self.rect.centerx, self.rect.top)
        all_sprites.add(bullet)
        bullets.add(bullet)
        shoot_sound.play()
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()
# 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()
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())
# Load all game sounds
shoot_sound = pygame.mixer.Sound(path.join(snd_dir, 'pew.wav'))
expl_sounds = []
for snd in ['expl3.wav', 'expl6.wav']:
    expl_sounds.append(pygame.mixer.Sound(path.join(snd_dir, snd)))
pygame.mixer.music.load(path.join(snd_dir, 'tgfcoder-FrozenJam-SeamlessLoop.ogg'))
pygame.mixer.music.set_volume(0.4)
all_sprites = pygame.sprite.Group()
mobs = pygame.sprite.Group()
bullets = pygame.sprite.Group()
player = Player()
all_sprites.add(player)
for i in range(8):
    newmob()
score = 0
pygame.mixer.music.play(loops=-1)
# Game loop
running = True
while running:
    # 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
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_SPACE:
                player.shoot()
    # 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()
        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
        newmob()
        if player.shield <= 0:
            running = False
    # 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)
    # *after* drawing everything, flip the display
    pygame.display.flip()
pygame.quit()

第10部分：爆炸

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