天空跑者的菜单

本课属于 Coddy Pygame 学习旅程的“游戏规则”单元。第 29 课，共 30 课。

Sky Runner 从这个单元获取规则，首先是菜单。新游戏需要将所有内容恢复到初始状态，所以把这些操作放进 reset()：创建一个新的 runner、一个空的组，重置速度和分数，并重新启动两个计时器。

现在，空格键根据状态执行两种操作：

if state == "play":
    runner.jump()
elif state == "menu":
    reset()
    state = "play"

菜单需要两行居中的文字，游戏结束画面需要三行，所以可以用一个小函数在 x 坐标 320 处居中绘制一行文字：

def show(text, text_font, y):
    picture = text_font.render(text, True, INK)
    screen.blit(picture, picture.get_rect(center=(320, y)))

分数属于一局游戏，所以只有游戏开始后才显示，不要在菜单上显示。

挑战

中等

为 Sky Runner 添加菜单。

编写 reset()，重置 runner、group、speed、score 和两个计时器；在循环前调用它，并设置 state = "menu"。
在菜单中，使用 show() 以 big_font 显示 Sky Runner 和 Press Space to start；仅在菜单外显示分数。
在菜单中按 Space 会调用 reset() 并设置 state = "play"。

按“开始”：按 Space 开始游戏。然后按“检查”。

亲手试试

import random
import pygame

pygame.init()
screen = pygame.display.set_mode((640, 320))
pygame.display.set_caption("Sky Runner")
clock = pygame.time.Clock()
font = pygame.font.Font("assets/fonts/pixel.ttf", 32)

SKY = (140, 200, 240)
GROUND = (90, 160, 80)
GROUND_Y = 260
GRAVITY = 1
SPAWN = pygame.USEREVENT + 1
POINT = pygame.USEREVENT + 2


class Runner(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.frames = [
            pygame.image.load("assets/images/player.png").convert_alpha(),
            pygame.image.load("assets/images/player_walk.png").convert_alpha(),
        ]
        self.image = self.frames[0]
        self.step = 0
        self.rect = self.image.get_rect(midbottom=(100, GROUND_Y))
        self.vy = 0

    def jump(self):
        if self.rect.bottom == GROUND_Y:
            self.vy = -16

    def update(self):
        self.vy += GRAVITY
        self.rect.y += self.vy
        if self.rect.bottom >= GROUND_Y:
            self.rect.bottom = GROUND_Y
            self.vy = 0
        if self.rect.bottom == GROUND_Y:
            self.step += 1
            self.image = self.frames[self.step // 8 % 2]
        else:
            self.image = self.frames[1]


class Obstacle(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = random.choice(obstacle_images)
        self.rect = self.image.get_rect(midbottom=(664, GROUND_Y))

    def update(self):
        self.rect.x -= speed
        if self.rect.right < 0:
            self.kill()


obstacle_images = [
    pygame.image.load("assets/images/spike_ball.png").convert_alpha(),
    pygame.image.load("assets/images/blob.png").convert_alpha(),
]
runner = Runner()
obstacles = pygame.sprite.Group()
speed = 6
pygame.time.set_timer(SPAWN, 1500)
pygame.time.set_timer(POINT, 100)
score = 0
state = "play"

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        if event.type == pygame.KEYDOWN and event.key in (pygame.K_SPACE, pygame.K_UP):
            if state == "play":
                runner.jump()
        if event.type == SPAWN and state == "play":
            obstacles.add(Obstacle())
            pygame.time.set_timer(SPAWN, random.randint(1000, 2000))
        if event.type == POINT and state == "play":
            score += 1

    if state == "play":
        speed = min(14, 6 + score // 100)
        runner.update()
        obstacles.update()
        if pygame.sprite.spritecollideany(runner, obstacles, pygame.sprite.collide_mask):
            state = "over"

    screen.fill(SKY)
    pygame.draw.rect(screen, GROUND, (0, GROUND_Y, 640, 60))
    screen.blit(runner.image, runner.rect)
    obstacles.draw(screen)
    score_text = font.render(f"{score:05}", True, (40, 50, 80))
    screen.blit(score_text, score_text.get_rect(topright=(630, 10)))
    if state == "over":
        message = font.render("Game over", True, (40, 50, 80))
        screen.blit(message, message.get_rect(center=(320, 140)))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()

游戏规则中的所有课

自己练习： Pygame 在线编辑器