新纪录

本课属于 Coddy Pygame 学习旅程的“游戏规则”单元。第 22 课，共 30 课。

打破自己的最佳成绩时，正是庆祝的时刻。游戏应该在结束画面上显示这一点，而且只有打破纪录时才显示。

两行代码的顺序决定了结果。先将分数与之前的最佳成绩比较，再更新最佳成绩：

new_record = score > best
best = max(best, score)

如果交换两行，比较时 best 已经保存了当前分数，所以 score > best 永远不成立。

score > best 是一个比较表达式，因此 new_record 的值是 True 或 False。游戏结束画面会检查它：

if new_record:
    record = font.render("New record!", True, (255, 220, 90))
    screen.blit(record, record.get_rect(center=(240, 110)))

分数等于最佳成绩不算打破纪录，这就是为什么要用 >，而不是 >=。

挑战

中等

庆祝获得新的最高分。

游戏结束时，在更新 best 之前设置 new_record = score > best。
在游戏结束画面中，当 new_record 为 true 时，在 (240, 110) 位置居中显示 New record!，颜色为 (255, 220, 90)。

点击“开始”，并在输掉之前得分：New record! 会以金色显示。然后点击“检查”。

亲手试试

import random
import pygame

pygame.init()
screen = pygame.display.set_mode((480, 360))
pygame.display.set_caption("Meteor Dodge")
clock = pygame.time.Clock()
heart = pygame.image.load("assets/images/heart.png").convert_alpha()
heart_empty = pygame.image.load("assets/images/heart_empty.png").convert_alpha()
font = pygame.font.Font("assets/fonts/pixel.ttf", 24)
big_font = pygame.font.Font("assets/fonts/pixel.ttf", 48)
WHITE = (240, 240, 240)
PLATE = (60, 60, 90)
POINT = pygame.USEREVENT + 1
SPAWN = pygame.USEREVENT + 2


def reset():
    global player, rocks, score, lives
    player = pygame.Rect(220, 300, 40, 40)
    rocks = []
    score = 0
    lives = 3
    pygame.time.set_timer(POINT, 1000)
    pygame.time.set_timer(SPAWN, 800)


def load_best():
    try:
        with open("highscore.txt") as file:
            return int(file.read())
    except FileNotFoundError:
        return 0


def draw_menu():
    screen.fill((30, 30, 46))
    title = big_font.render("Meteor Dodge", True, WHITE)
    title_rect = title.get_rect(center=(240, 140))
    pygame.draw.rect(screen, PLATE, title_rect.inflate(24, 12))
    screen.blit(title, title_rect)
    hint = font.render("Press Enter to play", True, WHITE)
    screen.blit(hint, hint.get_rect(center=(240, 200)))


def draw_game():
    screen.fill((30, 30, 46))
    pygame.draw.rect(screen, (255, 196, 0), player)
    for rock in rocks:
        pygame.draw.rect(screen, (235, 80, 80), rock)
    score_text = font.render(f"{score:05}", True, WHITE)
    score_rect = score_text.get_rect(topright=(470, 10))
    pygame.draw.rect(screen, PLATE, score_rect.inflate(12, 8))
    screen.blit(score_text, score_rect)
    for i in range(3):
        if i < lives:
            screen.blit(heart, (10 + i * 40, 10))
        else:
            screen.blit(heart_empty, (10 + i * 40, 10))


def play_frame():
    global rocks, lives, state, best
    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT]:
        player.x -= 6
    if keys[pygame.K_RIGHT]:
        player.x += 6
    player.clamp_ip(screen.get_rect())

    kept = []
    for rock in rocks:
        rock.y += 3
        if rock.colliderect(player):
            lives -= 1
        elif rock.top <= 360:
            kept.append(rock)
    rocks = kept
    if lives <= 0:
        state = "over"
        best = max(best, score)
        with open("highscore.txt", "w") as file:
            file.write(str(best))
    draw_game()


def draw_over():
    draw_game()
    message = big_font.render("Game over", True, WHITE)
    screen.blit(message, message.get_rect(center=(240, 160)))
    hint = font.render("Press R to play again", True, WHITE)
    screen.blit(hint, hint.get_rect(center=(240, 200)))
    best_text = font.render(f"Best: {best}", True, WHITE)
    screen.blit(best_text, best_text.get_rect(center=(240, 240)))


reset()
state = "menu"
best = load_best()

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        if event.type == POINT and state == "play":
            score += 1
        if event.type == SPAWN and state == "play":
            rocks.append(pygame.Rect(random.randint(0, 456), -24, 24, 24))
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_RETURN and state == "menu":
                reset()
                state = "play"
            elif event.key == pygame.K_r and state == "over":
                reset()
                state = "play"

    if state == "menu":
        draw_menu()
    elif state == "play":
        play_frame()
    else:
        draw_over()
    pygame.display.flip()
    clock.tick(60)

pygame.quit()

自我测试

这节课包含一个小测验。开始学习即可作答，并记录你的进度。

游戏规则中的所有课

自己练习： Pygame 在线编辑器