普通还是困难
本课属于 Coddy Pygame 学习旅程的“游戏规则”单元。第 17 课，共 30 课。
让玩家在游戏开始前选择难度。菜单显示两个选项，按箭头键选择：
elif event.key == pygame.K_LEFT and state == "menu":
difficulty = "normal"
elif event.key == pygame.K_RIGHT and state == "menu":
difficulty = "hard"游戏进行时也用这两个箭头键移动玩家。检查 state == "menu"，可以区分这两种用途。
菜单会标出选中的选项，让玩家知道按 Enter 会开始哪个难度：
if difficulty == "normal":
normal, hard = "> Normal <", "Hard"
else:
normal, hard = "Normal", "> Hard <"然后，游戏会在设置数值的位置读取 difficulty。在困难模式下，岩石的初始速度是每帧 6 像素，而不是 3 像素：
if difficulty == "normal":
speed = 3 + seconds // 5
else:
speed = 6 + seconds // 5在循环开始前设置一次 difficulty = "normal"，不要在 reset() 中设置，这样按 R 就能保留所选难度。
挑战
中等让玩家选择普通或困难模式。
- 在循环之前设置
difficulty = "normal"；在菜单中，按 Left 设置为"normal"，按 Right 设置为"hard"。 - 将选项居中放在 (160, 260) 和 (320, 260)：
> Normal <和Hard，或Normal和> Hard <。 - 岩石在普通模式下每帧移动 3 像素，在困难模式下每帧移动 6 像素，每过 5 秒再增加 1 像素。
按“运行”，然后按 Right：困难模式会被选中。然后按“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, start_time
player = pygame.Rect(220, 300, 40, 40)
rocks = []
score = 0
lives = 3
start_time = pygame.time.get_ticks()
pygame.time.set_timer(POINT, 1000)
pygame.time.set_timer(SPAWN, 1000)
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
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())
seconds = (pygame.time.get_ticks() - start_time) // 1000
speed = 3 + seconds // 5
kept = []
for rock in rocks:
rock.y += speed
if rock.colliderect(player):
lives -= 1
elif rock.top <= 360:
kept.append(rock)
rocks = kept
if lives <= 0:
state = "over"
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)))
reset()
state = "menu"
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))
seconds = (pygame.time.get_ticks() - start_time) // 1000
interval = max(400, 1000 - seconds * 60)
pygame.time.set_timer(SPAWN, interval)
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()
游戏规则中的所有课
自己练习： Pygame 在线编辑器