来自地图的敌人

本课属于 Coddy Pygame 学习旅程的“游戏世界”单元。第 27 课，共 36 课。

这些 blob 的位置通过代码中的数字设置，关卡里的其他内容则来自地图。也把它们放进地图里：E 表示敌人站在该格子上。

elif char == "E":
    blobs.add(Blob((col * TILE + TILE // 2, row * TILE + TILE)))

(col * TILE + TILE // 2, row * TILE + TILE) 是该格子的底部中点，也就是玩家的起始位置。blob 的 Rect 会把它的底部中点放在那里，因此它会站在 E 下方的地面上。在循环之前创建这个组，这样循环就能向其中添加内容。

现在，设计关卡只需要输入字符：移动一个 E，blob 就会跟着移动；添加一个 E，就会多出一个 blob。把每个 E 都放在下方有地面的格子上，否则 blob 会立刻转向并停在原地。

挑战

简单

根据地图放置 blob 怪物。

在地图循环之前创建 blobs = pygame.sprite.Group()。
对于每个 E，将 Blob((col * TILE + TILE // 2, row * TILE + TILE)) 添加到 blobs。
删除在固定位置创建两个 blob 怪物的那一行。

按下“开始”：地图上每个 E 的位置都会有一个 blob 怪物来回巡逻。然后点击“检查”。

亲手试试

import pygame

TILE = 36
SPEED = 4
GRAVITY = 1
JUMP = -15
MAX_FALL = 12

LEVEL = [
    "................",
    "................",
    "................",
    "...........E....",
    "..........####..",
    "....E...........",
    "...####.........",
    "................",
    "#.P.........E..#",
    "################",
]

pygame.init()
screen = pygame.display.set_mode((576, 360))
pygame.display.set_caption("Enemies From the Map")
clock = pygame.time.Clock()

background = pygame.image.load("assets/backgrounds/clouds.png").convert_alpha()
block_img = pygame.image.load("assets/images/block.png").convert_alpha()
player_img = pygame.image.load("assets/images/player.png").convert_alpha()
blob_img = pygame.image.load("assets/images/blob.png").convert_alpha()
blob_walk_img = pygame.image.load("assets/images/blob_walk.png").convert_alpha()


class Blob(pygame.sprite.Sprite):
    def __init__(self, midbottom):
        super().__init__()
        self.image = blob_img
        self.rect = pygame.Rect(0, 0, 30, 26)
        self.rect.midbottom = midbottom
        self.direction = 1
        self.frames = [blob_img, blob_walk_img]
        self.timer = 0

    def update(self):
        self.timer += 1
        self.image = self.frames[self.timer // 10 % 2]
        self.rect.x += self.direction
        if self.direction > 0:
            ahead = self.rect.right
        else:
            ahead = self.rect.left - 1
        hit_wall = any(self.rect.colliderect(wall) for wall in walls)
        ground_ahead = any(wall.collidepoint(ahead, self.rect.bottom) for wall in walls)
        if hit_wall or not ground_ahead:
            self.rect.x -= self.direction
            self.direction = -self.direction

walls = []
for row, line in enumerate(LEVEL):
    for col, char in enumerate(line):
        if char == "#":
            walls.append(pygame.Rect(col * TILE, row * TILE, TILE, TILE))
        elif char == "P":
            start = (col * TILE + TILE // 2, row * TILE + TILE)

blobs = pygame.sprite.Group(Blob((432, 144)), Blob((432, 324)))
player = player_img.get_rect(midbottom=start)
vel_y = 0
on_ground = False

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN and event.key in (pygame.K_SPACE, pygame.K_UP):
            if on_ground:
                vel_y = JUMP
        elif event.type == pygame.KEYUP and event.key in (pygame.K_SPACE, pygame.K_UP):
            if vel_y < -4:
                vel_y = -4

    keys = pygame.key.get_pressed()
    dx = 0
    if keys[pygame.K_LEFT]:
        dx -= SPEED
    if keys[pygame.K_RIGHT]:
        dx += SPEED

    player.x += dx
    for wall in walls:
        if player.colliderect(wall):
            if dx > 0:
                player.right = wall.left
            elif dx < 0:
                player.left = wall.right

    vel_y = min(vel_y + GRAVITY, MAX_FALL)
    player.y += vel_y
    on_ground = False
    for wall in walls:
        if player.colliderect(wall):
            if vel_y > 0:
                player.bottom = wall.top
                on_ground = True
            elif vel_y < 0:
                player.top = wall.bottom
            vel_y = 0

    blobs.update()

    for blob in blobs:
        if player.colliderect(blob.rect):
            if vel_y > 0 and player.bottom < blob.rect.centery:
                blob.kill()
                vel_y = -8
            else:
                player.midbottom = start
                vel_y = 0

    for y in range(0, 360, 72):
        for x in range(0, 576, 72):
            screen.blit(background, (x, y))
    for wall in walls:
        screen.blit(block_img, wall)
    for blob in blobs:
        screen.blit(blob.image, blob.image.get_rect(midbottom=blob.rect.midbottom))
    screen.blit(player_img, player)
    pygame.display.flip()
    clock.tick(60)

pygame.quit()