巡逻的史莱姆
本课属于 Coddy Pygame 学习旅程的“项目”单元。第 26 课，共 33 课。
地图上的每个 S 都是一个史莱姆，它会沿着所在行滑动，每帧移动 2 像素，碰到墙壁时就会掉头。
Enemy 精灵会保存自己的速度 dx 和 dy，因此之后可以用同一个类创建上下移动的怪物。它的 update 方法会移动精灵，如果它此时与方块重叠，就会退回并反向移动：
def update(self, blocks):
self.rect.x += self.dx
self.rect.y += self.dy
if self.rect.collidelist(blocks) != -1:
self.rect.x -= self.dx
self.rect.y -= self.dy
self.dx = -self.dx
self.dy = -self.dyrect.collidelist(rects) 会返回列表中第一个与之重叠的 Rect 的索引；如果没有重叠，则返回 -1。
史莱姆位于一个精灵组中，即 room.enemies。room.enemies.update(room.walls + [room.door]) 会将这个列表传给每只史莱姆并调用它的 update 方法。门始终在列表中，因此史莱姆不会从打开的门溜出去。
random.choice([-2, 2]) 会让每只史莱姆一开始向左或向右移动，因此每次游戏都不一样。
挑战
中等添加在房间里巡逻的史莱姆。
- 添加
import random和上面的Enemy类：__init__(self, image, rect, dx, dy)保存这四个值，另外还要添加update。 - 在
Room中，创建self.enemies = pygame.sprite.Group()；遇到S时，添加Enemy(slime_img, cell_rect(col, row), speed, 0)，并设置speed = random.choice([-2, 2])。 - 在门的处理之后，调用
room.enemies.update(room.walls + [room.door])；在绘制骑士之前绘制敌人。
按“开始”：史莱姆会沿着所在行巡逻。然后点击“检查”。
亲手试试
import pygame
TILE = 48
MAP = [
"##############",
"#............#",
"#.P......K...#",
"#............#",
"#....##......D",
"#....##......#",
"##.#######.###",
"#............#",
"#...S....H...#",
"##############",
]
pygame.init()
screen = pygame.display.set_mode((672, 480))
pygame.display.set_caption("Rune Keep")
clock = pygame.time.Clock()
font = pygame.font.Font("assets/fonts/pixel.ttf", 32)
def load(name):
return pygame.image.load("assets/images/" + name).convert_alpha()
floor_img = load("floor.png")
wall_img = load("wall.png")
knight_img = load("knight.png")
door_img = load("dungeon_door.png")
key_img = load("key.png")
slime_img = load("slime.png")
spider_img = load("spider.png")
heart_img = load("heart.png")
empty_img = load("heart_empty.png")
sword_img = load("sword.png")
potion_img = load("potion_red.png")
def draw(image, rect):
screen.blit(image, image.get_rect(center=rect.center))
def cell_rect(col, row):
rect = pygame.Rect(0, 0, 32, 32)
rect.center = (col * TILE + 24, row * TILE + 24)
return rect
class Room:
def __init__(self, lines):
self.walls = []
self.start = (72, 72)
self.has_key = False
self.door_open = False
for row, line in enumerate(lines):
for col, char in enumerate(line):
if char == "#":
self.walls.append(pygame.Rect(col * TILE, row * TILE, TILE, TILE))
elif char == "P":
self.start = cell_rect(col, row).center
elif char == "K":
self.key = cell_rect(col, row)
elif char == "D":
self.door = pygame.Rect(col * TILE, row * TILE, TILE, TILE)
def blocks(self):
if self.door_open:
return self.walls
return self.walls + [self.door]
class Knight(pygame.sprite.Sprite):
def __init__(self, center):
super().__init__()
self.image = knight_img
self.rect = pygame.Rect(0, 0, 32, 32)
self.rect.center = center
def move(self, dx, dy, blocks):
self.rect.x += dx
for block in blocks:
if self.rect.colliderect(block):
if dx > 0:
self.rect.right = block.left
elif dx < 0:
self.rect.left = block.right
self.rect.y += dy
for block in blocks:
if self.rect.colliderect(block):
if dy > 0:
self.rect.bottom = block.top
elif dy < 0:
self.rect.top = block.bottom
room = Room(MAP)
knight = Knight(room.start)
running = True
while running:
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
keys = pygame.key.get_pressed()
dx = 0
dy = 0
if keys[pygame.K_LEFT]:
dx = -3
if keys[pygame.K_RIGHT]:
dx = 3
if keys[pygame.K_UP]:
dy = -3
if keys[pygame.K_DOWN]:
dy = 3
knight.move(dx, dy, room.blocks())
knight.rect.clamp_ip(screen.get_rect())
if not room.has_key and knight.rect.colliderect(room.key):
room.has_key = True
if room.has_key and knight.rect.inflate(8, 8).colliderect(room.door):
room.door_open = True
for row in range(10):
for col in range(14):
screen.blit(floor_img, (col * TILE, row * TILE))
for wall in room.walls:
screen.blit(wall_img, wall)
if not room.door_open:
screen.blit(door_img, room.door)
if not room.has_key:
draw(key_img, room.key)
draw(knight.image, knight.rect)
if room.has_key:
screen.blit(key_img, (136, 6))
pygame.display.flip()
clock.tick(60)
pygame.quit()
项目中的所有课
自己练习： Pygame 在线编辑器