墙壁挡住骑士

本课属于 Coddy Pygame 学习旅程的“项目”单元。第 24 课，共 33 课。

骑士使用方向键移动，每帧移动 3 个像素。墙会挡住他，就像《Moss Caves》中的平台一样：沿 x 轴移动，把他从任何重叠的墙中推出，然后沿 y 轴重复同样的操作。一次只处理一个轴，就能知道他撞到了哪一侧。

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

像在《Catch the Blocks》中那样，每帧读取方向键状态并存入 dx 和 dy，然后传入房间的墙：

keys = pygame.key.get_pressed()
dx = 0
dy = 0
if keys[pygame.K_LEFT]:
    dx = -3
# 向右、向上和向下也用同样的方法处理
knight.move(dx, dy, room.walls)

挑战

困难

让骑士行走，并在墙壁处停下。

为 Knight 添加上面的 move(dx, dy, blocks) 方法。
每一帧，按左键时将 dx 设为 -3，按右键时设为 3；按上键时将 dy 设为 -3，按下键时设为 3；其他情况下设为 0。
然后调用 knight.move(dx, dy, room.walls)。

按“开始”，让骑士走向墙壁：骑士会停在墙边。然后按“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)
        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


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


room = Room(MAP)
knight = Knight(room.start)

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    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)
    draw(knight.image, knight.rect)
    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