Gemas

Lección 13 de 20 del curso Proyecto con Pygame: Defiende la fortaleza de Coddy.

Cada monstruo que cae deja caer una gema donde estaba. Las gemas son lo que hace más fuerte al caballero: recogerlas le da experiencia, xp.

Las gemas cercanas al caballero vuelan hacia él, así que el jugador no tiene que caminar sobre cada una. move_towards_ip(target, 6) mueve un Vector2 6 píxeles hacia un punto, y nunca lo sobrepasa:

def update(self, knight):
    target = pygame.Vector2(knight.rect.center)
    if self.pos.distance_to(target) < knight.magnet:
        self.pos.move_towards_ip(target, 6)
    self.rect.center = self.pos

La distancia a la que las gemas empiezan a volar es el magnet del caballero, 80 píxeles al principio. Un monstruo puede caer sobre el muro, donde el caballero no puede caminar, así que una gema nueva se mueve al patio con self.rect.clamp_ip(courtyard) antes de tomar su pos de su rectángulo. spritecollide(sprite, group, True) devuelve todos los sprites del grupo que toca, y True también los elimina del grupo: una línea recoge todas las gemas sobre las que se encuentra el caballero.

Desafío

Intermedio

Carga gem.png como gem_img y gem_sound = sound("coin.ogg"). Dale al caballero magnet = 80.
Escribe class Gem(pygame.sprite.Sprite): un rect de 24 por 24 centrado en el punto que recibe y limitado al patio, pos como Vector2 del centro del rect, y el update anterior.
En Night: self.gems (un Group) y self.xp = 0. Cuando un monstruo cae, añade Gem(monster.pos).
Escribe collect(self): cada gema que toca el caballero se elimina y otorga 1 xp y gem_sound. En update, self.gems.update(self.knight) después de que se muevan los proyectiles, y self.collect() después de hurt_monsters.
Dibuja las gemas primero, justo después del fondo.

Pruébalo tú mismo

import random
import pygame

WIDTH, HEIGHT = 720, 480
TILE = 48
NIGHT = 60 * 60 * 4
WAVES = [
    ["slime"],
    ["slime", "bat"],
    ["slime", "bat", "spider"],
    ["bat", "spider"],
    ["slime", "spider", "ghost"],
    ["bat", "spider", "ghost"],
    ["spider", "ghost"],
    ["bat", "ghost"],
]
WHITE = (240, 240, 240)
BOLT = (120, 200, 255)

pygame.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Hold the Keep")
clock = pygame.time.Clock()
font = pygame.font.Font("assets/fonts/pixel.ttf", 24)
big_font = pygame.font.Font("assets/fonts/pixel.ttf", 48)


def load(name):
    return pygame.image.load("assets/images/" + name).convert_alpha()


def sound(name):
    return pygame.mixer.Sound("assets/sounds/" + name)


def whiten(image):
    white = image.copy()
    white.fill((255, 255, 255), special_flags=pygame.BLEND_RGB_MAX)
    return white


floor_img = load("floor.png")
wall_img = load("wall.png")
knight_img = load("knight.png")
axe_img = load("axe.png")
heart_img = load("heart.png")
empty_img = load("heart_empty.png")
MONSTERS = {
    "slime": {"image": load("slime.png"), "speed": 1.0, "hp": 1},
    "bat": {"image": load("dungeon_bat.png"), "speed": 1.6, "hp": 1},
    "spider": {"image": load("spider.png"), "speed": 1.2, "hp": 3},
    "ghost": {"image": load("ghost.png"), "speed": 0.8, "hp": 4},
}
hit_sound = sound("hit.ogg")
hurt_sound = sound("thud.ogg")

courtyard = pygame.Rect(TILE, TILE, WIDTH - 2 * TILE, HEIGHT - 2 * TILE)
background = pygame.Surface((WIDTH, HEIGHT))
for row in range(HEIGHT // TILE):
    for col in range(WIDTH // TILE):
        x = col * TILE
        y = row * TILE
        if courtyard.collidepoint(x, y):
            background.blit(floor_img, (x, y))
        else:
            background.blit(wall_img, (x, y))


def draw(image, center):
    screen.blit(image, image.get_rect(center=center))


def clock_text(frames):
    seconds = frames // 60
    return f"{seconds // 60}:{seconds % 60:02d}"


def edge_point():
    side = random.randint(0, 3)
    if side == 0:
        return (random.randint(0, WIDTH), -24)
    if side == 1:
        return (random.randint(0, WIDTH), HEIGHT + 24)
    if side == 2:
        return (-24, random.randint(0, HEIGHT))
    return (WIDTH + 24, random.randint(0, HEIGHT))


class Knight(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = knight_img
        self.rect = pygame.Rect(0, 0, 24, 24)
        self.rect.center = courtyard.center
        self.speed = 3
        self.hearts = 5
        self.max_hearts = 5
        self.hurt = 0
        self.bolt_wait = 30
        self.bolt_damage = 1
        self.axes = 1

    def move(self, keys):
        if keys[pygame.K_LEFT]:
            self.rect.x -= self.speed
        if keys[pygame.K_RIGHT]:
            self.rect.x += self.speed
        if keys[pygame.K_UP]:
            self.rect.y -= self.speed
        if keys[pygame.K_DOWN]:
            self.rect.y += self.speed
        self.rect.clamp_ip(courtyard)


class Monster(pygame.sprite.Sprite):
    def __init__(self, kind, pos):
        super().__init__()
        self.kind = kind
        self.image = MONSTERS[kind]["image"]
        self.speed = MONSTERS[kind]["speed"]
        self.hp = MONSTERS[kind]["hp"]
        self.axe_wait = 0
        self.flash = 0
        self.pos = pygame.Vector2(pos)
        self.rect = pygame.Rect(0, 0, 28, 28)
        self.rect.center = self.pos

    def update(self, target):
        step = pygame.Vector2(target) - self.pos
        if step.length() > 0:
            self.pos += step.normalize() * self.speed
        self.rect.center = self.pos
        if self.axe_wait > 0:
            self.axe_wait -= 1
        if self.flash > 0:
            self.flash -= 1

    def hit(self, damage):
        self.hp -= damage
        self.flash = 6
        hit_sound.play()


class Bolt(pygame.sprite.Sprite):
    def __init__(self, start, target, damage):
        super().__init__()
        self.pos = pygame.Vector2(start)
        step = pygame.Vector2(target) - self.pos
        if step.length() == 0:
            step = pygame.Vector2(1, 0)
        self.velocity = step.normalize() * 7
        self.damage = damage
        self.rect = pygame.Rect(0, 0, 10, 10)
        self.rect.center = self.pos

    def update(self):
        self.pos += self.velocity
        self.rect.center = self.pos
        if not screen.get_rect().colliderect(self.rect):
            self.kill()


class Night:
    def __init__(self):
        self.knight = Knight()
        self.time = 0
        self.monsters = pygame.sprite.Group()
        self.bolts = pygame.sprite.Group()
        self.bolt_timer = 0
        self.spin = 0
        self.state = "playing"

    def wave(self):
        return min(len(WAVES), self.time * len(WAVES) // NIGHT + 1)

    def spawn(self):
        wave = self.wave()
        if self.time % max(16, 46 - wave * 5) == 0:
            kind = random.choice(WAVES[wave - 1])
            self.monsters.add(Monster(kind, edge_point()))

    def nearest(self):
        point = pygame.Vector2(self.knight.rect.center)
        best = None
        for monster in self.monsters:
            if best is None or point.distance_to(monster.pos) < point.distance_to(best.pos):
                best = monster
        return best

    def shoot(self):
        self.bolt_timer += 1
        target = self.nearest()
        if self.bolt_timer >= self.knight.bolt_wait and target is not None:
            self.bolt_timer = 0
            bolt = Bolt(self.knight.rect.center, target.pos, self.knight.bolt_damage)
            self.bolts.add(bolt)

    def axe_spots(self):
        spots = []
        for i in range(self.knight.axes):
            angle = self.spin + i * 360 / self.knight.axes
            offset = pygame.Vector2(70, 0).rotate(angle)
            spots.append(pygame.Vector2(self.knight.rect.center) + offset)
        return spots

    def hurt_monsters(self):
        for bolt in self.bolts:
            target = pygame.sprite.spritecollideany(bolt, self.monsters)
            if target is not None:
                target.hit(bolt.damage)
                bolt.kill()
        for spot in self.axe_spots():
            blade = pygame.Rect(0, 0, 36, 36)
            blade.center = spot
            for monster in self.monsters:
                if monster.axe_wait == 0 and blade.colliderect(monster.rect):
                    monster.hit(1)
                    monster.axe_wait = 20
        for monster in list(self.monsters):
            if monster.hp <= 0:
                monster.kill()

    def take_hits(self):
        knight = self.knight
        if knight.hurt > 0:
            knight.hurt -= 1
        elif pygame.sprite.spritecollideany(knight, self.monsters):
            knight.hearts -= 1
            knight.hurt = 75
            hurt_sound.play()
            if knight.hearts <= 0:
                self.state = "lost"

    def update(self, keys):
        self.time += 1
        self.spin = (self.spin + 4) % 360
        self.knight.move(keys)
        self.spawn()
        self.monsters.update(self.knight.rect.center)
        self.bolts.update()
        self.shoot()
        self.hurt_monsters()
        self.take_hits()


night = Night()

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

    if night.state == "playing":
        night.update(pygame.key.get_pressed())

    screen.blit(background, (0, 0))
    knight = night.knight
    for monster in night.monsters:
        if monster.flash > 0:
            draw(whiten(monster.image), monster.rect.center)
        else:
            draw(monster.image, monster.rect.center)
    if knight.hurt % 10 < 5:
        draw(knight.image, knight.rect.center)
    for spot in night.axe_spots():
        draw(pygame.transform.rotate(axe_img, -night.spin * 3), spot)
    for bolt in night.bolts:
        pygame.draw.circle(screen, BOLT, bolt.rect.center, 5)
    for i in range(knight.max_hearts):
        if i < knight.hearts:
            screen.blit(heart_img, (8 + i * 34, 6))
        else:
            screen.blit(empty_img, (8 + i * 34, 6))
    left = font.render(clock_text(max(0, NIGHT - night.time)) + " until dawn", True, WHITE)
    screen.blit(left, left.get_rect(center=(WIDTH // 2, 24)))
    if night.state == "lost":
        message = big_font.render("The keep has fallen", True, WHITE)
        screen.blit(message, message.get_rect(center=(WIDTH // 2, 200)))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()