The Boss

Lesson 16 of 20 in Coddy's Pygame Project: Hold the Keep course.

One minute before dawn the boss comes: a ghost twice the size, slow but with 120 health. pygame.transform.scale(image, (96, 96)) gives a bigger copy of a picture, so the boss needs no picture of its own.

The boss is bigger, so its Rect is too. Give every kind a "size" in MONSTERS, 28 for the others and 64 for the boss, and use it for the Rect.

Only one boss should come. self.boss starts as None and holds the boss once it is made, which both stops a second one and lets the next lesson find it:

if self.boss is None and self.time >= BOSS_AT:
    self.boss = Monster("boss", (WIDTH // 2, -40))
    self.monsters.add(self.boss)

The boss is a Monster in self.monsters, so it walks, gets hit, flashes and falls with no new code. A fallen boss drops 8 gems.

Challenge

Medium

Add BOSS_AT = NIGHT - 60 * 60.
Add "size" to every kind: 28, and the "boss" row: picture pygame.transform.scale(load("ghost.png"), (96, 96)), speed 0.7, hp 120, size 64. Monsters use MONSTERS[kind]["size"] for their Rect.
self.boss = None in Night, and the code above at the end of spawn.
When a monster falls, drop 8 gems for the boss and 1 for any other.

Try it yourself

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"],
]
UPGRADES = {
    "Quick bolts": "Bolts fire more often",
    "Sharp bolts": "Bolts hit harder",
    "Spinning axe": "One more axe circles you",
    "Swift boots": "You walk faster",
    "Gem magnet": "Gems come from further",
    "Hearty meal": "Get back a heart",
}
WHITE = (240, 240, 240)
BOLT = (120, 200, 255)
GOLD = (250, 200, 60)

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)
small_font = pygame.font.Font("assets/fonts/pixel.ttf", 16)
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")
gem_img = load("gem.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")
gem_sound = sound("coin.ogg")
level_sound = sound("powerup.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))
cover = pygame.Surface((WIDTH, HEIGHT), pygame.SRCALPHA)
cover.fill((0, 0, 0, 150))


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
        self.magnet = 80

    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 Gem(pygame.sprite.Sprite):
    def __init__(self, pos):
        super().__init__()
        self.rect = pygame.Rect(0, 0, 24, 24)
        self.rect.center = pos
        self.rect.clamp_ip(courtyard)
        self.pos = pygame.Vector2(self.rect.center)

    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


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.gems = pygame.sprite.Group()
        self.xp = 0
        self.level = 1
        self.need = 5
        self.choices = []
        self.pick = 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()
                self.gems.add(Gem(monster.pos))

    def collect(self):
        for gem in pygame.sprite.spritecollide(self.knight, self.gems, True):
            self.xp += 1
            gem_sound.play()
        if self.xp >= self.need:
            self.xp -= self.need
            self.level += 1
            self.need += 4
            self.choices = random.sample(list(UPGRADES), 3)
            self.pick = 1
            self.state = "levelup"
            level_sound.play()

    def upgrade(self, name):
        knight = self.knight
        if name == "Quick bolts":
            knight.bolt_wait = max(8, knight.bolt_wait - 8)
        elif name == "Sharp bolts":
            knight.bolt_damage += 1
        elif name == "Spinning axe":
            knight.axes += 1
        elif name == "Swift boots":
            knight.speed += 1
        elif name == "Gem magnet":
            knight.magnet += 40
        elif name == "Hearty meal":
            knight.hearts = min(knight.max_hearts, knight.hearts + 1)
        self.state = "playing"

    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.gems.update(self.knight)
        self.shoot()
        self.hurt_monsters()
        self.collect()
        self.take_hits()


night = Night()

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN:
            if night.state == "levelup":
                if event.key == pygame.K_LEFT:
                    night.pick = (night.pick - 1) % 3
                elif event.key == pygame.K_RIGHT:
                    night.pick = (night.pick + 1) % 3
                elif event.key == pygame.K_SPACE:
                    night.upgrade(night.choices[night.pick])

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

    screen.blit(background, (0, 0))
    knight = night.knight
    for gem in night.gems:
        draw(gem_img, gem.rect.center)
    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)))
    label = font.render(f"Level {night.level}", True, WHITE)
    screen.blit(label, label.get_rect(topright=(WIDTH - 10, 4)))
    pygame.draw.rect(screen, (40, 40, 60), (WIDTH - 160, 30, 150, 10))
    pygame.draw.rect(screen, GOLD, (WIDTH - 160, 30, 150 * night.xp // night.need, 10))
    if night.state == "levelup":
        screen.blit(cover, (0, 0))
        title = big_font.render("Level up! Pick one", True, GOLD)
        screen.blit(title, title.get_rect(center=(WIDTH // 2, 130)))
        for i, name in enumerate(night.choices):
            card = pygame.Rect(60 + i * 210, 190, 180, 120)
            pygame.draw.rect(screen, (40, 40, 60), card)
            if i == night.pick:
                pygame.draw.rect(screen, GOLD, card, 4)
            else:
                pygame.draw.rect(screen, WHITE, card, 2)
            text = font.render(name, True, WHITE)
            screen.blit(text, text.get_rect(center=(card.centerx, card.y + 40)))
            about = small_font.render(UPGRADES[name], True, WHITE)
            screen.blit(about, about.get_rect(center=(card.centerx, card.y + 80)))
        hint = font.render("Left and Right to choose, Space to take it", True, WHITE)
        screen.blit(hint, hint.get_rect(center=(WIDTH // 2, 360)))
    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()