The Boss Calls Bats
Lesson 17 of 20 in Coddy's Pygame Project: Hold the Keep course.
A good boss changes as the fight goes on. Below half its health this one calls for help: every two seconds, three bats appear around it. Fights in stages like this are called phases.
boss = self.boss
if boss and boss.alive() and boss.hp < MONSTERS["boss"]["hp"] // 2:
if self.time % 120 == 0:
for _ in range(3):
offset = (random.randint(-50, 50), random.randint(-50, 50))
self.monsters.add(Monster("bat", boss.pos + offset))boss and boss.alive() reads: there is a boss, and it has not fallen. and stops at the first false part, so boss.alive() is never asked of None.
A Vector2 plus a tuple of two numbers is a Vector2, so boss.pos + offset is a point near the boss.
Challenge
Medium- At the end of
spawn, while the boss is alive with less than half of its 120 health, add three bats every 120 frames, each up to 50 pixels from the boss in x and y.
Try it yourself
import random
import pygame
WIDTH, HEIGHT = 720, 480
TILE = 48
NIGHT = 60 * 60 * 4
BOSS_AT = NIGHT - 60 * 60
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, "size": 28},
"bat": {"image": load("dungeon_bat.png"), "speed": 1.6, "hp": 1, "size": 28},
"spider": {"image": load("spider.png"), "speed": 1.2, "hp": 3, "size": 28},
"ghost": {"image": load("ghost.png"), "speed": 0.8, "hp": 4, "size": 28},
"boss": {"image": pygame.transform.scale(load("ghost.png"), (96, 96)), "speed": 0.7, "hp": 120, "size": 64},
}
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, MONSTERS[kind]["size"], MONSTERS[kind]["size"])
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.boss = None
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()))
if self.boss is None and self.time >= BOSS_AT:
self.boss = Monster("boss", (WIDTH // 2, -40))
self.monsters.add(self.boss)
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()
drops = 8 if monster.kind == "boss" else 1
for _ in range(drops):
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()
All lessons in Pygame Project: Hold the Keep
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