Hearts

Lesson 7 of 20 in Coddy's Pygame Project: Hold the Keep course.

A monster that reaches the knight costs a heart. Without a pause after a hit, a monster standing on the knight would take a heart every frame, all five in a twelfth of a second. So a hit starts a counter, hurt, and while it counts down nothing can hurt the knight:

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

spritecollideany(sprite, group) gives the first sprite in the group whose rect overlaps, or None.

The game now has states: "playing" and "lost". The loop runs night.update only while playing, so when the hearts run out everything stops where it is.

While hurt counts, draw the knight only when knight.hurt % 10 < 5: it blinks, and the player sees why nothing hurts.

Challenge

Medium

Give the knight hearts = 5, max_hearts = 5 and hurt = 0; give Night state = "playing".
Write take_hits as above; when the hearts reach 0, set self.state = "lost". Call it last in update.
In the loop, update only if night.state == "playing", and draw the knight only when knight.hurt % 10 < 5.
Load heart.png and heart_empty.png as heart_img and empty_img. For each of the max_hearts, blit a full or an empty heart at (8 + i * 34, 6).
Make big_font = pygame.font.Font("assets/fonts/pixel.ttf", 48) and, when lost, draw "The keep has fallen" centred at (360, 200).

Try it yourself

import random
import pygame

WIDTH, HEIGHT = 720, 480
TILE = 48
NIGHT = 60 * 60 * 4
WHITE = (240, 240, 240)

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)


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")
MONSTERS = {
    "slime": {"image": load("slime.png"), "speed": 1.0},
}

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

    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.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


class Night:
    def __init__(self):
        self.knight = Knight()
        self.time = 0
        self.monsters = pygame.sprite.Group()

    def spawn(self):
        if self.time % 60 == 0:
            self.monsters.add(Monster("slime", edge_point()))

    def update(self, keys):
        self.time += 1
        self.knight.move(keys)
        self.spawn()
        self.monsters.update(self.knight.rect.center)


night = Night()

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

    night.update(pygame.key.get_pressed())

    screen.blit(background, (0, 0))
    knight = night.knight
    for monster in night.monsters:
        draw(monster.image, monster.rect.center)
    draw(knight.image, knight.rect.center)
    left = font.render(clock_text(max(0, NIGHT - night.time)) + " until dawn", True, WHITE)
    screen.blit(left, left.get_rect(center=(WIDTH // 2, 24)))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()