A Locked Door

Part of the Worlds section of Coddy's Pygame journey. Lesson 34 of 35.

A door closes the tunnel near the end of the cave, and a key lies on the floor before it. The door is two D tiles. Add their Rects to walls, so the collision code stops the player, and to tiles with door_img, so they are drawn. Keep them in a list doors too.

The K tile is the key, one Rect named key. Touching it sets has_key = True; from then on the key is drawn in the top bar instead of on the floor.

A player pushed against the door touches it but does not overlap it, so test with a Rect 4 pixels wider on each side:

if has_key and doors and player.inflate(8, 0).colliderect(doors[0]):
    for door in doors:
        walls.remove(door)
    tiles = [(image, rect) for image, rect in tiles if rect not in doors]
    doors = []

The door leaves both lists, so it is neither solid nor drawn. The list comprehension builds a new tiles with every pair whose Rect is not a door.

Challenge

Hard

Load key.png and door.png into key_img and door_img; make doors = [] and has_key = False.
In the map loop: for K, key = rect; for D, append the Rect to walls and doors and (door_img, rect) to tiles.
Each frame, after the blobs: touching key sets has_key = True; with the key, touching a door removes all doors as shown.
Draw the key at its x minus camera_x while has_key is False, and at (130, 8) once it is True.

Try it yourself

import pygame

TILE = 36
WIDTH, HEIGHT = 576, 360
SPEED = 4
GRAVITY = 1
JUMP = -15
MAX_FALL = 12

LEVEL = [
    "................................................................",
    "................................................................",
    "................................................................",
    "................................................................",
    "#..............................................................#",
    "#....................C.........................#####...........#",
    "#......CC...C................CC.....CC.........#####.....CC....#",
    "#....................#.........................D...............#",
    "#.P.........#...E....#...^.......K......E......D.C....^......F.#",
    "#######..####################..##########################..#####",
]

pygame.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Moss Caves")
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()


background = pygame.image.load("assets/backgrounds/forest.png").convert_alpha()
grass_img = load("grass.png")
grass_left_img = load("grass_left.png")
grass_right_img = load("grass_right.png")
dirt_img = load("dirt.png")
player_img = load("player.png")
coin_img = load("coin.png")
spikes_img = load("spikes.png")
heart_img = load("heart.png")
heart_empty_img = load("heart_empty.png")
blob_img = load("blob.png")
blob_walk_img = load("blob_walk.png")


def solid(row, col):
    if row < 0 or row >= len(LEVEL) or col < 0 or col >= len(LEVEL[0]):
        return False
    return LEVEL[row][col] == "#"


class Blob(pygame.sprite.Sprite):
    def __init__(self, midbottom):
        super().__init__()
        self.frames = [blob_img, blob_walk_img]
        self.image = blob_img
        self.rect = pygame.Rect(0, 0, 30, 26)
        self.rect.midbottom = midbottom
        self.direction = 1
        self.timer = 0

    def update(self):
        self.timer += 1
        self.image = self.frames[self.timer // 10 % 2]
        self.rect.x += self.direction
        if self.direction > 0:
            ahead = self.rect.right
        else:
            ahead = self.rect.left - 1
        hit_wall = any(self.rect.colliderect(wall) for wall in walls)
        ground_ahead = any(wall.collidepoint(ahead, self.rect.bottom) for wall in walls)
        if hit_wall or not ground_ahead:
            self.rect.x -= self.direction
            self.direction = -self.direction


walls = []
tiles = []
coins = []
spikes = []
blobs = pygame.sprite.Group()
for row, line in enumerate(LEVEL):
    for col, char in enumerate(line):
        rect = pygame.Rect(col * TILE, row * TILE, TILE, TILE)
        if char == "#":
            if solid(row - 1, col):
                image = dirt_img
            elif not solid(row, col - 1) and solid(row, col + 1):
                image = grass_left_img
            elif solid(row, col - 1) and not solid(row, col + 1):
                image = grass_right_img
            else:
                image = grass_img
            walls.append(rect)
            tiles.append((image, rect))
        elif char == "P":
            start = rect.midbottom
        elif char == "C":
            coins.append(rect)
        elif char == "^":
            spikes.append(pygame.Rect(rect.x, rect.y + 18, TILE, 18))
        elif char == "E":
            blobs.add(Blob(rect.midbottom))

level_width = len(LEVEL[0]) * TILE
player = player_img.get_rect(midbottom=start)
vel_y = 0
on_ground = False
camera_x = 0
coins_collected = 0
lives = 3

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN and event.key in (pygame.K_SPACE, pygame.K_UP):
            if on_ground:
                vel_y = JUMP
        elif event.type == pygame.KEYUP and event.key in (pygame.K_SPACE, pygame.K_UP):
            if vel_y < -4:
                vel_y = -4

    keys = pygame.key.get_pressed()
    dx = 0
    if keys[pygame.K_LEFT]:
        dx -= SPEED
    if keys[pygame.K_RIGHT]:
        dx += SPEED

    player.x += dx
    for wall in walls:
        if player.colliderect(wall):
            if dx > 0:
                player.right = wall.left
            elif dx < 0:
                player.left = wall.right

    vel_y = min(vel_y + GRAVITY, MAX_FALL)
    player.y += vel_y
    on_ground = False
    for wall in walls:
        if player.colliderect(wall):
            if vel_y > 0:
                player.bottom = wall.top
                on_ground = True
            elif vel_y < 0:
                player.top = wall.bottom
            vel_y = 0

    hurt = False
    if player.top > HEIGHT:
        hurt = True

    for coin in coins[:]:
        if player.colliderect(coin):
            coins.remove(coin)
            coins_collected += 1
    for spike in spikes:
        if player.colliderect(spike):
            hurt = True

    blobs.update()
    for blob in blobs:
        if player.colliderect(blob.rect):
            if vel_y > 0 and player.bottom < blob.rect.centery:
                blob.kill()
                vel_y = -8
            else:
                hurt = True

    if hurt:
        lives -= 1
        player.midbottom = start
        vel_y = 0

    camera_x = player.centerx - WIDTH // 2
    camera_x = max(0, min(camera_x, level_width - WIDTH))

    shift = camera_x // 3 % 72
    for y in range(0, HEIGHT, 72):
        for x in range(-shift, WIDTH, 72):
            screen.blit(background, (x, y))
    for image, rect in tiles:
        screen.blit(image, (rect.x - camera_x, rect.y))
    for coin in coins:
        screen.blit(coin_img, (coin.x - camera_x, coin.y))
    for spike in spikes:
        screen.blit(spikes_img, (spike.x - camera_x, spike.y - 18))
    for blob in blobs:
        spot = blob.image.get_rect(midbottom=(blob.rect.centerx - camera_x, blob.rect.bottom))
        screen.blit(blob.image, spot)
    screen.blit(player_img, (player.x - camera_x, player.y))
    for i in range(3):
        if i < lives:
            screen.blit(heart_img, (10 + i * 40, 8))
        else:
            screen.blit(heart_empty_img, (10 + i * 40, 8))
    text = font.render(f"Coins: {coins_collected}", True, (255, 255, 255))
    screen.blit(text, text.get_rect(topright=(WIDTH - 12, 14)))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()