Collect the Coins

Part of the Worlds section of Coddy's Pygame journey. Lesson 31 of 35.

Coins give the explorer something to go after: a few hang over the pits, where reaching them is a risk.

Read every C into a list of Rects, the whole tile, since coin.png has its own empty border. When the player touches a coin, take it out of the list and count it:

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

coins[:] is a copy of the list. Removing items from a list while a loop walks over it shifts the items under the loop and skips one; walking over a copy avoids that.

Show the count in the top right corner. It belongs to the window, not the level, so it is drawn without the camera:

font = pygame.font.Font("assets/fonts/pixel.ttf", 24)
# in the loop
text = font.render(f"Coins: {coins_collected}", True, (255, 255, 255))
screen.blit(text, text.get_rect(topright=(WIDTH - 12, 14)))

Challenge

Medium

Load coin.png into coin_img and make font from assets/fonts/pixel.ttf at size 24.
Make coins = [] and coins_collected = 0; in the map loop, append the tile Rect for each C.
Each frame, after the movement, remove each coin the player touches and add 1 to coins_collected.
Draw each coin at its x minus camera_x, and the text Coins: and the count at the top right, as shown.

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()


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")


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] == "#"


walls = []
tiles = []
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

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

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

    if player.top > HEIGHT:
        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))
    screen.blit(player_img, (player.x - camera_x, player.y))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()