alien_invasion.py

import pygame
from pygame.sprite import Group

from settings import Config
from game_stats import GameState
from scoreboard import HUD
from button import Button
from ship import Ship
import game_functions as gf


def main():
    pygame.init()

    cfg = Config()
    screen = pygame.display.set_mode((cfg.screen_w, cfg.screen_h))
    pygame.display.set_caption("Alien Invasion")

    start_button = Button(cfg, screen, "Play")

    state = GameState(cfg)
    hud = HUD(cfg, screen, state)

    ship = Ship(cfg, screen)
    shots = Group()
    swarm = Group()

    gf.build_fleet(cfg, screen, ship, swarm)

    while True:
        gf.process_input(cfg, screen, state, hud, start_button, ship, swarm, shots)

        if state.active:
            ship.update()
            gf.step_shots(cfg, screen, state, hud, ship, swarm, shots)
            gf.step_swarm(cfg, screen, state, hud, ship, swarm, shots)

        gf.draw_frame(cfg, screen, state, hud, ship, swarm, shots, start_button)


if __name__ == "__main__":
    main()

game_functions.py

import sys
from time import sleep

import pygame

from bullet import Laser
from alien import Invader


def handle_keydown(evt, cfg, screen, ship, shots):
    if evt.key == pygame.K_RIGHT:
        ship.heading_right = True
    elif evt.key == pygame.K_LEFT:
        ship.heading_left = True
    elif evt.key == pygame.K_SPACE:
        spawn_laser(cfg, screen, ship, shots)
    elif evt.key == pygame.K_q:
        sys.exit()


def handle_keyup(evt, ship):
    if evt.key == pygame.K_RIGHT:
        ship.heading_right = False
    elif evt.key == pygame.K_LEFT:
        ship.heading_left = False


def process_input(cfg, screen, state, hud, start_button, ship, swarm, shots):
    for evt in pygame.event.get():
        if evt.type == pygame.QUIT:
            sys.exit()
        elif evt.type == pygame.KEYDOWN:
            handle_keydown(evt, cfg, screen, ship, shots)
        elif evt.type == pygame.KEYUP:
            handle_keyup(evt, ship)
        elif evt.type == pygame.MOUSEBUTTONDOWN:
            mx, my = pygame.mouse.get_pos()
            start_game_if_clicked(cfg, screen, state, hud, start_button, ship, swarm, shots, mx, my)


def start_game_if_clicked(cfg, screen, state, hud, start_button, ship, swarm, shots, mx, my):
    clicked = start_button.rect.collidepoint(mx, my)
    if clicked and not state.active:
        cfg.init_dynamic()
        pygame.mouse.set_visible(False)

        state.reset()
        state.active = True

        hud.update_score_surface()
        hud.update_high_score_surface()
        hud.update_level_surface()
        hud.update_lives_group()

        swarm.empty()
        shots.empty()

        build_fleet(cfg, screen, ship, swarm)
        ship.recenter()


def draw_frame(cfg, screen, state, hud, ship, swarm, shots, start_button):
    screen.fill(cfg.background_color)

    for s in shots.sprites():
        s.draw()

    ship.blitme()
    swarm.draw(screen)

    hud.draw()

    if not state.active:
        start_button.draw_button()

    pygame.display.flip()


def step_shots(cfg, screen, state, hud, ship, swarm, shots):
    shots.update()

    for s in shots.copy():
        if s.rect.bottom <= 0:
            shots.remove(s)

    resolve_impacts(cfg, screen, state, hud, ship, swarm, shots)


def resolve_impacts(cfg, screen, state, hud, ship, swarm, shots):
    impacts = pygame.sprite.groupcollide(shots, swarm, True, True)

    if impacts:
        destroyed = sum(len(v) for v in impacts.values())
        state.score += cfg.invader_points * destroyed
        hud.update_score_surface()
        update_high_score(state, hud)

    if len(swarm) == 0:
        shots.empty()
        cfg.accelerate()
        state.level += 1
        hud.update_level_surface()
        build_fleet(cfg, screen, ship, swarm)


def spawn_laser(cfg, screen, ship, shots):
    if len(shots) < cfg.shot_limit:
        shots.add(Laser(cfg, screen, ship))


def columns_for_row(cfg, invader_w):
    free_x = cfg.screen_w - 2 * invader_w
    return int(free_x // (2 * invader_w))


def rows_for_screen(cfg, ship_h, invader_h):
    free_y = cfg.screen_h - (3 * invader_h) - ship_h
    return int(free_y // (2 * invader_h))


def add_invader(cfg, screen, swarm, col_idx, row_idx):
    inv = Invader(cfg, screen)
    w = inv.rect.width
    inv.x = w + 2 * w * col_idx
    inv.rect.x = inv.x
    inv.rect.y = inv.rect.height + 2 * inv.rect.height * row_idx
    swarm.add(inv)


def build_fleet(cfg, screen, ship, swarm):
    sample = Invader(cfg, screen)
    cols = columns_for_row(cfg, sample.rect.width)
    rows = rows_for_screen(cfg, ship.rect.height, sample.rect.height)

    for r in range(rows):
        for c in range(cols):
            add_invader(cfg, screen, swarm, c, r)


def on_edge(cfg, swarm):
    for inv in swarm.sprites():
        if inv.check_edges():
            shift_and_flip(cfg, swarm)
            break


def shift_and_flip(cfg, swarm):
    for inv in swarm.sprites():
        inv.rect.y += cfg.fleet_drop
    cfg.fleet_dir *= -1


def ship_hit(cfg, screen, state, hud, ship, swarm, shots):
    if state.lives > 0:
        state.lives -= 1
        hud.update_lives_group()

        swarm.empty()
        shots.empty()

        build_fleet(cfg, screen, ship, swarm)
        ship.recenter()

        sleep(0.5)
    else:
        state.active = False
        pygame.mouse.set_visible(True)


def step_swarm(cfg, screen, state, hud, ship, swarm, shots):
    on_edge(cfg, swarm)
    swarm.update()

    if pygame.sprite.spritecollideany(ship, swarm):
        ship_hit(cfg, screen, state, hud, ship, swarm, shots)

    check_bottom(cfg, screen, state, hud, ship, swarm, shots)


def check_bottom(cfg, screen, state, hud, ship, swarm, shots):
    screen_rect = screen.get_rect()
    for inv in swarm.sprites():
        if inv.rect.bottom >= screen_rect.bottom:
            ship_hit(cfg, screen, state, hud, ship, swarm, shots)
            break


def update_high_score(state, hud):
    if state.score > state.high_score:
        state.high_score = state.score
        hud.update_high_score_surface()

alien.py

import pygame
from pygame.sprite import Sprite


class Invader(Sprite):
    def __init__(self, cfg, screen):
        super().__init__()
        self.screen = screen
        self.cfg = cfg

        self.image = pygame.image.load("images/alien.bmp")
        self.rect = self.image.get_rect()

        self.rect.x = self.rect.width
        self.rect.y = self.rect.height

        self.x = float(self.rect.x)

    def blitme(self):
        self.screen.blit(self.image, self.rect)

    def check_edges(self):
        bounds = self.screen.get_rect()
        return self.rect.right >= bounds.right or self.rect.left <= 0

    def update(self):
        self.x += self.cfg.invader_speed * self.cfg.fleet_dir
        self.rect.x = self.x

bulllet.py

import pygame
from pygame.sprite import Sprite


class Laser(Sprite):
    def __init__(self, cfg, screen, ship):
        super().__init__()
        self.screen = screen

        self.rect = pygame.Rect(0, 0, cfg.shot_w, cfg.shot_h)
        self.rect.centerx = ship.rect.centerx
        self.rect.top = ship.rect.top

        self.y = float(self.rect.y)
        self.color = cfg.shot_color
        self.speed = cfg.shot_speed

    def update(self):
        self.y -= self.speed
        self.rect.y = self.y

    def draw(self):
        pygame.draw.rect(self.screen, self.color, self.rect)

buttton.py

import pygame
import pygame.font


class Button:
    def __init__(self, cfg, screen, msg):
        self.screen = screen
        self.screen_rect = screen.get_rect()

        self.width, self.height = 200, 50
        self.bg_color = (1, 220, 212)
        self.text_color = (255, 255, 255)
        self.font = pygame.font.SysFont(None, 48)

        self.rect = pygame.Rect(0, 0, self.width, self.height)
        self.rect.center = self.screen_rect.center

        self._render_text(msg)

    def _render_text(self, msg):
        self.msg_image = self.font.render(msg, True, self.text_color, self.bg_color)
        self.msg_rect = self.msg_image.get_rect()
        self.msg_rect.center = self.rect.center

    def draw_button(self):
        self.screen.fill(self.bg_color, self.rect)
        self.screen.blit(self.msg_image, self.msg_rect)

game_stats.py

class GameState:
    def __init__(self, cfg):
        self.cfg = cfg
        self.active = False
        self.high_score = 0
        self.reset()

    def reset(self):
        self.lives = self.cfg.ship_lives
        self.score = 0
        self.level = 1

scoreboard.py

import pygame.font
from pygame.sprite import Group

from ship import Ship


class HUD:
    def __init__(self, cfg, screen, state):
        self.cfg = cfg
        self.screen = screen
        self.screen_rect = screen.get_rect()
        self.state = state

        self.text_color = (30, 30, 30)
        self.font = pygame.font.SysFont(None, 48)

        self.update_score_surface()
        self.update_high_score_surface()
        self.update_level_surface()
        self.update_lives_group()

    def update_score_surface(self):
        s = f"{self.state.score:,}"
        self.score_img = self.font.render(s, True, self.text_color, self.cfg.background_color)
        self.score_rect = self.score_img.get_rect()
        self.score_rect.right = self.screen_rect.right - 20
        self.score_rect.top = 20

    def update_high_score_surface(self):
        s = f"{self.state.high_score:,}"
        self.high_img = self.font.render(s, True, self.text_color, self.cfg.background_color)
        self.high_rect = self.high_img.get_rect()
        self.high_rect.centerx = self.screen_rect.centerx
        self.high_rect.top = self.score_rect.top

    def update_level_surface(self):
        s = str(self.state.level)
        self.level_img = self.font.render(s, True, self.text_color, self.cfg.background_color)
        self.level_rect = self.level_img.get_rect()
        self.level_rect.right = self.score_rect.right
        self.level_rect.top = self.score_rect.bottom + 10

    def update_lives_group(self):
        self.lives_group = Group()
        for i in range(self.state.lives):
            ship = Ship(self.cfg, self.screen)
            ship.rect.x = 10 + i * ship.rect.width
            ship.rect.y = 10
            self.lives_group.add(ship)

    def draw(self):
        self.screen.blit(self.score_img, self.score_rect)
        self.screen.blit(self.high_img, self.high_rect)
        self.screen.blit(self.level_img, self.level_rect)
        self.lives_group.draw(self.screen)

settings.py

class Config:
    def __init__(self):
        # Display
        self.screen_w = 1200
        self.screen_h = 800
        self.background_color = (164, 177, 161)

        # Ship
        self.ship_lives = 3

        # Shots
        self.shot_w = 3
        self.shot_h = 15
        self.shot_color = (60, 60, 60)
        self.shot_limit = 3

        # Fleet
        self.fleet_drop = 10

        # Scaling
        self.speed_scale = 1.1
        self.points_scale = 1.5

        self.init_dynamic()

    def init_dynamic(self):
        self.ship_speed = 1.5
        self.shot_speed = 7.0
        self.invader_speed = 0.6
        self.fleet_dir = 1  # 1: right, -1: left
        self.invader_points = 50

    def accelerate(self):
        self.ship_speed *= self.speed_scale
        self.shot_speed *= self.speed_scale
        self.invader_speed *= self.speed_scale
        self.invader_points = int(self.invader_points * self.points_scale)

ship.py

import pygame
from pygame.sprite import Sprite


class Ship(Sprite):
    def __init__(self, cfg, screen):
        super().__init__()
        self.screen = screen
        self.cfg = cfg

        self.image = pygame.image.load("images/ship.bmp")
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom

        self.center_x = float(self.rect.centerx)

        self.heading_right = False
        self.heading_left = False

    def update(self):
        if self.heading_right and self.rect.right < self.screen_rect.right:
            self.center_x += self.cfg.ship_speed
        if self.heading_left and self.rect.left > 0:
            self.center_x -= self.cfg.ship_speed
        self.rect.centerx = self.center_x

    def blitme(self):
        self.screen.blit(self.image, self.rect)

    def recenter(self):
        self.center_x = self.screen_rect.centerx