Skip to content

🧠 Core Concepts

Game Architecture

Alien Invasion follows a component-based architecture with the following key concepts:

Entity Component System (ECS)

  1. Entities

    • Game objects (ship, aliens, bullets)
    • Unique identifiers
    • Component containers

  2. Components

    • Position
    • Velocity
    • Sprite
    • Collision
    • Health

  3. Systems

    • Movement
    • Rendering
    • Collision detection
    • Input handling

State Management

The game uses a state machine to manage different game screens:

class GameState(Enum):
    MENU = 1
    PLAYING = 2
    PAUSED = 3
    GAME_OVER = 4

Key Systems

1. Input System

Handles player input and controls:

class InputSystem:
    def handle_events(self):
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                return False
            # Handle other events
        return True

2. Physics System

Manages movement and collisions:

class PhysicsSystem:
    def update(self, entities):
        for entity in entities:
            position = entity.get_component(Position)
            velocity = entity.get_component(Velocity)
            position.x += velocity.x
            position.y += velocity.y

3. Rendering System

Handles drawing game objects:

class RenderSystem:
    def render(self, screen, entities):
        for entity in entities:
            sprite = entity.get_component(Sprite)
            position = entity.get_component(Position)
            screen.blit(sprite.image, (position.x, position.y))

Design Patterns

1. Observer Pattern

Used for event handling:

class EventManager:
    def __init__(self):
        self.listeners = {}

    def subscribe(self, event_type, listener):
        if event_type not in self.listeners:
            self.listeners[event_type] = []
        self.listeners[event_type].append(listener)

2. Factory Pattern

Used for entity creation:

class EntityFactory:
    def create_ship(self, x, y):
        ship = Entity()
        ship.add_component(Position(x, y))
        ship.add_component(Sprite("ship.png"))
        return ship

3. Strategy Pattern

Used for different behaviors:

class AlienBehavior:
    def update(self, alien):
        pass

class BasicAlienBehavior(AlienBehavior):
    def update(self, alien):
        # Basic movement pattern
        pass

Code Organization

Directory Structure

src/
├── config/        # Configuration files
├── core/          # Core systems
├── entities/      # Game entities
├── systems/       # Game systems
└── utils/         # Utility functions

File Naming

  • Use snake_case for file names
  • Prefix system files with system name
  • Suffix component files with _component

Best Practices

1. Code Style

  • Follow PEP 8 guidelines
  • Use type hints
  • Document all public APIs

2. Performance

  • Use sprite groups efficiently
  • Minimize surface creation
  • Optimize collision detection

3. Testing

  • Write unit tests
  • Use test fixtures
  • Mock external dependencies

Development Tools

1. Code Quality

  • Black for formatting
  • Flake8 for linting
  • MyPy for type checking

2. Testing

  • pytest for testing
  • Coverage for test coverage
  • Hypothesis for property testing

3. Documentation

  • MkDocs for documentation
  • Docstrings for code documentation
  • Type hints for better IDE support

Next Steps