Game Engines

Unity Architecture

UNITY COMPONENT SYSTEM:
┌─────────────────────────────────────────────────────────────┐
│  GameObject                                                  │
│  ├─ Transform (required)                                    │
│  ├─ Renderer (MeshRenderer, SpriteRenderer)                │
│  ├─ Collider (BoxCollider, CapsuleCollider)                │
│  ├─ Rigidbody (physics simulation)                         │
│  └─ Custom MonoBehaviour scripts                           │
│                                                              │
│  LIFECYCLE:                                                  │
│  Awake() → OnEnable() → Start() → FixedUpdate() →          │
│  Update() → LateUpdate() → OnDisable() → OnDestroy()       │
└─────────────────────────────────────────────────────────────┘

// ✅ Production-Ready: Unity Component Pattern
public class PlayerController : MonoBehaviour
{
    [Header("Movement Settings")]
    [SerializeField] private float moveSpeed = 5f;
    [SerializeField] private float jumpForce = 10f;

    [Header("Ground Check")]
    [SerializeField] private Transform groundCheck;
    [SerializeField] private float groundRadius = 0.2f;
    [SerializeField] private LayerMask groundLayer;

    private Rigidbody2D _rb;
    private bool _isGrounded;
    private float _horizontalInput;

    // Cache components in Awake
    private void Awake()
    {
        _rb = GetComponent<Rigidbody2D>();
    }

    private void Update()
    {
        // Input in Update (frame-rate independent)
        _horizontalInput = Input.GetAxisRaw("Horizontal");

        if (Input.GetButtonDown("Jump") && _isGrounded)
        {
            Jump();
        }
    }

    private void FixedUpdate()
    {
        // Physics in FixedUpdate (consistent timing)
        CheckGround();
        Move();
    }

    private void CheckGround()
    {
        _isGrounded = Physics2D.OverlapCircle(
            groundCheck.position, groundRadius, groundLayer);
    }

    private void Move()
    {
        _rb.velocity = new Vector2(
            _horizontalInput * moveSpeed,
            _rb.velocity.y);
    }

    private void Jump()
    {
        _rb.velocity = new Vector2(_rb.velocity.x, jumpForce);
    }
}

Unreal Engine Architecture

UNREAL ACTOR SYSTEM:
┌─────────────────────────────────────────────────────────────┐
│  AActor (Base class for all game objects)                   │
│  ├─ APawn (Can be possessed by controller)                 │
│  │   └─ ACharacter (Has CharacterMovementComponent)        │
│  ├─ AGameMode (Game rules)                                 │
│  └─ APlayerController (Player input handling)              │
│                                                              │
│  COMPONENTS:                                                 │
│  ├─ USceneComponent (Transform hierarchy)                  │
│  ├─ UStaticMeshComponent (3D model)                        │
│  ├─ UCapsuleComponent (Collision)                          │
│  └─ UCharacterMovementComponent (Movement logic)           │
│                                                              │
│  LIFECYCLE:                                                  │
│  Constructor → BeginPlay() → Tick() → EndPlay()            │
└─────────────────────────────────────────────────────────────┘

// ✅ Production-Ready: Unreal Character
UCLASS()
class MYGAME_API AMyCharacter : public ACharacter
{
    GENERATED_BODY()