2nd/10_Wiki/Topics/Backend/Unity.md

---
id: wiki-2026-0508-unity
title: Unity
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Unity Engine, Unity3D, Unity 6]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [game-engine, c-sharp, realtime, multiplayer, dots]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: C#
  framework: Unity 6 (DOTS, Netcode for GameObjects)
---

# Unity

## 매 한 줄
> **"매 cross-platform realtime engine 의 component 기반 scene graph + 매 C# scripting 의 ECS hybrid"**. 2005 OS X-only IDE 로 출발, 2026 Unity 6 의 DOTS (Data-Oriented Tech Stack) + URP/HDRP + Netcode 가 indie ~ AAA 까지 cover. 매 backend 관점: dedicated game server, matchmaking, persistence layer 가 hot path.

## 매 핵심

### 매 GameObject + Component
- `GameObject` = container, `MonoBehaviour` 매 lifecycle hook (`Awake → Start → Update → FixedUpdate → LateUpdate`).
- 매 inheritance 보다 composition 우선 — 매 `RequireComponent` 의 사용.

### 매 ECS / DOTS
- `Entity` (ID) + `IComponentData` (struct) + `SystemBase` (logic). 매 Burst compiler + Job system 의 SIMD/multi-thread.
- 100k+ entities @ 60fps 가 mobile 에서도 가능.

### 매 Networking
- Netcode for GameObjects (NGO) — 매 NetworkBehaviour, NetworkVariable, ClientRpc/ServerRpc.
- DGS (Dedicated Game Server) on Unity Multiplay (Unity Cloud) 또는 self-host (k8s).

### 매 응용
1. 매 mobile/PC/console game (Genshin-style live ops 포함).
2. 매 AR/VR (XR Interaction Toolkit, visionOS).
3. 매 digital twin / BIM 시각화 (non-game enterprise).

## 💻 패턴

### MonoBehaviour 기본
```csharp
using UnityEngine;

public class PlayerController : MonoBehaviour
{
    [SerializeField] float speed = 5f;
    Rigidbody rb;

    void Awake() => rb = GetComponent<Rigidbody>();

    void FixedUpdate()
    {
        var input = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
        rb.MovePosition(rb.position + input * speed * Time.fixedDeltaTime);
    }
}
```

### DOTS / ECS System
```csharp
using Unity.Burst;
using Unity.Entities;
using Unity.Mathematics;
using Unity.Transforms;

[BurstCompile]
public partial struct MoveSystem : ISystem
{
    public void OnUpdate(ref SystemState state)
    {
        float dt = SystemAPI.Time.DeltaTime;
        foreach (var (transform, vel) in SystemAPI.Query<RefRW<LocalTransform>, RefRO<Velocity>>())
            transform.ValueRW.Position += vel.ValueRO.Value * dt;
    }
}
```

### Netcode RPC
```csharp
public class PlayerNet : NetworkBehaviour
{
    [ServerRpc] public void FireServerRpc(Vector3 dir) {
        // server-authoritative damage
        SpawnProjectileClientRpc(dir);
    }
    [ClientRpc] void SpawnProjectileClientRpc(Vector3 dir) { /* visual only */ }
}
```

### Addressables (async asset load)
```csharp
var handle = Addressables.LoadAssetAsync<GameObject>("Boss/FinalBoss");
var prefab = await handle.Task;
Instantiate(prefab, spawnPoint.position, Quaternion.identity);
```

### ScriptableObject (data-driven)
```csharp
[CreateAssetMenu(menuName="Game/WeaponDef")]
public class WeaponDef : ScriptableObject {
    public int damage; public float fireRate; public AudioClip sfx;
}
```

### UniTask (struct-based async)
```csharp
async UniTaskVoid LoadScene() {
    await SceneManager.LoadSceneAsync("Boss").ToUniTask();
    await UniTask.Delay(500);
    BossUI.Show();
}
```

### Dedicated Server build
```bash
# Linux server build via CLI
Unity -batchmode -nographics -quit \
  -buildTarget LinuxServer \
  -executeMethod Builder.BuildServer \
  -projectPath . -logFile build.log
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| Indie 2D/3D, fast iteration | MonoBehaviour + URP |
| 10k+ units (RTS, swarm) | DOTS + Burst |
| Authoritative multiplayer | Netcode + DGS on Multiplay |
| Cross-platform UI tool | UI Toolkit (UXML/USS) |
| 매 cinematic | Timeline + Cinemachine |

**기본값**: MonoBehaviour + URP + Addressables. Scale 한계 도달 시 hot path 만 DOTS 로 migrate.

## 🔗 Graph

## 🤖 LLM 활용
**언제**: boilerplate MonoBehaviour, shader scaffolding, editor tool script, ECS conversion outline.
**언제 X**: 매 performance-critical hot loop (LLM 의 GC alloc 무지) / 매 latest API breaking changes (Unity 6 → 7 transition).

## ❌ 안티패턴
- **Update() everywhere**: 매 frame 의 `GetComponent` / `Find` 호출. Cache in Awake.
- **String-based GameObject.Find**: 매 fragile + slow. Use serialized refs.
- **Coroutine for heavy work**: 매 main thread block. Use Job system or async.
- **Resources/ folder abuse**: 매 build size bloat. Use Addressables.
- **No object pooling**: 매 bullet/particle spam → GC spike. Pool everything reusable.

## 🧪 검증 / 중복
- Verified (Unity 6 docs, Unite 2025 sessions).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — Unity 6 + DOTS + Netcode 패턴 정리 |