Core & Architecture

Prefab

A Prefab is a reusable Unity template asset — design once, spawn many times. Change the Prefab and every instance that still inherits those properties updates.

Imagine...

A Prefab is like a bread mold. You design the mold (the Prefab asset) once with all the ingredients. Then you pour dough into it (Instantiate()) and get hundreds of identical loaves in seconds. Need a new flavor? Edit the mold — every future batch picks up the change.

The concept in detail

A Prefab is a .prefab file that stores an entire GameObject hierarchy — Components, settings, and children. Drag it into a Scene and Unity creates a Prefab Instance linked back to that asset.

Prefab Overrides: each Instance can override selected properties (color, HP…) while still inheriting everything else. When the Prefab asset updates, instances without an override pick up the new values automatically.

Nested Prefabs: a Prefab can contain other Prefabs. Handy for a Level Prefab that holds Room Prefabs, each Room holding Enemy Prefabs.

Calling Instantiate()/Destroy() in a tight loop causes lag (Garbage Collection spikes). For high-frequency spawns (machine-gun bullets, VFX…) use Object Pooling.

Diagram: Prefab → Instances

📦 Prefab Asset

Enemy_Goblin.prefab

⚙ Rigidbody · ⚙ Collider · ⚙ EnemyAI

HP: 100 · Speed: 3

↓ Instantiate()

Instance #1

pos: (2, 0, 5)

HP: 100 (from Prefab)

Instance #2 — Override

pos: (-3, 0, 7)

HP: 150 ← Override!

Instance #3

pos: (0, 0, 10)

HP: 100 (from Prefab)

Hands-on steps

Create a Prefab from the Scene

Finish the setup → drag from Hierarchy into an Assets folder in the Project window.

Edit in Prefab Mode

Double-click the .prefab file → isolated edit space. Changes propagate to all Instances.

Assign via [SerializeField]

In the Inspector, drag the Prefab asset from Project onto a field so your script can Instantiate it.

Apply Overrides to the Prefab asset

Select an Instance → Inspector → Overrides → Apply All.

Interactive simulator

Pick a Prefab type, press Instantiate to spawn a copy. Click an Instance to select it and change an Override. Press Destroy to remove it.

Instances: 0

Press "Instantiate()" to spawn a GameObject from the Prefab

Inspector

Select an Instance

Prefab: Enemy_Goblin|Selected: None|Tip: Click an instance to view Properties

Code example

Basic

using UnityEngine;

public class PrefabSpawner : MonoBehaviour
{
  [SerializeField] private GameObject enemyPrefab;
  [SerializeField] private Transform  spawnPoint;

  void Start()
  {
      // Spawn a copy at the spawnPoint pose
      GameObject clone = Instantiate(
          enemyPrefab, spawnPoint.position, spawnPoint.rotation
      );

      // Configure the clone immediately
      EnemyAI ai = clone.GetComponent<EnemyAI>();
      if (ai != null)
      {
          ai.patrolSpeed    = 3f;
          ai.detectionRange = 8f;
      }

      clone.name = $"Enemy_{Random.Range(100, 999)}";
  }
}

Code example

Advanced

using System.Collections;
using UnityEngine;

public class WaveSpawner : MonoBehaviour
{
  [SerializeField] private GameObject[] enemyPrefabs;  // multiple enemy types
  [SerializeField] private Transform[] spawnPoints;   // multiple spawn points
  [SerializeField] private int    enemiesPerWave = 5;
  [SerializeField] private float  spawnInterval  = 0.5f;
  [SerializeField] private float  waveCooldown   = 5f;

  private int _waveCount = 0;

  void Start() => StartCoroutine(SpawnLoop());

  private IEnumerator SpawnLoop()
  {
      while (true)
      {
          _waveCount++;
          for (int i = 0; i < enemiesPerWave; i++)
          {
              // Pick a Prefab and SpawnPoint at random
              var prefab = enemyPrefabs[Random.Range(0, enemyPrefabs.Length)];
              var point  = spawnPoints[Random.Range(0, spawnPoints.Length)];
              Instantiate(prefab, point.position, point.rotation);
              yield return new WaitForSeconds(spawnInterval);
          }
          yield return new WaitForSeconds(waveCooldown);
      }
  }
}

📌 Quick recap

▸Prefab = reusable template — design once, use forever
▸An Instance can Override individual properties
▸Edit the Prefab asset → every linked Instance updates
▸High-frequency spawn → use Object Pooling instead of Instantiate/Destroy

⚠️ Common mistakes

❌ Instantiate without keeping the reference
You spawn it but cannot control that clone later
✅ var clone = Instantiate(prefab);
❌ Instantiate/Destroy every frame in a hot loop
GC spikes and hitching — especially machine-gun bullets
✅ Object Pool: pre-create, enable/disable instead of create/destroy