【Unity】Mastering Unity's Reuse System: Prefabs - Efficient Object Duplication and Management

Overview

When developing games in Unity, you'll inevitably want to reuse the same configured objects multiple times—enemy characters, bullets, coins, background objects like trees and rocks. Manually copy-pasting each object placement is tedious, and when you later decide "I want to slightly change enemy HP," modifying every enemy in the scene becomes a nightmare.

Prefabs elegantly solve this problem and are one of Unity's most powerful and important features. A Prefab is like a "blueprint" or "template" that bundles a GameObject with its components and property settings. This article covers everything from basic Prefab concepts to creation, usage, and advanced techniques for maximizing development efficiency.

What Is a Prefab?

A Prefab is a reusable GameObject asset. Create and configure a GameObject in the Hierarchy window, then simply drag-and-drop it into the Project window to create a Prefab.

Once Prefab-ized, you can place (instantiate) that Prefab asset in scenes like a stamp, as many times as needed. The most powerful aspect: when you modify the original Prefab asset (blueprint), changes automatically propagate to all instances (scene objects) created from it.

Benefits of Using Prefabs

Reusability: Easily place the same object in scenes repeatedly.
Batch Editing: Edit the original Prefab to update all instances simultaneously. This creates projects that are resilient to specification changes and highly maintainable.
Dynamic Generation: Use Instantiate() to dynamically create objects from Prefabs during gameplay. Essential for bullet firing, enemy spawning, etc.

Creating and Using Prefabs

1. Creating Prefabs

Prepare the Object: Create the GameObject you want to Prefab-ize in the Hierarchy, add necessary components (scripts, Colliders, etc.), and configure values in the Inspector.
Prefab-ize: Drag the configured GameObject from Hierarchy to any folder in the Project window (commonly create a Prefabs folder).

This creates a Prefab asset with a blue cube icon in the Project window. Simultaneously, the original object in Hierarchy changes to a blue icon, indicating it's now a Prefab instance.

2. Instantiating (Placing) Prefabs

Manual Placement: Drag Prefab assets from Project to Scene view or Hierarchy.
Dynamic Generation: Use Instantiate() from scripts.

using UnityEngine;

public class Spawner : MonoBehaviour
{
    // Prefab set in Inspector
    public GameObject enemyPrefab;

    void Start()
    {
        // Start coroutine spawning enemies every 3 seconds
        StartCoroutine(SpawnEnemies());
    }

    IEnumerator SpawnEnemies()
    {
        while (true)
        {
            // Create new instance from Prefab
            Instantiate(enemyPrefab, transform.position, Quaternion.identity);
            yield return new WaitForSeconds(3f);
        }
    }
}

Editing Prefabs and Overrides

Editing Prefabs

Edit Prefab assets by:

Prefab Mode: Double-click the Prefab asset in Project, or select a Prefab instance in Hierarchy and click "Open" in Inspector to enter dedicated "Prefab Mode." Changes made here affect all instances.

Overrides

Sometimes you want to change only specific instances from Prefab settings—"give this enemy more HP" or "make this tree bigger."

When you change values on a scene Prefab instance in Inspector, those properties display in bold, indicating they're overridden. These changes apply only to that instance—the original Prefab and other instances are unaffected.

To apply overrides to the original Prefab, select Apply All from the Overrides dropdown at the top of Inspector. To discard overrides and revert to Prefab settings, select Revert All.

Advanced: Nested Prefabs and Prefab Variants

Unity 2018.3 made Prefabs even more powerful:

Nested Prefabs: Put Prefabs inside other Prefabs. For example, create a "Gun" Prefab and incorporate it into a "Soldier" Prefab. This enables more modular component assembly.
Prefab Variants: Create "variant" Prefabs based on another Prefab, storing only the differences. For example, base "Normal Goblin" Prefab → "Red Goblin" variant (only material color differs), "Goblin Archer" variant (carries a bow). When you change HP on the base "Normal Goblin," that change inherits to all variants—extremely efficient management.

Summary

Prefabs embody object-oriented thinking in Unity and are fundamental for efficient, scalable game development.

Prefabs are reusable object "blueprints."
Edit the original Prefab to batch-update all instances.
Instantiate() dynamically generates objects during gameplay.
Overrides let you modify specific instances only.
Variants efficiently manage differential Prefabs inheriting from base Prefabs.

Making a habit of managing all in-game objects (players, enemies, items, UI elements) as Prefabs is a major step toward advancing beyond beginner level.

Menu