Explosion VFX & Destruction System Study

Description

This project focuses on creating a realistic explosion VFX in Unreal Engine 5, and combining it with UE5’s built-in Chaos Fracture system to simulate realistic destruction effects. The goal was to explore how to sync explosive visuals with mesh breaking behavior, resulting in a dynamic and cinematic VFX scene.

Result

Workflow Overview

Used the Chaos System to create a pre-fractured ground mesh
Applied a radial force field to trigger the fracture and simulate debris scattering after the explosion
Created custom explosion VFX and smoke trail VFX for flying debris
Controlled the entire sequence using a Blueprint-triggered explosion
Added animation timing to present the final explosion as a cinematic moment

Chaos System

Fracture Setup – Chaos Hierarchical Clustering

1. Hierarchical Fracture Levels

Set up multiple fracture layers:
- Level 0: Whole ground mesh
- Level 1: Break into large chunks
- Level 2+: Further subdivide into smaller pieces

2. Clustering with Auto Mode

Used Cluster → Auto to automatically organize fragments into levels
Level 1: Cluster Sites = 200
Level 2: Auto-generated from remaining pieces
Level 3: Cluster Sites = 75
Level 4: Cluster Sites = 50

Damage Settings for Fracture Activation

In the Details → Damage panel:

Each Index corresponds to a fracture level
Index 0 applies damage to Level 1, Index 1 to Level 2, and so on

Since there are 4 fracture levels, set up Index 0–3 to control how each layer reacts to impact or force

Performance Optimization

Used Tiny Geo to merge extremely small fragments, reducing overall complexity
Before optimization: 1500+ fragments
After optimization: 914 fragments, significantly improving performance

Chaos System - Force Field

FS_MasterField

UE5 Blueprint force field that applies custom directional forces to fractured meshes
In Field Settings, enable Apply Directional Vector to push debris upward
Adjust Magnitude to control the explosion force strength

FS_SleepDisable_Generic

After the explosion, debris may keep shaking due to ongoing force influence
This Blueprint helps stabilize debris by applying a sleep condition
Set to Sleep Mode: fragments entering the field will stop simulating once below a motion threshold

Explosion VFX & Smoke Trail VFX

To create a explosion effect, the following emitters were used:

Multiple Flame Emitters – for explosive bursts of fire
1 Smoke Emitter – for post-blast lingering smoke
2 Spark Emitters
1. One for mid-air sparks that quickly fade out
2. One for ground sparks that fall and slowly burn out
Multiple Debris Emitters – to simulate explosive debris flying outward

$fracture&explosion emitters result.png$

In this project, I explored two ways to make one emitter follow another:

Spawn Particles from Other Emitter

Directly spawns particles from the location of another emitter

2 methods to realize the particle follow_1.png

2 methods to realize the particle follow_event handler.png

Event Handler Method

In the source emitter (A): add a Generate Location Event
In the following emitter (B):
- Add an Event Handler module
- Set it to Receive Location Event from emitter A
This allows emitter B to dynamically follow emitter A’s particle locations