【Unity】Unity Particle System Introduction: Creating Fire, Smoke, and Magic Effects

Overview

Explosion smoke, sword trails, magic incantations, item sparkles—Visual Effects (VFX) are essential for making game worlds feel alive and exciting. Unity includes the Particle System as a powerful standard tool for creating these VFX. Due to its versatility, this system is nicknamed "Shuriken."

The Particle System generates countless small 2D images (particles) and enables diverse expressions by changing their movement, color, size, and lifetime over time. While there are many settings, understanding the roles of basic modules lets you combine them to create various effects.

This article covers the basic structure of Unity's Particle System and how to use its main modules.

Creating Particle Systems and Basic Structure

To create a Particle System, select GameObject > Effects > Particle System from the menu. This creates a new GameObject with a Particle System component attached.

The Particle System component Inspector consists of many modules. Each module is a collection of properties controlling specific particle aspects (e.g., emission, movement, color). Enable features by checking the checkbox on the left of each module.

Main Module

This always-enabled base module sets the most important particle properties:

• Duration: Total time the particle system plays the effect. Ignored if Looping is on.
• Looping: When enabled, the effect repeats after Duration elapses.
• Start Lifetime: Time (seconds) from particle creation to disappearance. Random values (e.g., Random Between Two Constants for 1-2 seconds) create more natural appearances.
• Start Speed: Initial speed when particles spawn.
• Start Size: Initial particle size.
• Start Color: Initial particle color. Random Between Two Colors mixes multiple colors.
• Gravity Modifier: Gravity strength applied to particles. 0 is weightless, positive pulls down, negative pushes up.

Key Module Overview

Beyond the Main Module, combine these modules for more complex effects:

Emission

Controls how frequently particles spawn.

• Rate over Time: Particles per second. Use for continuous smoke or rain.
• Bursts: Release a batch of particles at specific times. Use for explosions or attack hit effects.

Shape

Defines the area/shape from which particles emit.

• Shape: Choose from Sphere, Cone, Box, Edge, etc. For example, campfires use an inverted Cone, gun muzzle flashes use a narrow Cone.

Velocity over Lifetime

Changes particle velocity throughout their lifetime. Create swirling motions (Orbital) or attraction to specific points.

Color over Lifetime

Changes particle color throughout lifetime. Use the Gradient Editor to express color transitions like flames—"glow white at creation, gradually turn red, then black before disappearing."

Size over Lifetime

Changes particle size throughout lifetime. Use the Curve Editor for expressions like smoke—"start small, gradually grow, then shrink rapidly before disappearing."

Renderer

Configures how each particle is drawn.

• Material: Specifies the material for particles. Typically use materials with shaders supporting semi-transparent rendering like Particles/Standard Unlit.
• Render Mode: Billboard (2D planes always facing the camera) is most common. Stretched Billboard stretches particles in their movement direction—suitable for sparks or rain.

VFX Graph vs Particle System

Unity also offers the newer, more powerful VFX Graph (Visual Effect Graph). VFX Graph maximizes GPU capabilities, simulating millions of particles in real-time. Building effects with node-based graphs enables very complex, interactive expressions.

• Particle System (Shuriken): CPU-based. Relatively lightweight, suitable for thousands of particles. Simpler settings, easier for beginners. Widely used for mobile games and moderate effects.
• VFX Graph: GPU-based. Handles massive particle counts, suited for high-end PC/console effects. Higher learning curve than Shuriken.

Summary

The Particle System holds infinite possibilities through module combinations.

• Particle Systems are collections of many modules.
• Main Module sets basics—particle lifetime, speed, size, color.
• Emission defines spawn rate; Shape defines emission shape.
• Color over Lifetime and Size over Lifetime express time-based changes.
• Renderer module sets particle appearance (material).

Start by mimicking existing effects or experimenting with various module properties. Through trial and error, you'll understand how parameters interact and create effects exactly as envisioned.