Sub-emitters in Unity

Introduction

Sub-emitters let you create extra particle effects that start when main particles die or collide. This helps make effects look more natural and exciting.

When you want sparks to fly out after a firework explodes.

To create smoke puffs after a bullet hits a surface.

For adding small explosions after a big explosion fades.

When particles should trigger other effects on collision.

To chain particle effects for more complex visuals.

Syntax

Unity

ParticleSystem subEmitter = mainParticleSystem.subEmitters.AddSubEmitter(subEmitterPrefab, SubEmitterType.Birth, SubEmitterProperties.InheritColor);

Use SubEmitterType to decide when the sub-emitter triggers: on Birth, Collision, or Death of the main particle.

Sub-emitters are added to the main particle system's subEmitters property.

Examples

Adds a smoke effect that starts when each main particle dies.

Unity

mainParticleSystem.subEmitters.AddSubEmitter(smokePrefab, SubEmitterType.Death, SubEmitterProperties.None);

Adds sparks that appear when particles collide, inheriting the main particle's color.

Unity

mainParticleSystem.subEmitters.AddSubEmitter(sparkPrefab, SubEmitterType.Collision, SubEmitterProperties.InheritColor);

Creates a flash effect every time a new particle is born, inheriting its lifetime.

Unity

mainParticleSystem.subEmitters.AddSubEmitter(flashPrefab, SubEmitterType.Birth, SubEmitterProperties.InheritLifetime);

Sample Program

This script adds a sub-emitter to the main particle system. The sub-emitter plays its effect whenever a main particle dies, such as smoke or sparks. It then starts the main particle system.

Unity

using UnityEngine;

public class SubEmitterExample : MonoBehaviour
{
    public ParticleSystem mainParticleSystem;
    public ParticleSystem subEmitterPrefab;

    void Start()
    {
        // Add a sub-emitter that triggers when main particles die
        mainParticleSystem.subEmitters.AddSubEmitter(subEmitterPrefab, SubEmitterType.Death, SubEmitterProperties.None);

        // Start the main particle system
        mainParticleSystem.Play();
    }
}

Important Notes

Sub-emitters only work if the main particle system has subEmitters enabled.

Remember to assign the sub-emitter prefab in the Unity Editor or by script before adding it.

Sub-emitters can affect performance if overused, so use them wisely.

Summary

Sub-emitters create extra particle effects triggered by main particles.

They can start on particle birth, collision, or death.

Use them to make effects more dynamic and realistic.

Practice

1. What is the main purpose of sub-emitters in Unity's particle system?

easy

A. To change the color of particles over time

B. To control the speed of the main particle system

C. To pause and resume particle emission

D. To create extra particle effects triggered by main particles

Solution

1. Step 1: Understand sub-emitters role

   Sub-emitters are used to add extra effects that happen when main particles do something.

2. Step 2: Identify correct purpose

   They trigger new particles on events like birth, death, or collision of main particles.

3. Final Answer:

   To create extra particle effects triggered by main particles -> Option D

4. Quick Check:

   Sub-emitters = extra triggered effects [OK]

Hint: Sub-emitters add effects triggered by main particles [OK]

Common Mistakes:

• Thinking sub-emitters control particle speed
• Confusing sub-emitters with color changes
• Assuming sub-emitters pause emission

2. Which of the following is the correct way to add a sub-emitter in Unity's Particle System component?

easy

A. In the Particle System inspector, expand Sub Emitters and click '+' to add a sub-emitter

B. Add a new Particle System component to the same GameObject

C. Use the Animator window to link particle effects

D. Write a script to manually spawn particles without using sub-emitters

Solution

1. Step 1: Locate sub-emitter settings

   In Unity's Particle System inspector, there is a Sub Emitters section to manage sub-emitters.

2. Step 2: Add sub-emitter correctly

   You add a sub-emitter by clicking the '+' button inside that section to assign a particle system as sub-emitter.

3. Final Answer:

   In the Particle System inspector, expand Sub Emitters and click '+' to add a sub-emitter -> Option A

4. Quick Check:

   Sub Emitters panel '+' button = add sub-emitter [OK]

Hint: Use '+' in Sub Emitters section to add sub-emitters [OK]

Common Mistakes:

• Adding a separate Particle System component instead
• Trying to link particles via Animator window
• Spawning particles only by script without sub-emitters

3. Consider a particle system with a sub-emitter set to trigger on particle death. What happens when a main particle dies?

medium

A. The main particle system stops emitting particles

B. The sub-emitter changes the color of the main particle

C. The sub-emitter spawns its particles at the main particle's death position

D. Nothing happens because sub-emitters only trigger on birth

Solution

1. Step 1: Understand sub-emitter trigger types

   Sub-emitters can trigger on birth, death, or collision of main particles.

2. Step 2: Effect of death trigger

   When a main particle dies, the sub-emitter spawns its own particles at that exact position.

3. Final Answer:

   The sub-emitter spawns its particles at the main particle's death position -> Option C

4. Quick Check:

   Death trigger = spawn sub-particles at death spot [OK]

Hint: Death trigger spawns sub-particles at main particle's position [OK]

Common Mistakes:

• Thinking sub-emitters stop main emission
• Believing sub-emitters change main particle color
• Assuming sub-emitters only trigger on birth

4. You set up a sub-emitter to trigger on collision, but no sub-particles appear when main particles collide. What is the most likely cause?

medium

A. The sub-emitter particle system is not assigned in the Sub Emitters list

B. The main particle system has no collision module enabled

C. The sub-emitter is set to trigger on birth instead of collision

D. The main particle system's emission rate is zero

Solution

1. Step 1: Check collision module status

   For sub-emitters to trigger on collision, the main particle system must have collision enabled.

2. Step 2: Identify cause of no sub-particles

   If collision is off, no collision events happen, so sub-emitters won't trigger.

3. Final Answer:

   The main particle system has no collision module enabled -> Option B

4. Quick Check:

   Collision off = no collision trigger for sub-emitters [OK]

Hint: Enable collision module for collision-triggered sub-emitters [OK]

Common Mistakes:

• Not assigning sub-emitter particle system
• Setting wrong trigger type
• Having zero emission rate but expecting collisions

5. You want to create a firework effect where each main particle explodes into smaller sparks on death, and each spark also creates a small smoke puff on its own death. How do you set this up using sub-emitters?

hard

A. Add a sub-emitter to the main particle system triggered on death for sparks, then add a sub-emitter to the sparks system triggered on death for smoke

B. Add all effects as sub-emitters to the main particle system triggered on birth

C. Use only one particle system with color changes to simulate sparks and smoke

D. Spawn sparks and smoke manually via script without sub-emitters

Solution

1. Step 1: Setup main particle system with death-triggered sparks

   Add a sub-emitter to the main system that triggers on death to spawn spark particles.

2. Step 2: Setup sparks particle system with death-triggered smoke

   Add a sub-emitter to the sparks system that triggers on death to spawn smoke puffs.

3. Step 3: Chain sub-emitters for layered effects

   This chaining creates the firework effect with sparks and smoke triggered sequentially.

4. Final Answer:

   Add a sub-emitter to the main particle system triggered on death for sparks, then add a sub-emitter to the sparks system triggered on death for smoke -> Option A

5. Quick Check:

   Chain death-triggered sub-emitters for layered effects [OK]

Hint: Chain sub-emitters triggered on death for multi-layer effects [OK]

Common Mistakes:

• Adding all effects on birth triggers only
• Using one system with color changes only
• Avoiding sub-emitters and scripting manually