Particle System component in Unity - Step-by-Step Execution

Concept Flow - Particle System component

Create Particle System

↓

Set Emission Rate

↓

Configure Particle Properties

↓

Play Particle System

↓

Particles Emit & Animate

↓

Particles Die & Loop or Stop

This flow shows how a Particle System is created, configured, played, and how particles emit, animate, and eventually die or loop.

Execution Sample

Unity

var ps = gameObject.AddComponent<ParticleSystem>();
var emission = ps.emission;
emission.rateOverTime = 10f;
ps.Play();

This code adds a Particle System to a game object, sets the emission rate to 10 particles per second, and starts the particle emission.

Execution Table

Step	Action	Particle System State	Emission Rate	Particles Emitted	Notes
1	Add ParticleSystem component	Stopped	0	0	Particle system created but not playing
2	Set emission rate to 10	Stopped	10	0	Emission rate configured but no particles emitted yet
3	Call Play()	Playing	10	0	Particle system starts emitting particles
4	After 0.1 seconds	Playing	10	1	Approximately 1 particle emitted (10 per second)
5	After 0.5 seconds	Playing	10	5	Approximately 5 particles emitted
6	After 1 second	Playing	10	10	Approximately 10 particles emitted
7	Stop called	Stopped	10	10	Emission stops, existing particles remain until lifetime ends
8	Particles die after lifetime	Stopped	10	0	All particles disappeared, system idle

💡 Particle system stops emitting when stopped and all particles have died.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 6	After Step 8
ParticleSystem State	None	Stopped	Playing	Playing	Stopped
Emission Rate	0	10	10	10	10
Particles Emitted	0	0	0	10	0

Key Moments - 3 Insights

Why are no particles emitted immediately after setting the emission rate?

Because the particle system is still stopped (see Step 2 in execution_table). Particles only emit when Play() is called.

What happens to particles after Stop() is called?

Emission stops immediately but existing particles remain until their lifetime ends (see Step 7 and 8).

Does changing emission rate affect already emitted particles?

No, emission rate controls new particles emitted per second, existing particles continue their lifecycle unchanged.

Visual Quiz - 3 Questions

Look at the execution_table, what is the Particle System State at Step 3?

A Paused

B Playing

C Stopped

D Destroyed

💡 Hint

Check the 'Particle System State' column at Step 3 in execution_table.

At which step does the particle system stop emitting new particles?

A Step 7

B Step 6

C Step 4

D Step 8

💡 Hint

Look for the step where the state changes to 'Stopped' but particles still exist.

If emission rate was set to 20 at Step 2, how many particles would be emitted after 0.5 seconds?

A 5

B 20

C 10

D 0

💡 Hint

Emission rate is particles per second; multiply by time (0.5s) to estimate emitted particles.

Concept Snapshot

Particle System component in Unity:
- Add component to GameObject
- Set emission rate (particles per second)
- Call Play() to start emitting
- Particles animate and die after lifetime
- Stop() halts emission but particles remain until dead

Full Transcript

This visual execution shows how a Particle System component in Unity works step-by-step. First, the system is added and is stopped with zero emission. Then the emission rate is set but no particles emit until Play() is called. Once playing, particles emit over time based on the emission rate. When Stop() is called, emission stops but existing particles continue until their lifetime ends. Variables like Particle System State, Emission Rate, and Particles Emitted change over time as shown in the tables. Key moments clarify common confusions about when particles emit and what happens after stopping. The quiz tests understanding of these steps.