Sub-emitters in Unity - Step-by-Step Execution

Concept Flow - Sub-emitters

Start Particle System

↓

Emit Main Particles

↓

Check Sub-emitter Trigger

↓

Emit Sub-emitter

↓

Sub-emitter Particles

↓

End

The main particle system emits particles. When a particle event occurs (like birth or death), the sub-emitter triggers and emits its own particles.

Execution Sample

Unity

void OnParticleTrigger() {
  var sub = mainParticleSystem.subEmitters;
  sub.EmitSubEmitter(0, 5);
}

When the main particle system triggers, it emits 5 particles from its first sub-emitter.

Execution Table

Step	Action	Main Particle Count	Sub-emitter Triggered	Sub-emitter Particle Count
1	Start main particle system	0	No	0
2	Main system emits 3 particles	3	No	0
3	Particle event triggers sub-emitter	3	Yes	0
4	Sub-emitter emits 5 particles	3	Yes	5
5	Main system emits 2 more particles	5	No	5
6	No new trigger, particles continue	5	No	5
7	End of simulation	5	No	5

💡 Simulation ends after fixed steps; no more triggers.

Variable Tracker

Variable	Start	After Step 2	After Step 4	After Step 5	Final
Main Particle Count	0	3	3	5	5
Sub-emitter Particle Count	0	0	5	5	5
Sub-emitter Triggered	No	No	Yes	No	No

Key Moments - 2 Insights

Why does the sub-emitter only emit particles after a trigger event?

Sub-emitters are designed to emit particles only when a specific event occurs in the main system, like particle birth or death, as shown in step 3 and 4 of the execution_table.

Does the main particle count increase when the sub-emitter emits particles?

No, the main particle count and sub-emitter particle count are tracked separately, as seen in steps 4 and 5 where main count stays at 3 while sub-emitter emits 5 particles.

Visual Quiz - 3 Questions

Look at the execution_table, at which step does the sub-emitter first emit particles?

A Step 4

B Step 3

C Step 2

D Step 5

💡 Hint

Check the 'Sub-emitter Particle Count' column for when it changes from 0 to 5.

According to variable_tracker, what is the main particle count after step 5?

A 3

B 5

C 0

D 8

💡 Hint

Look at the 'Main Particle Count' row under 'After Step 5' column.

If the sub-emitter trigger never happens, what would the sub-emitter particle count be at the end?

A 5

B 3

C 0

D Cannot determine

💡 Hint

Refer to the 'Sub-emitter Particle Count' column in execution_table rows where 'Sub-emitter Triggered' is 'No'.

Concept Snapshot

Sub-emitters are particle systems triggered by events in a main particle system.
They emit particles only when triggered (e.g., on birth or death).
Main and sub-emitter particles are tracked separately.
Use subEmitters.EmitSubEmitter(index, count) to emit.
Useful for effects like sparks from explosions.

Full Transcript

This visual execution shows how a main particle system emits particles and triggers a sub-emitter to emit its own particles. The flow starts with the main system emitting particles. When a trigger event occurs, the sub-emitter activates and emits particles separately. The execution table tracks particle counts and trigger states step-by-step. Key moments clarify that sub-emitters only emit on events and do not increase main particle counts. The quiz tests understanding of when sub-emitters emit and particle counts at various steps. The snapshot summarizes usage and behavior of sub-emitters in Unity particle systems.