Trails and Sub-Emitters

Birth, tick, collision, and death events can chain emitters into multi-stage effects such as this firework.

The Particle Emitter can create secondary geometry and secondary emitters from each particle. These systems are powerful because they inherit particle state, but they also multiply simulation and rendering work.

Particle Trails

Enable Trails to attach a trail to a configured ratio of particles.

Setting	Purpose
ratio	Fraction of spawned particles that receive a trail.
lifetime	Trail lifetime function.
dieWithParticles	Remove the trail with its owner or let it drain.
sizeAffectsWidth	Multiply width by particle size.
sizeAffectsLifetime	Multiply trail lifetime by particle size.
inheritParticleColor	Multiply trail color by particle color.
colorOverLifetime	Color across trail life.
trailType	Select the trail implementation/render geometry.

The trail has its own material/renderer path. A Particle Emitter may therefore queue tile particles and trail particles into different effective render passes.

Sub-Emitter Events

Event	Trigger
Birth	Parent particle is created.
Death	Parent particle finishes its lifetime, or a collision rule removes it. A collision death carries the contact point.
Collision	Parent particle makes a fresh impact with a solid surface. Resting on a surface does not fire it again.
FirstCollision	Parent particle makes its first impact.
Tick	Repeats at the configured tick interval.
TriggerEnter	Parent particle enters a trigger collider, or an entity in Trigger mode.
TriggerExit	Parent particle leaves a trigger.

Since 2.2.9 TriggerEnter and TriggerExit.Changed 2.2.9 Collision fires once per fresh impact. Before 2.2.9 it could fire again on every tick a particle stayed blocked.

Which impacts and collision deaths are reported depends on the emitter's collision Events options (Min Impact Speed, De-duplicate).

Each entry includes target emitter reference, event, probability, tick interval, and inheritance flags for color, size, rotation, lifetime, and duration. Entries also have contact options for collision, trigger, and death events:

Since 2.2.9

Setting	Default	Meaning
Spawn At Contact	on for new entries	Spawn where the particle touched, not at its centre. Entries saved before 2.2.9 keep spawning at the centre.
Align To Normal	off	Turn the spawned effect so its +Y follows the surface normal.
Surface	Any	Fire only for contacts with Blocks, Fluids, Entities, or Colliders. A Death without a contact never passes a filter other than Any. Birth and Tick ignore it.
Surface Blocks	empty	With Blocks or Fluids: only these blocks, as ids or #tags. Empty means any.

See Particle Collision for how contacts become events.

Search and References

Sub-emitters reference another emitter in the same FX runtime. Use clear, unique names and keep the target in a sensible hierarchy location. Photon resolves and caches target searches, including large hierarchies.

Avoid Recursive Explosions

An emitter that spawns itself, or two emitters that spawn each other, can grow without bound. Probability and interval do not make an accidental cycle safe. Design an acyclic chain and set conservative max-particle counts.

Parallel updates

Sub-emitter requests created on worker updates are queued and applied safely by the owning emitter. Custom code must not directly mutate another emitter's particle collections from a worker thread.