Unreal Engine 5 Documentation has been moved to the Epic Developer Community

Unreal Engine 4.26

Unreal Engine 4.27

Unreal Engine 5.0

Unreal Engine 5.1

Unreal Engine 5.2

Unreal Engine 5.3

> Designing Visuals, Rendering, and Graphics > Cascade Particle Systems > Particle System Reference > Event Modules

Light Theme

Dark Theme

Event Modules

Event modules allow you to generate events based on particles themselves or other actors in the level.

Choose your operating system:

Windows

macOS

Linux

On this page

Event Generator
Event Receiver Kill All (EventRcvr KillAll)
Event Receiver Spawn (EventRcvr Spawn)

Event modules allow you to generate events based on particles interacting with themselves, each other, or the world, and then listen for those events and cause reactions to them on an inter-particle system level. A good example is generating a named collision event whenever a particle collides with the world, and then spawning particles wherever those collisions occur.

Event Generator

The Event Generator module will generate an event (or multiple events) based on conditions you specify. This module has a single Events array that contains a list of all events you want the emitter to be able to generate. Each item in the Events array has the following properties:

Property

Description

Events

Type

The type of event. The possible types include:


Type	Description
EPET_Any	Generate a named event from any of the possible event occurrences.
EPET_Spawn	Generate the named event whenever a particle in this emitter spawns.
EPET_Death	Generate the named event whenever a particle in this emitter dies.
EPET_Collision	Generate the named event whenever a particle in this emitter collides with something.
EPET_Burst	Generate a particle burst event.
EPET_Blueprint	Generate an event which talks to Blueprints, allowing you to execute Blueprint script or allow Blueprint script to execute particle commands.

Frequency

How often to trigger the event. <=1 means every time. Use this to trigger an event on every other collision, say.

First Time Only

Boolean to trigger the event only on the first time it would fire.

Last Time Only

Boolean to trigger the event only on the last occurrence of when it would fire.

Use Reflected Impact Vector

Boolean to decide whether you orient the result of the collision event in the direction of the impact vector instead of the hit normal.

Custom Name

This is the name of your event, which allows you to set up a listener to listen for this event name and then act accordingly. All events need to be named.

Particle Module Events To Send To Game

The events we want to fire off when this event has been generated. Requires your game to implement new subclasses of ParticleModuleEventSendToGame representing the types of game events particle events should be able to trigger.

Event Receiver Kill All (EventRcvr KillAll)

EventReceiver Kill All listens for a named event and then kills all the particles of the emitter.

Property

Description

ParticleModuleEventReceiverKillParticles

Stop Spawning

If true , the emitter will cease spawning new particles in addition to killing all existing particles.

Events

Event Generator Type

What type of event to listen for.


Type	Description
EPET_Any	Generate a named event from any of the possible event occurrences.
EPET_Spawn	Generate the named event whenever a particle in this emitter spawns.
EPET_Death	Generate the named event whenever a particle in this emitter dies.
EPET_Collision	Generate the named event whenever a particle in this emitter collides with something.
EPET_Burst	Generate a particle burst event.
EPET_Blueprint	Generate an event which talks to Blueprints, allowing you to execute Blueprint script or allow Blueprint script to execute particle commands.

Event Name

The name of the event to listen for.

Event Receiver Spawn (EventRcvr Spawn)

EventReceiver Spawn listens for a named event and then spawns particles based on what events fire.

Property

Description

Spawn

Spawn Count

Determines how many particles to spawn when an event fires.

Use Particle Time

For Death-based event receiving, if this is true , it indicates that the ParticleTime of the event should be used to look-up the SpawnCount. Otherwise (and in all other events received), use the emitter time of the event.

Location

Use PSys Location

Boolean to decide whether the spawn event happens at the event of the particle that triggered the event, or at the origin of the particle system.

Velocity

Inherit Velocity

If true , the velocity of the particle that triggers the event will be used as the starting velocity of the spawned particle.

Inherit Velocity Scale

Multiplier for scaling the velocity if Inherit Velocity is true .

Source

Event Generator Type

What type of event to listen for.


Type	Description
EPET_Any	Generate a named event from any of the possible event occurrences.
EPET_Spawn	Generate the named event whenever a particle in this emitter spawns.
EPET_Death	Generate the named event whenever a particle in this emitter dies.
EPET_Collision	Generate the named event whenever a particle in this emitter collides with something.
EPET_Burst	Generate a particle burst event.
EPET_Blueprint	Generate an event which talks to Blueprints, allowing you to execute Blueprint script or allow Blueprint script to execute particle commands.

Event Name

The name of the event to listen for.