Emitter Attribute - Lumberyard User Guide

Emitter Attribute

In the Emitter attribute, specify how to control the location and spawning attributes of the particle and emitter shape. The parameters are updated based on the type that you select.

                Emitter attributes in the
                        Particle Editor.
Emitter Attribute Parameters
Name Description
Particle Type Specifies whether the emitter is a CPU or GPU type.
Emitter Shape Type Specifies the emitter shape type.
  • Angle – Standard emitter type based on angle parameters. This is the default value.

  • Point – Spherical distribution emitter.

  • Sphere – Sphere shape emitter with particles controlled along the sphere's circumference coordinates.

  • Circle – Circle shape emitter with particles controlled along the circumference and vertical coordinates.

  • Box – Box shape emitter with particles controlled along the planes of the box.

  • Trail – Emitter to create trail type effects.

  • Beam – Emitter to create beam type effects.


    If you change the Emitter Shape Type, the attributes will reset to the default settings for the selected emitter. In the confirmation message, you can select Do not prompt again. This prompt is reset when you select Reset to default layout.

Relative Particle Movement Determines the particle motion in the emitter's space. The following is an example of particles that are emitted upward from an emitter:
  • No – The emitted particles stay in world space and fall behind as the emitter moves away, for example, like smoke from the chimney of a train.

  • Yes – The emitted particles stay relative to the emitter's local space and won't fall behind as the emitter is moved. An example is a smoke column going straight up from the chimney and staying vertical with the emitter. This excludes tail particles.

  • Yes with Tail – The emitted particles stay relative to the emitter's local space, including any associated tail particles.

Default value: No

Parameter Inheritance Specifies the source for default (starting) effect parameters.
  • Standard (default) – Uses the values set in DefaultParticleEmitters.xml.

  • System (deprecated) – Reads the System.Default.xml file to use as defaults for the angle emitter. If this effect does not exist, you can use standard defaults. You can generate the .xml file by adding a library named System and an emitter named default. Save the library to your \<project>\libs\particles directory.

  • Parent – Uses the parent particle effect for defaults. This is useful when creating a parent effect with one set of parameters and a variety of subeffects that alter some of the parameters for variation. Subeffects can spawn on their own. Edit the parent effect to update the default values of all subeffects.

The selected source has the following consequences:

  • When you create a new effect, default parameters are set from the following file:


  • Changing the inheritance source does not change any other parameters. However, different parameters may be highlighted if their defaults have changed.

To reset parameters to the default values that are located in the DefaultParticleEmitters.xml file, right-click the parameter and choose Reset to default. You can modify the default values for the project using the same file.

When you save effects to .xml libraries, only non-default values are saved. When you load effects from the .xml libraries, the current default values for the effect's inheritance are used as a base.

When you edit a parent effect's parameters, the non-edited parameters of all children (and descendants) that have Parent selected are instantly updated.

Spawn Indirection

This parameter has the following values:

  • Direct – Spawns without relying on the parent's input for timing. This is the default value.

  • ParentStart – Spawns once the parent has spawned.

  • ParentCollide – Spawns a particle with this setting when the parent particle has collided with an object.

  • ParentDeath – Spawns a particle with this setting when the parent particle has lived out its lifetime.


This parameter is supported only within the same CPU or GPU particle type.

Attach Type Specifies the emission location when the parent emitter has geometry.
  • None – Particles ignore geometry and emit from the emitter center as normal.

  • Bounding Box – Particles emit from the object's bounding box.

  • Physics – Particles emit from the geometry of the attached physics object (mesh or simple primitive).

  • Render – Particles emit from the full mesh of the render object (static or animated mesh). This is generally more CPU-intensive than emitting from physics.

Default value: None

Attach Form Specifies the elements of the geometry from which particles emit.
  • None – Not active.

  • Vertices – Emits randomly from the vertices of the geometry. This is the most efficient form of mesh emission.

  • Edges – Emits randomly from the edges of the geometry. This is useful for effects on breaking element pieces.

  • Surface – Emits randomly from the surfaces (faces) of the geometry.

  • Volume – Emits randomly inside the volume of the geometry.

Default value: Vertices

Count Specifies the total number of particles that are active at a given time and determines the emission rate (Count/Particle Lifetime). You can set a Random value and the Strength Over Emitter Life curve.

Valid values: 0+

Maintain Density Increases the emission rate (and particle count) when an emitter moves in order to maintain the same spatial density as when motionless. You can scale the increase from 0 to 1.
  • Reduce Alpha – When Maintain Density is active, this reduces particle alpha in order to maintain the same overall emitter alpha.

Valid values: 0+

Continuous If false, emits all particles at once and then dies. If true, emits particles gradually over the emitter lifetime. If true and Emitter Lifetime = 0, emits particles gradually at a rate of Count/Particle Lifetime per second, indefinitely.

Default value: false

Spawn Delay Delays the start of the emitter for the specified time. This is useful to delay subeffects relative to the overall emitter creation time. Can set a Random value.

Valid values: 0+

Default value: 0

Emitter Lifetime If Continuous = true, specifies the lifetime of the emitter. Emitter lifetime does not apply to noncontinuous effects, which always disappear as soon as they have emitted all of their particles. You can set a Random value.

Valid values: 0+

Default value: 0 (infinite lifetime)

Pulse Period If greater than 0 and Continuous = false, restarts the emitter repeatedly at this interval. You can set a Random value.

Valid values: any

Default value: 0

Orient to Velocity Forces the particle x-axis to align to the velocity direction. You can use Rotation parameters to rotate the particle further.

Default value: false

Position Offset XYZ values define the spawning position away from the emitter itself in emitter space.

Valid values: any

Default values: 0, 0, 0

Random Offset XYZ values define the range of a random spawning box in both directions, away from the position offset.

Valid values: any

Default values: 0, 0, 0

Offset Roundness Specifies the fraction of spawning volume corners to round.

Valid values: 0 (box shape) to 1 (ellipsoid shape)

Default value: 0

Offset Inner Fraction Specifies the ratio of inner to outer spawning volume.

Valid values: 0 (spawn within entire volume) to 1 (spawn only at surface)

Default value: 0