Houdini 18.0 Nodes Dynamics nodes

Whitewater Emitter dynamics node

A POP solver that generates particles for the Whitewater Solver.

This node type is deprecated. It is scheduled to be deleted in an upcoming revision of Houdini.

(Since version 17.0.)

The Whitewater Emitter emits volumetric particle clouds based on the input from a SOP Source, usually a Whitewater Source node. It is designed to be used as input to the Whitewater Solver.



This operator has two methods for emitting particles. You can use these methods together or separately:

  • Impulse creates a certain number of particles for each input particle each time the node cooks.

  • Constant creates a certain number of particles per input particle per second.

Impulse Count

Number of particles to emit each time the node cooks.

Const. Birth Rate

Number of particles to emit per second.

Emission Attribute

The specified attribute can be used to control whether a point is replicated or not. This attribute should be a float value to represent the probability of replicating the source point.


The seed used to generate random particle clouds.

Just Born Group

Name of a group to put the new points into. The particles will only be in this group the same substep that they were created.

Life Expectancy

How long the particle will live (in seconds).


When used as input to the Whitewater Solver, the Life Expectancy will typically be overwritten for each different particle type as specified in the solver.

Life Variance

Particles will live the number of seconds in Life expectancy, plus or minus this number of seconds. Use 0 for no variance.



The shape of the generated point cloud before transformation to each input point.

Velocity Offset

The distance along the velocity vector to replicate the particles, ranging from 0 at the beginning of the velocity vector to 1 at the end.

Velocity Stretch

A scale applied to the input point speed before stretching the particle clouds along the velocity vector.

Uniform Scale

A uniform factor applied to the replicated point cloud scale, in addition to any scaling attributes on the input points.


Add Noise

Add noise to the replicated point cloud in local space. The noise will respect the input point’s rest attribute if present.

Noise Type

Specifies the noise type.


The scale of the noise. Decreasing frequency increases feature size.


Allows the noise field to be effectively moved through space.


The amplitude of the noise.


The amplitude reduction of higher frequency noise contributions.


Raises the noise to the given exponent.


The number of noise generations to use.


The parameters on this tab let you control which and how attributes are initialized on the emitted particles.

Initial Velocity

How to set the initial velocity of the emitted particles.

Use inherited velocity

Use the inherited velocity attribute as the initial velocity of the particles.

Add to inherited velocity

Add the inherited velocity attribute to the values from the Velocity and Variance parameters below.

Set initial velocity

Set the initial value of the velocity attribute using the Velocity and Variance parameters below.

Inherit Velocity

When Initial velocity is Use inherited velocity or Add to inherited velocity, this is the proportion of the inherited velocity to use. Use 1 for the full inherited value, 0.5 to half the inherited value, and so on.

Radial Velocity

The proportion of the velocity in the radial direction to inherit.


Set or add to velocity attribute.


Variance to velocity set above. The node will add +/- from 0 to this number along each axis to the Velocity parameter.


Dynamics nodes