Houdini 20.0 Nodes Geometry nodes

FLIP Source geometry node

Creates a surface or density VDB for sourcing FLIP simulations.

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Since 17.0

The FLIP Source SOP converts its input geometry into a volume that can be used to control simulations. For instance, the generated volume can be used to inject liquid into a FLIP simulation or act as a sink in a smoke simulation. In either case, this node can be used in conjunction with the Volume Source DOP to affect simulations. This node includes several presets to simplify initialization of the operator for common use cases.


Geometry to Source From

Input geometry to convert into a volume.



Generated volume and particles (if Create Particles is enabled).



Configures the node according to the selected preset.

Volume Name

Name of the VDB that is to be created.


If the incoming geometry has a signed distance field whose name is the same as the value of Volume Name, it will be used directly. Otherwise, a signed distance field is created for the geometry.

Voxel Size

Voxel size of the created VDB.

Shell Thickness

Enabling this option interprets the input geometry as a shell around its surface of the given thickness (as opposed to a filled volume).

Output Fog

When this option is turned on, a fog VDB is generated instead of a signed distance field.

Fog Boost

Enabling this option remaps the generated fog VDB, boosting its values towards 1.

Create Particles

Seed particles inside of the geometry.

Particle Group

The created points are organized into a group of this name.

Particle Separation

The distance between generated particles.

Jitter Seed

Random seed for creating jitter.

Jitter Scale

The amount of jitter to apply to the positional values of the particles.


The amount to oversample the points within a distance from the zero isosurface of the SDF volume, as specified by the Oversampling Bandwidth.

Oversampling Bandwidth

The points will be oversampled to this distance from the zero isosurface of the SDF volume. This parameter is specified in multiples of Particle Separation.

Radius Attribute

When enabled, the seeded particles will have a point attribute of the given name to store particle radii. The saved value is equal to Particle Separation.


When enabled, the seeded particles are endowed with the given velocity (stored in the v point attribute).

Add Rest Attribute

Creates a rest attribute set to the particle’s current position offset by the vector specified in Rest Offset.

Dual Rest Attributes

Creates a rest2 attribute in addition to the rest attribute, usually used in conjunction with the FLIP solver’s support for Dual Rest Attributes.

Rest Offset

Offset the current position by this vector before storing in the rest attributes.

See also

Geometry nodes