Houdini 20.0 Shelf tools

Source from Surface shelf tool

Continuously generates smoke, fire, or liquid from the surface of an object.

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This tool continuously generates fluid from the surface of an object and is similar to Source from Points and Source from Volumes. Sourcing is done in a thin shell around the surface of the selected geometry. If sourcing into a pyro or smoke simulation, thickness of the shell can be controlled by adjusting Particle Separation on the Pyro Source node. With liquid simulations, the created FLIP Source SOP has a Shell Thickness parameter that directly controls its namesake.

The tool will create a setup tailored towards the simulation it is applied to. In case of a smoke simulation, it will import density and temperature, causing smoke to rise from the selected object. If applied to a pyro simulation, the shelf tool will inject fuel and temperature, turning the surface into a flame source. Finally, the tool will add the necessary nodes to continuously emit liquid into a FLIP simulation, similar to Emit Particle Fluid.


If you want the sourced smoke to inherit the object’s motion, you can use the Point Velocity SOP to calculate its velocity. The velocity attribute will then be transferred to the scattered points by the Pyro Source node and converted into a VDB by the Volume Rasterize Attributes SOP.

Using Source from Surface

  1. Create an open geometry object within a container.

    For more information on containers see: Smoke Container or Pyro Container.

  2. Select the geometry object to generate the source.

  3. Click the Source from Surface tool on the Populate Containers tab.

  4. Select the container to put the source into and press Enter to confirm your selection.


To turn off the continuous flow of fluid, set the Activation to 0 on the Volume Source node in your DOP network. You can keyframe this parameter to control when the fluid is emitted.


If the object is only partially in the container, only the portion of the object that is within the container’s boundaries will be simulated.

See also

Shelf tools

Using the shelf

  • Customize the shelf

    How to change the look of the shelf, change and rearrange its contents, and create your own shelf tools.