Houdini 20.5 Shelf tools

Spreading Fire shelf tool

Creates a fire simulation spreading across the surface of the selected object.

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This tool sets up a spreading fire simulation from the selection. There are two stages to this simulation. First, the spreading behavior across the selected surface is captured with the help of the Pyro Source Spread SOP. The Pyro Solver (Sparse) node then accepts this base spreading as a source and creates the motion and look of spreading fire.

Understanding Spreading Fire

The created setup consists of the following three components.

  1. object_source takes care of the spreading simulation and preparation of the sources. The hot_region node specifies the starting point of the fire spread, and can be moved to the desired location of the initial spark. The simulate_spread node then captures the outward growth of the burning regions from this starting point.


    You should start by finalizing the spreading animation in this network before moving on to the pyro simulation.

  2. fire_simulation contains the dynamics network that consumes the spreading source and makes it look like fire. The parameters on the sparse pyro solver have the greatest influence on the motion and emergent shape of the fire.

    To...Do this

    Increase the speed of the flames

    Boost the Buoyancy Scale. This will also increase vertical size of the fire.

    Change the vertical size of the fire

    Adjust Flame Lifespan. The flame field will be reduced more slowly when value of this parameter is larger, resulting in higher flames.

    Change the motion of fire

    Experiment with Disturbance and Shredding. Disturbance generically breaks up the flames, whereas shredding redirects the velocities, creating the licks.

    Adjust brightness and color of the fire

    Modify the Emission Scale and Temperature Scale parameters on the pyro smoke object. These can be found in the Guides ▸ Multi Field ▸ Emission subtab.

  3. fire_import extracts results of the simulation into a SOP geometry. A pyro post-process node sets the proper viewport visualization settings and creates a matching render material.

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.