This tool sets up a spreading fire simulation from the selection. Rather than building a DOP network, it uses the SOP-level tools to build a simple network to work with sparse pyro.

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 SOP then accepts this base spreading as a source and creates the motion and look of spreading fire.

1. Click the Simple Spreading Fire tool on the Simple FX tab.

2. Select the surface object to spread fire across in the viewport, and press Enter to accept the selection.

• If you have a Houdini FX License, you can dive inside the solver and edit the subnet with custom DOP forces. Otherwise, you can stay at the SOP level and use the exposed parameters on the node.

• 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 captures the outward growth of the burning regions from this starting point.

  Tip

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

• The parameters on the Pyro Solver SOP have the greatest influence on the motion and emergent shape of the fire.