Lifted from the Houdini help page.. Useful for localised noise/breakup
You can attach DOP nodes that modify velocity fields, such as Gas Turbulence, to the fourth ("Advection") input of the Pyro solver node. Most field-modifying nodes have some way to scale the effect by a mask field.
Create a geometry object in the shape of the area you want to affect.
Convert geometry to a fog volume - use an isooffset
In the DOP network, add a SOP Scalar Field node after the Pyro object.
- Turn on Use SOP Dimensions.
- Set the SOP path to the path of the fog volume object (for example
/obj/mask_object). Make sure Use Object Transform is on. - Set the Data Name to something indicating the purpose of this field, for example
NoiseMask.
This attaches the fog volume as field data on the Pyro object with the given name.
Create a Gas Turbulence node and connect it to the fourth ("Advection") input of the Pyro solver.
- On the Bindings tab, set the Density Field to the name of the mask data, for example
NoiseMask. The effect of the node is multiplied by the value of this field. - Use the controls on the Turbulence Settings tab to control the amount of turbulence added.
