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Voids are used to remove Smoke and/or Fuel. You don’t necessarily need to remove them manually, and just set up smoke/fuel to dissipate. Also, Voids can create negative pressure, pulling smoke/fuel inside.
Right click in Hierarchy, and select “Zibra Smoke And Fire -> Void”.
Note that if you right click specifically on your Smoke And Fire object, as shown on the screenshot, you can skip step 2.
Open Inspector for your Smoke And Fire object, and press the Add button in the list of manipulators to add. You can also use the Add all button to add all manipulators to your Smoke And Fire instance.
You may also need to expand the list of colliders to add by pressing the “Add Manipulators” button first.
Color Decay
Controls how quickly the amount of smoke or fuel is decreasing. 1.0 will have no decay, 0.5 will remove half of the total density each simulation iteration.
Velocity Decay
Controls how quickly the velocity of the smoke or fire is decreasing each frame. 1.0 will have no decay, 0.5 will remove half of the velocity each simulation iteration.
Pressure
This parameter controls how much pressure to add to the given region. Negative values will suck in the smoke, positive values will move the smoke away.