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With "No", particles will be removed inside the volume, with "Yes", this happens outside.
Shape
Choose from three predefined shapes ("Box", "Sphere", "Plane"), or select an "Object" for deleting particles – this action unlocks the option's associated parameters.
Objects
Only available with "Shape" set to "Object". Choose at least one object to remove particle from its inside or outside.
Object offset
This option creates a buffer around the object to inflate (> 0) or shrink (< 0) the object's volume. The value is measured in metres.