Generates a volumetric shape in the grid, with 0 value on the surface, positive values increasing into the center and negative values extending outwards.

Shape:                        Shape of the volume being generated. If plane is chosen, additional options are displayed for what axis to use.
Center:                       Centerpoint for the shape to generate on. The point is in object space unless world space is ticked on.
Size:                            Shape is generated inside a sphere of radius size.
Scale:                          Scalar value for each axis.
Positive Density:       Multiplier for the positive density values.
Negative Density:     Multiplier for the negative density values.
Positive Add:             Value added to the positive side after multiplication.
Negative Add:           Value added to the negative side after multiplication.
Operation:                 Method by which the effect is blended with the existing density value.
Mix:                            Dissolve between the original image at 0 and the full effect at 1.