9

ProBoolean Compound Object 381
The result is the intersection of the sphere and
thebox;thatis,asingleobjectthatrepresents
the common volume both objects occupy. In
this case, it’s the overlap of the sphere and the
box. Although neither has a mater ial at this
point, the result uses the default color originally
assigned by the software, at random, to the box
when it was created.
Note t hat Star t Picking stays active (yellow).
This means you can continue picking objects to
incorporate into the Boolean object, optionally
changing the operation as you go.
6. Set Operation to Union, and then click the
small box.
The result is the union (adding) of the small
box with the intersection of the sphere and
larger box. Again, the original object’s color is
assigned to the result.
7. Set Operat ion to Subtraction, and then click
the cylinder.
Thecylinder’sintersectingvolumeissubtracted
from the previous Boolean result.
Note that the entire histor y of operands
and operations used to build the Boolean
object is listed in the hierarchy view list at
the bottom of the Parameters rollout. Box01
starts the Boolean with Union, Sphere01 is
then incorp orated with Intersection, Box02
is incorporated with Union, and finally
Cylinder01 is incorporated with Subtraction.
Note: The operation for the first object in the
list has no effect on the Boolean object, but if
you move it to another position in the list it
does. You’ll see an example of this at the end of
this exercise.
You can use the list and the other controls i n
the Sub-object Operations group to change the
results.
8. In the list, highlight the Subtr - Cylinder01
entry, and then set Operation to Union.
9. In the Sub-object Operations group, click the
Change Operation button.
As a result of the change of operation, the
cylinder appears in the Boolean object as an
additive volume instead of a subtractive one.
Also, its entry in the list changes to “Union
- Cylinder01”, showing that the B oolean
operation for the cylinder is now Union.