9

508 Chapter 8: Modifiers
To transform a sub-object selection made with a
Select modifier:
1.
Add an XForm modifier (page 1–959) to the
stack, following (or somewhere above) the
Select modifier.
2. In the stack, open the Select modifier and make
a sub-object selection.
3. Choose XForm in the stack. You then transform
the XForm gizmo, wh ich applies the transform
to the selection.
Selecting and Tr ansforming Modif ier
Components
Most modifiers have sub-object components,
such as a gizmo and center. Like sub-object
geometry, these componen ts can be accessed
and tr ansformed at sub-object level, directly
modifying the object’s shape.
Other modifiers, like those for free-form
deformation, have control points and lattices at a
sub-object level. Moving these components creates
the modeling effects of the modifier.
Usin g the S tack at t he S ub-Object
Level
Witheditableobjectssuchasmeshesandsplines,
or modifiers w ith sub-object levels such as Mesh
Select and Spline Select, you can continue to model
a single sub-object selection by applying any
number of other modifiers. When you go back and
change the original selection, the new selection is
"passed up the st ack" to the modifiers that follow.
Editable meshes and splines have "built-in"
sub-object select ion at their base level. But the
selections you mak e with Mesh Select and Spline
Selectworkexactlythesamewayonthestack.
Thistopicusesmeshesforitsexamples. You
canapplythesameconceptstoeditablesplines,
patches, and poly objects.
Working a t Two Levels
When you select an object and apply modifiers
(for example, Bend and Taper), you’re working
with the object as a single unit, or "whole object",
at the object level.
Whenyoumakeasub-objectselection,thestack
display changes to show you are no longer working
with the whole object. Consider the effect of a
Mesh Select applied between Bend and Taper
modifiers (B en d is below Taper). To the right of
the Mesh Select and Taper modifiers, a sub-object
icon (similar to the sub-object button in the
Selection rollout) appears to show that sub-object
selection is now in effect.
The vertex sub-object select ion made at the Mesh
Select level is passed up the stack to the Taper
modifier. This means the Taper modifier is applied
only to the vertices selected at the Mesh S elect
level.
Sub-object icon (in this case, for Vertex) to the right of modifier
names in the stack display
Sub-object selection carries upward through the
stack. If you add more modifiers, each shows the
sub-object icon to indicat e this state.
By learning to "read the stack," you can move back
and forth b e tween the object and sub-object levels
while you work on an object.
Returning to Whole-O bject Level
When you finish modeling a cert ain sub-object
selection, you can return to work on the whole
object.