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786 Chapter 8: Modifiers
outward. If an object has no faces with at least one
free edge, Shell will not create any edges.
Ex a mpl es of Shel l Us a ge
Following are some examples of modeling tasks
forwhichtheShellmodifierwouldbeappropriate:
• Anartistismodelingavehiclesuchasacar,a
tank,or,inthiscase,ahelicopter.Theartist
builds a solid external shell as the body of the
copter. When done, the modeler breaks up his
model: he selects window areas and detaches
them as new objects, followed by the area for
the doors (a lso detached as new objects). The
modeler now has open objects representing
the body, w indows, and doors. The modeler
applies Shell to the body, and sets it to extrude
both outward and inward a set number of units,
setting the inward extr usion to be greater than
the outward. Shell is applied to the windows
next; these are set to extrude inward only. The
modeler t hen copies the Shell modifier from
the body to the doors, and reduces the doors’
outward extrusion somewhat. The result is
a solid body with an in terior that can accept
additional modeling, inset windows, and doors
that are slig htly less thick than the shell of the
helicopter.
• A designer is modeling a manufactured object
thatwillneedtobeshowninanexploded
view. It might be a cell phone, an engine, a
mouse, shaped glass, or something similar;
this example will use part of a cell phone.
When working on the phone keypad area, if the
modeler builds with detail in mind, she might
accurately model the shell with a moderately
dense mesh, using ShapeMerge (page 1–336)
to create the shapes for the holes where the
keys will poke through, and then deleting those
faces. When satisfied, the modeler applies the
Shell modifier, sets Segments to 2, and then
turns on the Bevel Edges option to use a curve
for the profile of the holes’ edges. She then
applies a MeshSmooth modifier on top. The
extra segment helps control the curve of the
edges where the outer surface curves down to
the keypad holes. The modeler then goes b ack
to the cage portion of the stack and refines the
base mesh details to her liking.
• A modeler is creating a suit of futuristic armor
for a character. The modeler copies a selection
of polygons from the character mesh to a new
object; for example, the polygons that make up
the arm. The modeler deletes some faces from
the copied arm, and perhaps cuts some holes
fromit. HethenappliestheShellmodifier,
followed by a MeshSmooth modi fier, result ing
in form-fitting armor.
Procedure
To solidify a n object:
1.
Create an object to solidify. The object should
have some holes in its surface. For example,
start with a primitive sphere, conv ert it to
Editable Poly, and delete some vertices or
polygons.
2. Opt ionally create an open spline to serve as
theprofilefortheedgesconnectingtheinner
and outer surfaces. For example, go to Create
panel > Shapes and click Line. Then, in the
Top v i e w p o r t , d r a w t h e s p l i n e i n t h e Top
viewport from top to bottom. Where the spline
protrudes to the right, the edge surface w ill be
convex, and where it protrudes to the left, the
surface will be concave.
3. Apply the Shell modifier to the object from step
1.
4. To use custom edges, turn on Bevel Edges, click
the Bevel Spline button, and then selec t the
spline from step 2.
5. By default, Shell keeps the material IDs of
the new surfaces consistent with those of the
original object. To change these, turn on the
different Override options, specify appropriate