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162 Chapter 5: Creating Geometry
Unify ing Normals
Use Unify Normals to make normals point in a
consistent direction. If an object has normals that
are inconsistent (some point outward and others
inward) the object will appear to have holes in its
surface.
Unify Normals is found on the Surface Properties
rollout and on the Normal modifier.
If you are animating the creation of a complex
object such as a nested Boolean or a loft, and you
think the operation might result in inconsistent
faces, apply a
Normal modifier (page 1–738) to the
result, and turn on Unify Normals.
Flipping Nor ma ls
UseFlipNormalstoreversethedirectionofall
selected faces. Flipping the norma ls of an object
turns it inside-out.
Flip Normals is found on the Surface Properties
rollout and on the Normal modifier.
The
Lathe modifier (page 1–699) sometimes
creates an object w ith normals pointing inward.
Use the Flip Normals check box on the Lathe
modifier’s Parameters rollout to adjust the
normals. You can a lso use the Normal modifier
w ith both Unify and Fl ip turned on to fix
inside-out lathed objects.
Viewi ng a nd Changi ng S moothing
Smoothingblendscolorsattheedgesbetween
faces to produce the appearance of a smooth
cur ved surface. You can control how smoothing
is applied to a surface so your objects can have
both smooth surfaces and sharp faceted edges at
theappropriateplaces.
The face labeled “1-2” shares smoothing groups with
adjacent faces, so the edges betwe en them are smoothed
over in renderings.
The face labeled “3” does not share a smo othing group, so
its e dge is visible in renderings.
Smoothing does not affect geometr y. It affects only
the way geometry is colored when rendered.
Smoothing is con trolled by smoothing groups,
which are numbered groups ranging from 1 to 32.
Each face is assigned to one or more smoothing
groups. When a scene is rendered, the renderer
checks each adjacent pair of faces to see if they
share a smoothing group, and renders the object
as follows:
• Iffaceshavenosmoothinggroupsincommon,
thefacesarerenderedwithasharpedge
between them.
• If faces have at least one smoothing group
incommon,theedgebetweenthefacesis
“smoothed”, meaning it is colored in such a
way that the area where the faces meet appears
smooth.
Becauseeachfacehasthreeedges,onlythree
smoothinggroupscanbeineffectforanyface.
Extra smoothing groups assigned to a face are
ignored.
Do one of the following to view or change
smoothing group assign ments: