9

166 Chapter 5: Creating Geometry
Clo se—Exits the Clipboard utility.
Adj usti ng Nor ma ls a nd
S moothi ng
In general, you adjust normals and smoothing to
prepare objects for rendering.
A nor mal (page 3–980) is a unit vector that defines
which way a face or vertex is pointing. The
directioninwhichthenormalpointsrepresents
thefront,oroutersurfaceofthefaceorvertex,
which is the side of the surface that is norm ally
displayed and rendered.
You can manually flip or unify face normals to fix
surfaceerrorscausedbymodelingoperationsor
byimportingmeshesfromotherprograms.
Smoothing groups define whether a surface is
rendered with sharp edges or smooth surfaces.
Smoothinggroupsarenumbersassignedtothe
faces of an object. Each face can carry any number
of smoothing g roups up to the maximum of 32.
If two faces share an edge and share the same
smoothing group, they render as a smooth su rface.
Iftheydon’tsharethesamesmoothinggroup,the
edge b etween t hem renders as a corner. You can
manually change or animate smoothing group
assignment. Changing smoothing groups does not
alter geometry in any way; it only changes the way
facesandedgesareshaded.
See also
Viewing and Changing Normals (page 1–166)
Viewing and Changing Smoothing (page 1–167)
Viewing and Changing Nor mals
When you create an object, nor m als (page 3–980)
are generated automatically. Usually objects render
correctly using t hese default norm als. Sometimes,
however, you need to adjust the normals.
Left: The normals shown as spikes indicate the orientation of
faces on the pyramid.
Right : Flipping normals can make faces invisible (or visible) in
shaded viewports and renderings.
Undesired normals can appear in these objects:
• Meshes imported from other applications.
• Geometry genera ted by complex operations
such as Boolean objects, lathe objects, or lofts.
Norm als are used to define which side of a face or
vertex is considered the "out" side. The out side of
a face or vertex is t he side that gets rendered un less
you are using t wo-sided materials, or turn on the
Force2-SidedoptionintheRenderScenedialog
>Commonpanel>Common P arameters rollout
(page 3–27).
Do one of the following to view or change face
normals: