9

674 Chapter 8: Modifiers
Note:
Repeat Last does not repe at all operations.
For example, it does not repeat transforms. To
determine which command will be repeated when
you click the button, check the button’s tooltip. If
no tooltip appears, nothing will happen when it is
clicked.
Constra ints—Lets you use existing geometry to
constrain sub-object transformation. Use the
drop-down list to choose the constraint type:
• None: No constraints.
• Edge: Constrains vertex transformations to
edge boundaries.
• Fa ce : Constrains vertex transformations to face
surfaces.
When set to Edge, moving a vertex will slide it along one
of the existing edges, depending on the direction of the
transformation. If set to Face, the vertex moves only on the
polygon’s surface.
Note: You can set constraints at the Object level, but
their use pertains primar i ly to sub-object levels.
The Constraints setting persists at a ll sub-object
levels.
Preserv e UVs —When on, you can edit sub-objects
without affecting the object’s UV mapping. You
can choose any of an object’s mapping channels
to preserve or not; see Preser ve UVs Settings,
following. D efault=off.
Without Preserve UVs, there is always a direct
correspondence b etween an object’s geometr y
and its UV mapping. For example, if you map an
objectandthenmovevertices,thetexturemoves
along with the sub-objects, whether you wa nt it
toornot.IfyouturnonPreserveUVs,youcan
perform minor editing tasks without changing
the mapping.
Tip: For best results with Preserve UVs at the
vertex level, use it for limited vertex editing. For
example, you’ll usually have no trouble moving
avertexwithinedgeorfaceconstraints. Also,
it’s better to perform one big move than several
smaller moves, a s multiple smal l moves can begin
to distort the mapping. If, however, you need
to perform extensive geometry editing while
preserving mapping, use the Channel Info utility
(page 2–1738) instead.
Original object (left); Scaled vertices with Preserve UVs off
(center); Scaled vertices with Preserve UVs on (right)
Pres er ve UV s S etti ngs—Opens the Preserve Map
Channels dialog (page 1–1075),whichletsyou
specify which ver tex color channels and/or texture
channels (map channels) to preserve. By default,
all vertex color channels are off (not preserved),
and a ll texture channels are on (preserved).
Cr e a te—Lets you create new geometr y. How this
button behaves depends on which level is active.
•
Object, Polygon, a nd El ement level s—Lets you
create polygons from isolated vert ices and
border vertices. All vertices in the object are
highlighted. Click three or more existing
vertices in succession to define the shape of the
new polygon. (The cursor changes to a cross
when it is over a vertex that can legally be part
of the polygon.) To finish polygon creation,
double-click the last vertex. You can also finish
creating the polygon by clicking any vertex
of the new polygon a second time. You can
also create new polygons at the Polygon and
Element sub-object levels.
Youcanaddverticesinthismodeby
Shi f t +clickinginanemptyspace;these