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1190 Chapter 9: Sur face Modeling
and itsparentsurfaceatthesametime). You
transform it by transforming its gizmo. By using
transforms you can mirror about an arbitrary axis,
rather than using one of the Mir ror Axis presets.
When you transform a mirror surface, you are
actually transforming the mirror plane, so Rotate
has the effect of rotating the plane about which
the surface is mirrored. (This is like rotating the
mirror gizmo in the Mirror modifier.)
Tip: A convenient way to guarantee that a surface
is symmetr ica l is to c reate one side of t he surface,
mirror that surface, and then create a blend
between the two sides.
Offset—Controls the mirror’s distance from the
original surface. This parameter is animatable.
Replace Base Sur face—Lets you replace the parent
surface. Click the button, then click the new
surfaceonwhichtobasethemirror.
Ex trude Surfa ce
SelectNURBSobject.>Modifypanel>CreateSurfaces
rollout > Dependent Surfaces group box > Extrude
Select NU RB S object. > Modify panel > NURBS toolbox >
Create Extrude Surface button
An extrude surface is extruded from a curve
sub-object. It is similar to a surface created with
the Extrude modifier. The advantage is that an
extrude sub-object is part of the NURBS model, so
you can use it to construct other curve and surface
sub-objects.
Surface extruded from a curve
Procedure
To create an ex tr ude surface:
1.
In a NURBS object that contains at least
one curve, tur n on Ex t rude.
2. Movethecursoroverthecurvetoextrude,and
drag to set the ini
tial amount.
By default, the sur
face ext rudes along t he
NURBS model’s local Z axis. A gizmo (yellow
by default) indicates the direction of extr usion.
Transfor m ing t he
extrude surface’s gizmo
changes the direction of the extrude, letting you
extrude along an axis that isn’t aligned w ith a
local coordina
te axis.
The Flip Normal
s control lets you flip the
surface normals at creation time. (After
creation, you can flip normals using controls on
the Surface Co
mmon rollout.)
3. Adjust the ext
rusion parameters.
Interf ace
While an extrude sub-object is selected, a rollout
with the extrusion parameters is displayed at the
bottom of the
Modify panel.