9

1106 Chapter 9: Surface Modeling
NURBS Cur ve Primitives
Create panel > Shapes button > N URBS Curves
NURBS (page 3–980) curves are Shape objects
(page 1–262),andyoucanusethemasyou
dosplines. YoucanusetheExtrudeorLathe
modifiers to generate a 3D surface base d on a
NURBS curve. You can use NURBS curves as
thepathortheshapeofaloft. (Loftscreated
using NURBS curves are loft objects, not NURBS
objects.)
You can also use NURBS cur ves as Path Constraint
and Pat h Deform paths or as motion t r ajectories.
You can assign thickness to a NU RBS curve so it
rendersasacylindricalobject. (Thethickened
curve renders as a polygonal mesh, not as a
NURBS surface.)
Acurveandthesamecurverenderedwiththickness
There are two kinds of NURBS cur ve objects:
Point Cur ve (page 1–1106)
CV Curve (page 1–1110)
Like other Shape objects, NURBS curves can
contain multiple sub-objects, which are either
dependent or independent.
Creating Curve Sub-Objects (page 1–1151)
Creating Surface Sub-Objects (page 1–1177)
Cr eating and Editing Point Sub-Objects (page
1–1219)
Common Sub-Object Controls (page 1–1122)
Editing Point Sub-Objects (page 1–1123)
Editing Curve CV Sub-Objects (page 1–1127)
Editing Surface CV Sub-Objects (page 1–1130)
Editing Curve Sub-Objects (page 1–1135)
Editing Surface Sub-Objects (page 1–1141)
Note: Like an object-level NU RBS surface (page
1–1101), an object-level NURBS curve is a
top-level NURBS model (page 3–980) that can
contain NURBS cur ve, NURBS surface, and
NURBS p oint sub-objects. A NURBS cur ve
remainsaShapeobjectunlessyouaddasurface
sub-objecttoit;ifyoudo,itconvertstoaNURBS
surface (without changing its name).
Creating Independent Surfaces from NURBS Curve
Objects (page 1–1114)
Yo u c a n a l s o c r e a t e N U R B S c u r v e s u b - o b j e c t s b y
attachingorimportingotherobjectssuchasother
NURBS curves or spline shapes.
Attaching and I mporting 3ds Max Objects (page
1–1120)
Display Controls for N UR BS Models (page 1–1117)
Both NURBS curves and NURBS surfaces have a
DisplayareaintheModifypanel.Thesecontrols
affect which portions of the NURBS geometry are
displayed. Next to the Display area is the button
that turns on the toolbox for creating sub-objects.
Poi nt Curve
Create panel > Shapes bu tton > NURBS Curves > Point
Curve button
Createmenu>NURBS>PointCurve
Point curves are NURBS cur ves (page 1–1106)
whose points are constrained to lie on the curve.
ApointcurvecanbethebasisofafullNURBS
model (page 3–980).