8

How to Make Objects with NURBS M odeling 1097
• There are special NURBS Snaps in the Grid and
Snap Settings dialog (page 2–38)
(rig ht-click
the 3D Snap toggle to display this). When
you use NURBS snaps, turn off Options/Axis
Constraints; otherwise, snaps work only in the
current axis.
Also, remember that snaps work in a viewport
onlywhenyouhavemadetheviewportactive.
And choosing your snap sett ings does
not turn
onsnaps.Youmustalsoturnonthe
3D Snap
Togg le button (page 2–35)
(on the st atus bar).
Snaps are especially important when you create
the curves for building
1-rail (p age 1–1205)
and 2-rail (page 1–1210) sweep surfaces.
• Remember that without leaving the viewport ,
you can right-click to display a
quad menu
(page 3–741)
with shortcuts for chang i ng the
sub-object level, creating some sub-objects,
and using some other edit commands.
•WhenyouworkwithNURBS,therearealot
of rollouts in the Modify panel. Minimize
the rollouts you don’ t need. For example,
minimizing the Modifiers rollout helps unless
you’re applying Modifiers, and minimizing the
Surface Common rollout is useful when you’re
creating U loft, UV loft, and 1-rail or 2-rail
sweep surfaces.
• Don’t set view p orts to display edged faces.
Displaying edges is almost twice as slow as
displaying a simple shaded view p ort.
Cr e at in g Curves
• When drawing a CV cur ve, click three times
to get a sharp corner.
Be aware, however, that multiple CVs increase
the amount of calculation and therefore reduce
the per formance and stabilit y of your model.
However , if you want to use the curve to
construct a U Loft, and so on, this is the best
technique.
• Youcanalsocreatesharpcornersbyfusingthe
ends of two separate N URBS curve sub-objec ts.
This is the recommended method if you aren’t
using the curves to construct a surface.
• Whilecreatingcurves,youcanturnonthe
Draw in All Viewports toggle. This lets you
draw curves in 3D. Beg in drawing a curve in
one viewport, go to another viewport, and
continue drawing.
Ifyourmousehasamiddlemousebutton,
ALT+middle mouse button lets you use
arc
rotate (page 3–787)
to change a viewport’s
orientation while you are creating the curve.
• To create a transform curve along a specific
axis,turnontheappropriateaxisconstraints,
and then SHIFT+move a copy of the transform
curve.
Curves an d D irection
• NURBS curves show their direction in
viewports. A small c ircle indicates the first
vertex. If the curve is closed, a plus sign (+)
indicates the direction of the curve.
Beawareofcurvedirectionwhenyouuse
curves to construct
blend surfaces (page
1–1184)
, U loft (page 1–1197) and UV loft
(page 1–1202)
surfaces, and 1-rail (p age
1–1205)
and 2-rail (page 1–1210) sweeps. If
the curves don’t have the same direction, you
can get strange twisting . Make sure curves
have the same direction before you construct
thesurface. OntheCurveCommonrollout,
the cont rols Reverse and Make First let you
control the direction of the curve, and where its
starting point or CV is located.
Another good way to make sure curves are
aligned is to draw one curve and then use
SHIFT+Clonetocreatetheothers. After
creat ing the aligned curves, you can transform
CVs to vary the curves on which the surface
will be based.