8

2-Rail Sweep Surface 1211
endpoints of the first c ross-section curve must be
coincident. U se NURBS Snaps to accomplish this.
Automatic Cur ve Att achment
When you create a 2-rail sweep, you can select
curves that are not a lready sub-objects of the ac tive
NURBS model. You can select another curve or
spline object (page 1–261) in the scene. When you
select that cu rve, it attaches to the current object as
if you had used the
Attach button (page 1–1121) .
Wa rni ng: If the curve you attach is a sub-object of
anotherNURBSmodel,theentiremodel(thatis,the
curve’sparentNURBSobject)isattachedaswell.
Asyoumovethemouseoveracurvethatisnot
part of the active NURBS object, the cursor
changes shape to indicate that you can pick the
cur ve, but the curve is not highlig hted in blue.
Pr ocedur es
To create a 2 -ra il sweep:
1.
Create the curves that define the surface you
want to create.
2. Clicktoturnon2RailSweepinthe
toolbo x or on the Create Surfaces rollout.
3. Clickthecurvetouseasthefirstrail,thenclick
the curve to use a s the second rail. C lick each of
the cross-section curves, and then r ight-click to
end creation.
The sweep is interpolated smo othly b etween
the cross sections, follow ing the outlines
defined by the two rails.
As you click curves, their names appear in
the lists on the 2 Rail Sweep Surface creation
rollout. The order in which you click the curves
can affect the shape of the sweep surface.
Ex ample: To create a 2-ra il sweep wi th a utoma tic
attach:
1.
From the Create panel, create three independent
CV or Point NURBS curves.
2. Go to the Modify p anel, and click to turn on
2-Rail Sweep in the NU RBS toolbox.
3. Select the curves in the appropriate order for
the sweep.
The s weep is created. You don’t need to collapse
the curves to a NURBS surface or Attach them
to an existing NURBS model.
Asyoumovethemouseoveracurvethatisnot
partoftheactiveNURBSobject,thecursor
changes shape to indicate that you can pick the
cur ve, but the curve is not highlig hted in blue.
Interf ace
While a 2-rail sweep sub-object is selected, a
rollout with the 2-rail sweep p arameters appears.
This rollout appears only and when
one 2-rail
sweep sub-object is selected. It isn’t possible
to edit more than one 2-rail sweep at a time,
so unlike some other NURBS sub-objects, the
rollout doesn’t appear when multiple 2-rail sweep
sub-objects are selected.
Tip: When you edit a 2-rail sweep sub-object,
closetheSurfaceCommonrollouttoseethe2-rail
sweep surface rollout more easily.