9

Multisided Blend Surface 1213
Replace—
Lets you replace the selected curve.
Select a curve in the list, click this button, then
select the new curve.
Sweep Para llel—When off, the rail curves define
a ruled surface, and t he cross sections describe
lofting from this base ruled surface. When on,
each cross section is associated with its best
fittingplane. Thisplanemovesalongtherails
and parallel to them. If the r ails are curved, the
plane can rotate. If the spacing between the rai ls
changes, the section scales or stretches. In either
case, the surface is blended from section to section
along its entire length. Default=off.
Sweep Scale—Whenoff,thesizeoftheplaneis
scaled only in the direction across the rails. When
on, the plane is scaled uniformly in all directions.
Default=off.
Snap Cross-S ections—When on, cross-section
cur ves are t r anslated and scaled so they intersec t
both rails. The first cross sect ion is translated
to the start of the rails, and the last to the end of
therails. Thecrosssectionsinthemiddleare
translated to touch the rails at the closest point to
the ends of the cross-section c urves. Default=off.
When Snap Cross-Sections is on, the sweep
followstherailcurvesexactly.Thismakesiteasier
to construct 2-rail sweep surfaces.
Display Iso Curv es—When set, the 2-Rail Sweep’s
V-axis iso curves are displayed as well as the
U-axis curves used to construct the sweep. The
V-axis curves are only for display. You can’t use
them for surface construction.
Edit Curves—Lets you edit the currently selected
curve without switching to another sub-object
level. ClicktoturnonEditCurve. Thepoints
or CVs of the curve are displayed, as well as the
control lattice if the curve is a CV curve. You can
now transform or otherwise change the points
or CVs as if you were at the Point or Curve CV
sub-object level. To finish editing the curve, click
to turn off Edit Curves.
Tip: When you edit curves in a 2-rail sweep, turning
off display of the sweep itself can make the curves
easier to see and improve performance as well. Use
Ctrl +D (whi le the Keyboard Shortcut Override
Toggle (page 3–872) is on) to toggle display of
dependent sub-objects, including sweeps.
Thesweepsurfacecandeviatefromthecurve
if you edit a curve in a sweep by increasing the
weight of the curve CVs. You can work around
this by refining the curve at the point where the
surface deviates.
Multisided B lend Sur face
Select NURBS object. > Modify panel > Create Surfaces
rollout > Dependent Surfaces g roup box > N Blend
Select NURBS object. > Modify panel > NURBS toolbox >
Create a Multisided Blend Surface b utton
Multisided blend between three other sur faces
Amultisidedblendsurface"fillsin"theedges
defined by three or four other curve or surface
sub-objects. Un like a regular, two-sided blend
surface, the curves’ or surfaces’ edges must form a
closed loop; that is, they must completely surround
the opening that the multisided blend wil l cover.