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1214 Chapter 9: Sur face Modeling
andthenusethearrowstomovetheselectionup
or down.
Curve Properties group
These cont rols affect individual cur ves you select
in the S ec tion Curves list, as opposed to properties
of the sweep surface in general. They are enabled
only when you have selected a curve in the Section
Curves list.
Reverse—When set, reverses the direction of the
selected curve.
Start Point—Adjusts the position of the curve’s
start point. This can help eliminate unwanted
tw ists or "buckles" in the surface.
Thiscontrolisdisabledifthecurveisnotaclosed
cur ve.
While you’re adjusting start points, a dotted
blue line is displayed between them, to show the
alignment. The surface is not displayed, so it
doesn’t slow down adjustment. When you release
the mouse button, the su rface reappears.
Insert—Adds a curve to the section list. Click to
turn on Insert, then click the curve. The curve
is inserted
before the selected curve. To insert a
cur ve at the end, first hig hlight the "----End-----"
marker in the l ist.
Remove—Removes a curve from the list. Select the
curve in t he list, and then click Remove.
Refine—Refines the 2-rail sweep sur face. Click
to turn on Refine, then click an iso curve on the
surface. (As you drag the mouse over the surfa ce,
the available sect ion curves are highlighted.) The
curve you click is converted to a CV curve and
inserted into the sweep and the section list. As
when you refine a point curve, refining a sweep
can change the curvature of t he surface slightly.
Once you’ve refined the surface by adding a
cross-section c urve, you can use Edit Curves to
change the curve.
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 the cross sections describe
lofting f rom this base ruled surface. When on,
each cross sect ion is associated with its best
fittingplane. Thisplanemovesalongtherails
and par allel to them. If the r ai ls are curved, the
plane can rotate. If the spacing between the rails
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 translated and scaled so they intersect
both rails. The first cross section is t ranslated
tothestartoftherails,andthelasttotheendof
the rails. The cross sections in the middle are
translated to touch the rails at the closest point to
the ends of the cross-section curves. Default=off.
When Snap Cross-Sections is on, the sweep
follows the r ai l curves exactly. This ma kes it easier
to construct 2-rail sweep surfaces.
Display Is o Cur ves—When set, the 2-Rail Sweep’s
V-axisisocurvesaredisplayedaswellasthe
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 Cur ves—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