9

2-Rail Sweep Surface 1211
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 dow n adjustment. When you release
the mouse button, the surf ace reappears.
Insert—(Disabled.)
Remove—Removes a curve from the list. Select the
curve in the list, and the n click Remove.
Refine—(Disabled.)
Replace—(Disabled.)
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
the rails. The cross sections in the middle are
translated to touch the rails at the closest point to
the ends of the cross-sect ion curves. D efault=off.
When Snap Cross-Sections is on, the sweep
follows the rail curves exactly. This makes it easier
to construct 2-rail sweep surfaces.
Display While Creating—When on, the sweep
surfaceisdisplayedwhileyoucreateit. When
off,thesweepcanbecreatedmorequickly.
Default=off.
Flip Normals—Reverses the direction of the sweep’s
normals.