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1196 Chapter 9: Sur face Modeling
Ruled S urf rollout (m o d ificatio n time)
Flip Beginning and Flip End—Flip one of the curve
directions used to construct the ruled surface.
A ruled sur face is created using the direct ions
oftheparentcurves. Ifthetwoparentshave
opposing directions, the rule d surface can be
shaped like a bow tie. To correct the situation,
use F lip Beginning or Flip End to construct the
ruled surface using a direction opposite the
corresponding p arent cur ve’s direction. These
cont rols eliminate the need to reverse the curve.
Start Point 1 and Star t Point 2—Adjust the position
ofthestartpointatthetwocurvesthatspecify
the r uled surface. Adjusting the star t points can
help eliminate unwanted twists or "buckles" in the
surface.
Thesespinnersaredisablediftheedgesorcurves
are not closed.
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.
ReplaceFirstCurveandReplaceSecondCurve—Let
you replace the parent curves. Click a button,
then click the curve to replace the original first or
second curve.
Cap Surface
Select NURBS object. > Modify panel > Create Surfaces
rollout > Dependent Surfaces group box > Cap
Select N URBS obj ect. > Modify pane l > NURBS toolbox >
Create Cap Surface button
This command creates a surface that caps a closed
curve or the edge of a closed surface. Caps are
especially us eful with extrude d surfaces.
Capping an extrude surface
Procedure
To create a cap surface:
1.
InaNURBSobject,turnonCap.
2. Move the mouse over the closed curve or the
closed edge of a closed surface.
Ifthecapcanbecreated,thecurveoredgeis
highlighted in blue.
3. Click the highlighted curve or edge.
The Flip Normals control lets you flip the
surface normals at creation time. (After