9

CV Curve on Surface 1173
create a curve on a surface if the portion of the
surfacewherethecurvewilllieisclearlyvisiblein
the viewport. However, this method doesn’t let
you place CVs on surface locations that are not
visible in the viewport (they are on back faces, lie
behind other geometr y, and so on).
Using the Edit Cur ve on S ur face Dia log
The Edit Cur ve on Surface dialog (page 1–1229)
letsyoueditcurvesonsurfacesasyoueditregular
curvesinaviewport.Themainpartofthedialog
is a two-dimensional view of the surface. The
controlsprovidetypicalcurveeditingfunctions.
WhileyouarecreatingaCVcurveonsurface,the
2D View toggle controls display of the Edit Curve
on Surface dialog.
You can edit the CVs in CV curves on surfaces at
the Curve CV sub-object level (page 1–1127),asyou
edit other kinds of curve CVs. You can transform
CVsinCVcurvesonsurfaces,butyoucan’tmove
the CVs off the su rface. Using the Curve CV
sub-object level is an alternative to editing these
CVs by using the Edit Curve on Surface dialog.
Procedure
To crea te a CV cur v e on surf ace:
1.
In a NURBS object that contains at least
onesurface,turnonCreateCVCurveon
Surface in the NURBS toolbox, or CV on Surf
ontheCreateCurvesrollout.
2. Do one of the following:
• Draw the curve in t he viewport, using the
mouseabovethesurface.
• Turn on 2D View. This displays an Edit
Curve on Surface dialog, which lets you
create the curve in a two-dimensional (UV)
representation of the surface.
3. Right-click to end curve creation.
Interfa ce
CV Curve on Surface rollout (creation time)
Trim Controls grou p
Tri m—When on, trims the surface against the
curve. When off, the surface isn’t trimmed.
If it’s impossible to trim with this curve, the surface
is displayed in the error color (orange by default).
For example, the curve is unusable for trimming if
it doesn’t form a closed loop.
Flip Trim—When on, t rims the surface in the
opposite direction.
Automatic Reparam e ter ization group
The radio buttons in this group box let you
choose automatic reparameterization. With
reparameterization, the curve maintains its
parameterization as you edit it. Without
reparameterization, the curve’s parameterization
doesn’t change as you edit it, and can become
irregular.
None—Do not reparameterize.
Chord L e n g t h —Cho o ses the chord-length
algorithm for reparameterization.
Chord-length reparameterization spaces knots (in
parameter space (page 3–988)) based on the square
rootofthelengthofeachcurvesegment.