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CV Sub-Objects and Point Sub-Objects 1085
between various levels of the NURBS model:
Top Level, Surface CV Level, Surface Level,
Curve CV Level, Point Level, Curve Level, and
Imports Level.
• The command panel’s right-click popup menu
(available whenever the mouse curs or becomes
a pan hand) helps you navigate the rollouts on
the current command panel.
If you have a three-button or wheel mouse,
rolling the wheel scrolls the command panel.
• Sub-object selection sets are p ersistent. If you
go to a different sub-object level, when you
return to the previous level, your selection is
still available. However, refining or inserting
points or CVs ma kes the sub-object selection
sets invalid for that object.
• You can move a sub-object selection set among
sub-objects at the active level of the NURBS
model by holding down
Ctrl while you press
the arrow keys.
• When you select surface CV sub-objects that are
"on top of " e ach other in a 3D view, sometimes
all the selected CVs fail to highlight. To fix this,
choose Customize > Viewport Configuration
(page 3–853),andturnonZ-bufferWireframe
Objects.
CV Sub-Objects and Point
Sub-Objects
Independent curves and independent surfaces
both come in two varieties: they are either CV
sub-objects or point sub-objects. This topic
describes the differences b etween the two.
CV Curve s a nd CV Su rfa ces
CV curves and CV surfaces have control vertices
(CVs)asdosplines. ThepositionoftheCVs
controls the shape of the curve or the surface.
However, unlike spline vertices, CVs don’t
necessarilylieonthecurveorsurfacetheydefine.
The CVs define a control lattice (page 3–923) that
connects the CVs and surrounds the N URBS
curve or surface. The control lattice displays in
lines that are yellow by default.
Cone-shaped NURBS sur face with i ts control lattice (CVs are
displayed as green squares)
Tip: When you use Zoom Extents, the entire extents
of a NURBS object are displayed, including its
control lattice. Because CVs can be located some
distance from an object, the curve or sur face itself
(the object’s renderable geometry) is sometimes
hard to see. If this happens, use Zoom Region or
Field of View to zoom in.
YoucanmoveaCVattheCurveCVorSurface
CV sub-object level on the Modif y panel. Other
transforms, rotate and scale, work as wel l. Rotate
and scale are useful m ain ly when you have selected
multiple CVs.