9

CV Curve 1111
CVs sh ape the control lattice that defines the curve.
Dra wing T hree-Dimensi onal Cur ves
WhenyoucreateaCVcurve,youcandrawitin
threedimensions.Therearetwowaystodothis:
• Draw In All Viewports: T hi s toggle lets you use
any v iewport to draw the curve, enabling you
to draw three dimensionally.
•Using
Ct rl to dr ag CVs: While you draw a
cur ve, you can use the
Ctrl key to drag a CV
offoftheconstructionplane.
With the
Ct rl –key metho d, further mouse
movement lif t s the latest CV off the construction
plane.Therearetwowaystousethis:
•Click-drag.Ifyouholddown
Ct rl and a ls o
hold down the mouse button, you can drag to
change the height of the CV. The CV’s location
is set when you release the mouse button.
This method is probably more intuitive.
• Click-click. If you
Ct rl +click and then release
the mouse button, the height changes as you
drag the mouse. Clicking the mouse a second
time sets the CV’s location.
This metho d is less prone to repetitive stress
injury.
WhileyouareoffsettingtheCV,areddotted
line is drawn between the original C V on the
construction plane and the actual CV offset
fromtheplane.Youcanmovethemouseintoan
inactive viewport, in which case the software sets
the height of the CV using the CV’s Z axis in the
inactive viewport. This lets you set the heig ht of
the CV with accurac y.
Snaps (page 2–41) also work w hen you change the
height of a CV. For example, if you turn on CV
snapping, you can set a CV to have the same height
as another CV by snapping to that other CV in an
inactive viewport.
Procedure
To cr eate a NUR B S CV cur ve:
1.
Go to the Create panel.
2. Turn on Shapes, and choose NURBS
Curves from the drop-down list.
3. Tu r n on C V Cu r ve.
4. In a viewport, click and drag to create the
first CV, as well as the first curve segment.
ReleasethemousetoaddthesecondCV.Each
subsequent location you click adds a new CV to
the curve. Right-click to end curve creation.
Note: If you begin the curve by clicki ng without
dragging, this also creates the curve’s first CV.
However, if you release the mouse more than
five pixels away from where you initially pressed
it, this creates an additional CV.
While you are creating a CV curve, you can
press
Backspace to remove the last CV you
created, and then previous CVs in reverse order .
If Draw In All Viewports is on, you can draw in
any viewpor t, creating a 3D curve.
To lif t a CV off the construction plane, use
the
Ctrl key as described earlier in this topic
under "Drawing T hree-Dimensional Curves."
As with splines, if you click over the curve’s
initial CV, a Close Curve dialog (page 1–1228)
is displayed. This dialog asks whether you