Drawing Curves - Mastering AutoCAD for Mac - page 471

points, and you can adjust the curve by clicking the grip points and moving them. You'll also
see an arrowhead grip that appears at the beginning of the spline. If you click this arrowhead
grip, you see two options: Show Fit Points and Show Control Vertices (Figure 17.21).
FIGURE 17.21
The Show Fit
Points and Show
Control Vertices
options
Click the arrowhead to
open the list of options.
The Show Fit Points option will display the grips at the fit points, which are the points you used
to draw the spline in the previous example. By default, these fit points lie on the spline, though you
can adjust how close the spline follows the fit points. You can also view the control vertices, or CVs
for short, which are points that control the curvature of the spline and do not lie on the spline itself
(refer back to Figure 17.17). Along with the control vertices, you see a set of vectors called the control
polyline . The control polyline helps you visualize the relationship between the CVs and the spline.
If you hover over a grip, you will see a menu that offers Stretch Fit Point, Add Fit Point, and
Remove Fit Point. Stretch Fit Point enables you stretch the highlighted grip. Remove Fit Point
will remove the grip. If you select Add Fit Point, you can click a point to indicate a new fit point
to be added to the spline.
Understanding the Spline Options
You may have noticed a few other options in the first Spline command prompt. When you start
the Spline command, you see the Method, Knots, Degree, and Object options:
Method Method lets you choose between Fit and CV. The Fit option causes the spline to be
drawn through the lines you select. The CV, or Control Vertices, option causes the spline to
use your selected points as control vertices (refer back to Figure 17.17). Once you've drawn a
spline, you can switch between fit and CV views of your polyline (Figure 17.21).
Knots This option is available only if Fit is chosen in the Method option discussed previ-
ously. This option offers three additional options: Chord, Square Root, and Uniform, which
affect the shape of the spline as it passes through the it point.
Chord The Chord option numbers the knots with decimal values.