9.5.2

OBJECTS MENU • SPLINES • 245
Splines
Spline Object
This command creates an empty spline object. Like the Polygon object, it is recognizable on screen
only by its origin and axes. You can use this object for the construction of your own splines.
Curves
Splines are primarily a sequence of vertices, connected by lines, lying in 3D space. The shape of these
connecting lines (straight or curved) denes the interpolation. Apart from the direct connection of
the vertices with straight, rigid lines, there are other kinds of splines that use an interpolation method
where the lines between the vertices are curved instead of straight. These splines have a soft leading
edge without sharp corners.
The spline itself is innitely thin. A spline is not visible when rendered. The spline’s line has no three-
dimensional depth, even though it occupies the 3D space. However, many complex 3D objects, among
other things, can be constructed in seconds out of these curves by using them with NURBS objects.
After the spline is created it can be pulled along its depth in order to make tube-like objects. You
can also rotate a spline around an axis to create objects that have rotational symmetry, such as
wineglasses. Or you can construct a skin over several splines, with the nished object simulating the
contours on a map. More of these spline-modeling capabilities are discussed in the NURBS section.
To create a new spline curve:
 Choose Objects > Spline Object to create an empty spline.
 Select the Points tool (click the Points icon or choose Tools > Points) and
select the Move tool (choose Tools > Move).
 Create points for the spline by Ctrl-clicking in each place where you want to
create a point. The rst point denes the start of the spline.
 If you Ctrl-click on the curve between two existing points, the new point will
be placed on the spline between the points.
 If you hold down the Shift and Ctrl keys while clicking, the new point will be
created at the beginning of the spline, giving a new starting point.
 If the Close Spline option is enabled and you Ctrl-click the starting point,
the spline will be closed.
 You can move points by dragging and dropping them. To select multiple
points, Shift-click each point (or use a selection tool).