Graphics Programs Reference
In-Depth Information
Splines and helixes
Splines are smooth linear objects, normally without corners that pass through or
near specified points. Spline is short for Nonuniform Rational B-Spline ( NURBS ).
Splines are described by a set of parametric mathematical equations, but have no
fear, for AutoCAD will internally deal with this, we will not have to!
Splines are used whenever we need smooth curves and are also the foundation for
NURBS surfaces, the most used surfaces in the automotive or aeronautic projects.
To create a spline we apply the (guess?) SPLINE command (alias SPL ). By default,
the command only prompts for the location of fit points, and the spline passes
through the specified points. An Enter finishes the spline and the Close option cre-
ates a closed spline.
We can control splines by two sets of vertices:
Fit points : These are the points used to create the spline
Control vertices : These are the points that define the spline
When selected, the small blue triangle allows switching between Fit points and
Control vertices . To edit a spline is very simple: we select it, without command,
and work with grips. We can either click a grip and move it, or we can place the curs-
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