2013

Spline
Uses the vertices of the selected polyline as the control points, or frame, of a
curve approximating a B-spline. This curve, called a spline-fit polyline, passes
through the first and last control points unless the original polyline was closed.
The curve is pulled toward the other points but does not necessarily pass
through them. The more control points you specify in a particular part of the
frame, the more pull they exert on the curve. Quadratic and cubic spline-fit
polylines can be generated.
Spline-fit polylines are very different from the curves produced by the Fit
option. Fit constructs pairs of arcs that pass through every control point. Both
of these curves are different from true B-splines produced with the
SPLINE
(page 1022) command.
If the original polyline included arc segments, they are straightened when the
spline's frame is formed. If the frame has width, the resulting spline tapers
smoothly from the width of the first vertex to the width of the last vertex. All
intermediate width information is ignored. Once spline-fit, the frame, if
displayed, is shown with zero width and CONTINUOUS linetype. Tangent
specifications on control point vertices have no effect on spline-fitting.
When a spline-fit curve is fit to a polyline, the spline-fit curve's frame is stored
so that it can be recalled by a subsequent decurving. You can turn a spline-fit
curve back into its frame polyline by using the PEDIT Decurve option. This
option works on fit curves in the same manner as it does on splines.
Most editing commands act the same when applied to spline-fit polylines or
fit curves.

MOVE (page 674), ERASE (page 410), COPY (page 235), MIRROR (page 650),
ROTATE (page 919), and SCALE (page 928) operate on both the spline curve
and its frame, whether the frame is visible or not.
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EXTEND (page 414) changes the frame by adding a new vertex where the
initial or final line of the frame intersects the boundary geometry.
P Commands | 785