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SPLINEDIT (Command)

Product Documentation
Intermediate
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Modifies the parameters of a spline or converts a spline-fit polyline to a spline.

Summary

Modifies the data that defines a spline, such as the number and weight of control vertices, the fit tolerance, and the starting and ending tangents.

Note SPLINEDIT automatically converts spline-fit polylines to splines even if you immediately exit SPLINEDIT after selecting the spline-fit polyline.

The data that defines a spline is represented in one of two formats: as a control frame or as fit points. The format can change depending on how the spline was orginally created, the options selected from the grip menus, or the options used in SPLINEDIT.

You can change any of following data:

  • Control frame data consists of control vertices, the polynomial degree of the spline, and the weights assigned to each control vertex.
  • Fit data consists of fit points, knot parameterization, the fit tolerance, and the tangents at the endpoints of the spline.
Note Switching from displaying control vertices to fit points automatically changes the selected spline to degree 3. Splines originally created using higher-degree equations will likely change shape as a result. In addition, if the spline was created using a positive tolerance value, the fit points will be relocated to the knots on the spline, and the tolerance value is reset to 0.

List of Prompts

The following prompts are displayed.

Select spline

Specifies which spine you want to modify.

Close/Open

One of the following options displays, depending on whether the selected spline is open or closed. An open spline has two endpoints, while a closed spline forms a loop.

Close

Closes an open spline by defining the last point to be coincident with the first. By default, closed splines are periodic, maintaining curvature continuity (C2) along the entire curve.

Open

Opens a closed spline by removing the final curve segment between the first and last points specified when the spline was originally created.

Join

Combines a selected spline with other splines, lines, polylines, and arcs at coincident endpoints to form a larger spline. Objects are joined with kinks at the points where they are joined (C0 continuity).

Fit Data

Edits fit point data using the following options:

Add
Adds fit points to the spline.

After selecting a fit point, specify a new fit point to be added to the spline in the direction of the next fit point, which is automatically highlighted.

If you select the last fit point on an open spline, the new fit point is added to the end of the spline.

If you select the first fit point on an open spline, you have the option of specifying whether the new fit point is added before or after the first point.

Close/Open
One of the following options displays, depending on whether the selected spline is open or closed. An open spline has two endpoints, while a closed spline forms a loop.
  • Close. Closes an open spline by defining the last point to be coincident with the first. By default, closed splines are periodic, maintaining curvature continuity (C2) along the entire curve.
  • Open. Opens a closed spline by removing the final curve segment between the first and last points specified when the spline was originally created.
Delete
Removes selected fit points from a spline.
Kink
Adds a knot and fit point at the specified location on the spline, which does not maintain tangent or curvature continuity at that point.
Move
Moves fit points to new locations.
  • New Location. Moves the selected fit point to the specified location.
  • Next. Specifies the next fit point.
  • Previous. Specifies the previous fit point.
  • Select point. Specifies any fit point on the spline.
Purge
Replaces the fit data from the spline with control vertices.
Tangents
Changes the starting and ending tangents of a spline. Specify a point to establish a tangent direction. You can use object snaps such as Perpendicular or Parallel.
  • Specify tangent. (Available for closed splines) Specifies a new tangent direction at the point of closure.
  • System default. Calculates the default end tangents.
Tolerance

Refits the spline to the existing fit points using the new tolerance value.

Exit
Returns to the previous prompt.

Edit Vertex

Edits control frame data using the following options:

Add
Adds a new control vertex at the point you specify that is located between two existing control vertices.
Delete
Removes a selected control vertex.
Elevate Order
Increases the polynomial order (degree plus one) of the spline. This results in increasing the number of control vertices across the spline.

The maximum value is 26.

Move

Relocates a selected control vertex.

  • New Location
  • Next
  • Previous
  • Select Point
Weight
Changes the weight of a specified control vertex.
  • New weight. Recalculates the spline based on the new weight value for the specified control vertex. A larger value pulls the spline closer to the control vertex.
Exit
Returns to the previous prompt.

Convert to Polyline

Converts the spline to a polyline.

The precision value determines how closely the resulting polyline matches the spline. Valid values are any integer between 0 and 99.

Note A high precision value will decrease performance.

The PLINECONVERTMODE system variable determines whether the polylines are created with linear or arc segments.

The DELOBJ system variable determines whether the original spline is retained.

Reverse

Reverses the direction of the spline. This option is intended primarily for third-party applications.

Undo

Cancels the last action.

Exit

Ends the command.

Related References

Related Concepts

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