Edit Splines

AutoCAD ActiveX

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Create and Edit AutoCAD Entities > Edit Objects >

Edit Splines

Use the following editable properties to change splines:

ControlPoints: Specifies the control points of a spline.
EndTangent: Specifies the end tangent of the spline as a directional vector.
FitPoints: Specifies all the fit points of a spline.
FitTolerance: Refits the spline to the existing points with new tolerance values.
Knots: Specifies the knots vector for the spline.
StartTangent: Specifies the start tangent for the spline.

In addition, you can use the following methods to edit splines:

AddFitPoint: Adds a single fit point to the spline at a given index.
DeleteFitPoint: Deletes the fit point of a spline at a given index.
ElevateOrder: Elevates the order of the spline to the given order.
GetFitPoint: Gets the fit point of the spline at a given index. (Gets one fit point only. To query all the fit points of the spline, use the FitPoints property.)
Reverse: Reverses the direction of a spline.
SetControlPoint: Sets the control point of the spline at a given index.
SetFitPoint: Sets the fit point of the spline at a given index. (Sets one fit point only. To change all the fit points of the spline, use the FitPoints property.)
SetWeight: Sets the weight of the control point at a given index.

Use the following read-only properties to query splines:

Area: Gets the enclosed area of a spline.
Closed: Indicates whether the spline is open or closed.
Degree: Gets the degree of the spline's polynomial representation.
IsPeriodic: Specifies if the given spline is periodic.
IsPlanar: Specifies if the given spline is planar.
IsRational: Specifies if the given spline is rational.
NumberOfControlPoints: Gets the number of control points of the spline.
NumberOfFitPoints: Gets the number of fit points of the spline.

For more information about editing splines, see “Modify Splines” in the User's Guide.

Change a control point on a spline

This example creates a spline and then changes the first control point for the spline.

Sub Ch4_ChangeSplineControlPoint()

    ' Create the spline

    Dim splineObj As AcadSpline

    Dim startTan(0 To 2) As Double

    Dim endTan(0 To 2) As Double

    Dim fitPoints(0 To 8) As Double

          startTan(0) = 0.5: startTan(1) = 0.5: startTan(2) = 0
          endTan(0) = 0.5: endTan(1) = 0.5: endTan(2) = 0
          fitPoints(0) = 1: fitPoints(1) = 1: fitPoints(2) = 0
          fitPoints(3) = 5: fitPoints(4) = 5: fitPoints(5) = 0
          fitPoints(6) = 10: fitPoints(7) = 0: fitPoints(8) = 0
          Set splineObj = ThisDrawing.ModelSpace. _
       AddSpline(fitPoints, startTan, endTan)
          splineObj.Update
                ' Change the coordinate of the first fit point
          Dim controlPoint(0 To 2) As Double
          controlPoint(0) = 0
          controlPoint(1) = 3
          controlPoint(2) = 0
          splineObj.SetControlPoint 0, controlPoint
          splineObj.Update
      End Sub

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