GetControlPoint Method (ActiveX)

Gets the coordinates of the control point at a given index.

Supported platforms: Windows only

Signature

VBA:

RetVal = object.GetControlPoint(Index)

object

Type: Spline

The object this method applies to.

Index

Access: Input-only

Type: Integer

The index location of the control point you wish to query. The index must be a positive integer beginning with zero.

Return Value (RetVal)

Type: Variant (three-element array of doubles)

The 3D WCS coordinates of the control point at the given index location.

Remarks

Control points fine-tune a spline definition by adding weight to a portion of the spline curve.

You can query the total number of control points in a spline using the NumberOfControlPoints property. You can set a new coordinate location for a control point by using the SetControlPoint method. You can set a new weight for a control point by using the SetWeight method.

Examples

VBA:

Sub Example_GetControlPoint()
    ' This example creates a spline object in model space.
    ' It then finds the coordinates of the first control point
    ' and changes that value.

    ' 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)
    ZoomAll
    
    ' Display the coordinates of the first control point
    Dim controlPoint As Variant
    controlPoint = splineObj.GetControlPoint(0)
    MsgBox "Control point 1 is at " & controlPoint(0) & ", " & controlPoint(1) & ", " & controlPoint(2), , "GetControlPoint Example"
    
    ' Change the coordinate of the first fit point
    controlPoint(0) = 0: controlPoint(1) = 3: controlPoint(2) = 0
    splineObj.SetControlPoint 0, controlPoint
    splineObj.Update
    MsgBox "Control point 1 is now at " & controlPoint(0) & ", " & controlPoint(1) & ", " & controlPoint(2), , "GetControlPoint Example"
    
End Sub

Visual LISP:

(vl-load-com)
(defun c:Example_GetControlPoint()
    ;; This example creates a spline object in model space.
    ;; It then finds the coordinates of the first control point
    ;; and changes that value.
    (setq acadObj (vlax-get-acad-object))
    (setq doc (vla-get-ActiveDocument acadObj))

    ;; Create the spline
    (setq startTan (vlax-3d-point 0.5 0.5 0)
          endTan (vlax-3d-point 0.5 0.5 0)
          fitPoints (vlax-make-safearray vlax-vbDouble '(0 . 8)))
    (vlax-safearray-fill fitPoints '(1 1 0
                                     5 5 0
                                     10 0 0
                                    )
    )

    (setq modelSpace (vla-get-ModelSpace doc))
    (setq splineObj (vla-AddSpline modelSpace fitPoints startTan endTan))
    (vla-ZoomAll acadObj)
    
    ;; Display the coordinates of the first control point
    (setq controlPoint (vlax-safearray->list (vlax-variant-value (vla-GetControlPoint splineObj 0))))
    (alert (strcat "Control point 1 is at " (rtos (nth 0 controlPoint) 2) ", " (rtos (nth 1 controlPoint) 2) ", " (rtos (nth 2 controlPoint) 2)))
    
    ;; Change the coordinate of the first fit point
    (setq controlPoint (vlax-3d-point 0 3 0))
    (vla-SetControlPoint splineObj 0 controlPoint)
    (vla-Update splineObj)
    (setq controlPoint (vlax-safearray->list (vlax-variant-value (vla-GetControlPoint splineObj 0))))
    (alert (strcat "Control point 1 is now at " (rtos (nth 0 controlPoint) 2) ", " (rtos (nth 1 controlPoint) 2) ", " (rtos (nth 2 controlPoint) 2)))
)