GetBulge Method (ActiveX)

Gets the bulge value at a given index of the polyline.

Supported platforms: Windows only

Signature

VBA:

RetVal = object.GetBulge(Index)

object

Type: LWPolyline, Polyline

The objects this method applies to.

Index

Access: Input-only

Type: Integer

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

Return Value (RetVal)

Type: Double

The bulge value for the vertex at the given index.

Remarks

Polyline: this method will fail if the polyline Type property is not acSimplePoly.

The bulge is the tangent of 1/4 of the included angle for the arc between the selected vertex and the next vertex in the polyline's vertex list. A negative bulge value indicates that the arc goes clockwise from the selected vertex to the next vertex. A bulge of 0 indicates a straight segment, and a bulge of 1 is a semicircle.

Examples

VBA:

Sub Example_GetBulge()
    ' This example creates a lightweight polyline in model space.
    ' It then finds and changes the bulge for a given segment.
    
    Dim plineObj As AcadLWPolyline
    Dim points(0 To 11) As Double
    
    ' Define the 2D polyline points
    points(0) = 1: points(1) = 1
    points(2) = 1: points(3) = 2
    points(4) = 2: points(5) = 2
    points(6) = 3: points(7) = 2
    points(8) = 4: points(9) = 4
    points(10) = 4: points(11) = 1
        
    ' Create a lightweight Polyline object in model space
    Set plineObj = ThisDrawing.ModelSpace.AddLightWeightPolyline(points)
    ZoomAll
    
    ' Find the bulge of the third segment
    Dim currentBulge As Double
    currentBulge = plineObj.GetBulge(3)
    MsgBox "The bulge for the third segment is " & plineObj.GetBulge(3), , "GetBulge Example"
    
    ' Change the bulge of the third segment
    plineObj.SetBulge 3, -0.5
    plineObj.Update
    MsgBox "The bulge for the third segment is now " & plineObj.GetBulge(3), , "GetBulge Example"
    
End Sub

Visual LISP:

(vl-load-com)
(defun c:Example_GetBulge()
    ;; This example creates a lightweight polyline in model space.
    ;; It then finds and changes the bulge for a given segment.
    (setq acadObj (vlax-get-acad-object))
    (setq doc (vla-get-ActiveDocument acadObj))

    ;; Define the 2D polyline points
    (setq points (vlax-make-safearray vlax-vbDouble '(0 . 11)))
    (vlax-safearray-fill points '(1 1
                                  1 2
                                  2 2
                                  3 2
                                  4 4
                                  4 1
                                 )
    )   
        
    ;; Create a lightweight Polyline object in model space
    (setq modelSpace (vla-get-ModelSpace doc))
    (setq plineObj (vla-AddLightWeightPolyline modelSpace points))
    (vla-ZoomAll acadObj)
    
    ;; Find the bulge of the third segment
    (setq currentBulge (vla-GetBulge plineObj 3))
    (alert (strcat "The bulge for the third segment is " (rtos (vla-GetBulge plineObj 3) 2)))
    
    ;; Change the bulge of the third segment
    (vla-SetBulge plineObj 3 -0.5)
    (vla-Update plineObj)
    (alert (strcat "The bulge for the third segment is now " (rtos (vla-GetBulge plineObj 3) 2)))
)