About Interpreting Variant Arrays (ActiveX)

Calculate the distance between two points

The following code demonstrates calculating the distance between two points input by the user. In this example, the data type is known because all coordinates are doubles. 3D coordinates are a three-element array of doubles and 2D coordinates are a two-element array of doubles.

AutoLISP

(vl-load-com)
(defun c:Ch2_CalculateDistance()
    (setq acadObj (vlax-get-acad-object)
          doc (vla-get-ActiveDocument acadObj)
          utilObj (vla-get-Utility doc))

    ;; Get the points from the user
    (setq point1 (vlax-variant-value (vla-GetPoint utilObj nil "First point: "))
          point2 (vlax-variant-value (vla-GetPoint utilObj point1 "Second point: ")))

    ;; Calculate the distance between point1 and point2
    (setq X (- (vlax-safearray-get-element point1 0) (vlax-safearray-get-element point2 0))
          Y (- (vlax-safearray-get-element point1 1) (vlax-safearray-get-element point2 1))
          Z (- (vlax-safearray-get-element point1 2) (vlax-safearray-get-element point2 2))
          dist (sqrt (+ (expt (sqrt (+ (expt X 2)(expt Y 2))) 2) (expt Z 2))))

    ;; Display the resulting distance
    (alert (strcat "The distance between the points is: " (rtos dist 2)))
)

VBA (AutoCAD Only)

Sub Ch2_CalculateDistance()
    Dim point1 As Variant
    Dim point2 As Variant

    '' Get the points from the user
    point1 = ThisDrawing.Utility.GetPoint(, vbCrLf & "First point: ")
    point2 = ThisDrawing.Utility.GetPoint(point1, vbCrLf & "Second point: ")

    '' Calculate the distance between point1 and point2
    Dim x As Double, y As Double, z As Double
    Dim dist As Double
    x = point1(0) - point2(0)
    y = point1(1) - point2(1)
    z = point1(2) - point2(2)
    dist = Sqr((Sqr((x ^ 2) + (y ^ 2)) ^ 2) + (z ^ 2))

    '' Display the resulting distance
    MsgBox "The distance between the points is: " _
           & dist, , "Calculate Distance"
End Sub