Draw ARC with Bulge

[SZLMCL]

Hy,

 

I would like to draw an arc with AutoCAD VBA. Known the arc start- and endpoint, and the value of the bulge.

 

With LWPolyline it is possible to draw an arc easily so (SetBulge), but i need draw the arc with ThisDrawing.ModelSpace.AddArc command. Here is not Setbulge function. (Addarc need StartAngle, EndAngle, Radius, CenterPoint).

 

How can i draw it?

 

Thanks!

[Lee Mac]

You can derive the necessary arguments from the definition of the bulge:

 

[Lee Mac]

In LISP:

 

;; BulgeData  ~  Lee Mac
;; Args: p1,p2 Points, b Bulge
;; Returns:  (<centre> <inc. angle> <radius>)

(defun BulgeData (p1 p2 b / theta/2 radius centre)
 (setq theta/2 (* 2. (atan b))
       radius  (/ (distance p1 p2) (* 2. (sin theta/2)))
       centre  (polar p1 (+ (- (/ pi 2.) theta/2) (angle p1 p2)) radius))

 (list centre (* 2. theta/2) (abs radius)))

[SZLMCL]

You can derive the necessary arguments from the definition of the bulge:

 

[ATTACH]18688[/ATTACH]

 

Thanks, I managed to solve it in VBA.

[Lee Mac]

Happy to help