Arc to Polyline bulge

I've found a lot of lisp routines for calculating the centerpoint, radius and included angle of an arc from the two points and the bulge factor of a polyarc. But I can't seem to find a routine to go in reverse.
Does anyone have something that I can get the two points and the bulge factor from inputing the centerpoint, radius and included angle.

 

Here's one that will give you the bulge factor of the picked arc.

Code:

;03-05-03
;Bill Zondlo
;program to pick arc and get bulge
;
;
;
;
;---------;
(defun c:bulge_of_arc ()
;-------------------;
(setq e 1)                                                     ;select first entity.
(while e
(setq en1 (car (entsel "\nSelect arc"))
)
(cond ((null en1)
(prompt "\nNot a Arc.")                             ;loops for null pick.
)
((= (cdr (assoc 0 (entget en1))) "ARC")                ;must be arc.
(setq e nil
pt1 (cdr (assoc 10 (entget en1)))
an1 (cdr (assoc 50 (entget en1)))
an2 (cdr (assoc 51 (entget en1)))
2pi (* pi 2.0)
)
)                                                    ;end list
)                                                           ;end cond.
)                                                             ;end while.
;------------------;
;------------------;
(setq aa (- an1 an2)                                             ;deflection (included) angle
)
(if (not (minusp aa))                                            ;minus is the included (inside) angle.
(setq aa (- 2pi aa))
)
(setq testa aa
aa (abs (/ aa 4.0))                                         ;you need the tangent of this angle (bulge factor).
bulge_1 (* (/ 1.0 (cos aa))(sin aa))                        ;tangent of 1/4 included angle or bulge.
)
;------------------;
)                                                                ;end defun

Bll

 

Thanks Bill for the conversion routine I could use that in the future........I think I am going about this the wrong way entirely.

What I was trying to do was select an existing hatch and the routine would draw the boundary around it.

I have drawings that have hatches with no boundaries. If I make a change to the drawing and want to change the hatch. I don't want to have to redraw the hatch all over again. I just want to get the existing boundary and reselect the interior points. Is there another way of doing this or a lisp file for this.
I'm trying to extract the information from the hatch and either entmake or redraw the polyline. I start getting into trouble when there are arcs involved. Any help would be much appreciated.

 

http://www.jtbworld.com/lisp/hatchb.htm

--
Autodesk Discussion Group Facilitator

would draw the boundary around it.

 

WOW! I should have asked that in the first place. That is a DEFINATE time saver.....Thanks.

 

Send Jimmy an email and say thanks....

--
Autodesk Discussion Group Facilitator

time saver.....Thanks.

 

"Jimmy's got some new moves."

http://www.seinfeldscripts.com/TheJimmy.htm