Topic: Arc with START, END, MIDDLE points?

[domenicomaria]

pay attention :

I modified the code of my last two posts !

[domenicomaria]

Lisp has no other function that supports previewing except for grread, unless you load the real-time capture function of ENTITYJIG written in C # or C++

BricsCAD has GRARC

(GRARC  ptCenter  radius  startAng  endAng  color  [minsegments  [highlight]])

this function draws a "temporary graphics" arc or circle, with specified radius and color; optionally in highlighted mode.

But i don't believe that it is enough !

[ribarm]

Here is another that I think satisfy your request... It only previews CIRCLE instead of ARC...

Code - Auto/Visual Lisp: [Select]

1. (defun c:3pcir-arc ( / st en li p1 p2 )
2.  
3.   (vl-load-com)
4.  
5.   (initget 1)
6.   (setq st (getpoint "\nPick or specify start point : "))
7.   (initget 1)
8.   (setq en (getpoint st "\nPick or specify end point : "))
9.   (setq li (entmakex (list (cons 0 "LINE") (cons 10 (trans st 1 0)) (cons 11 (trans en 1 0)))))
10.   (vl-cmdf "_.CIRCLE" "_3P" "_non" st "_non" en "\\")
11.   (setq p1 (trans (vlax-curve-getpointatparam (entlast) (+ (vlax-curve-getparamatpoint (entlast) (trans st 1 0)) 0.01)) 0 1))
12.   (setq p2 (trans (vlax-curve-getpointatparam (entlast) (- (vlax-curve-getparamatpoint (entlast) (trans st 1 0)) 0.01)) 0 1))
13.   (vl-cmdf "_.TRIM" li "" "_non" p1 "")
14.   (initget "Yes No")
15.   (if (= "No" (cond ( (getkword "\nIs ARC on good side [Yes / No] <Yes> : ") ) ( "Yes" )))
16.     (progn
17.       (vl-cmdf "_.UNDO" 1)
18.       (vl-cmdf "_.TRIM" li "" "_non" p2 "")
19.     )
20.   )
21.   (entdel li)
22.   (princ)
23. )
24.  

HTH.
M.R.

[glfiedler]

ribarm,
Thank you for sharing this lisp routine. It is perfect for the way I prefer to draw arc.

[V@no]

Using 3-point-circle as preview:

Code - Auto/Visual Lisp: [Select]

1. (DEFUN c:3parc (/ p1 p2 p3)
2.     (SETVAR "cmdecho" 0)
3.     (SETQ p1 (GETPOINT "Specify start point:"))
4.     (SETQ p2 (GETPOINT p1 "\nSpecify end point:"))
5.     (PRINC "\nSpecify middle point:")
6.     (COMMAND "_.CIRCLE" "_3p" "_non" p1 "_non" p2 "\\")
7.     (SETQ p3 (GETVAR 'lastpoint))
8.     (COMMAND "_.UNDO" "1") ;remove circle
9.     (COMMAND "_.ARC" "_non" p1 "_non" p3 "_non" p2) ;draw arc
10.     (SETVAR "cmdecho" 1)
11.     (PRINC)
12. )