wind_skin
Guest
Hello, I ask you experts if there is a lisp (with .lsp extension) that can determine whether a closed polyline has been drawn clockwise or anti-clockwise.
Thank you in advance.
Thank you in advance.
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lisp to determine whether a polyline is designed clockwise or anticlockwise
confutatis
Guest
This is a program I created time ago to check whether the polyline is clockwise or anti-clockwise. Please note that if the polyline is created with the _bpoly command is always anti-clockwise. if you are interested I also have the program to reverse the sense of polylinea (created to use it on autocad versions that did not have the reverse option of the editpl command).
Attachments
Joseph
Guest
I came across the doslib.arx library, which can be loaded free of charge and easily in autocad, which contains a mine of advanced functions, well documented.
among these the dos_plinewinding function that solves your problem.
(dos_plinewinding entity)
the entity name of a closed polyline.
return
> 0 if the polyline winds to the left.
< 0 if the polyline winds to the right.
0 if unable to determine the winding.
nil on error.
example.
command: (dos_plinewinding (car (entsel "\nselect a closed polyline:"))
-1
among these the dos_plinewinding function that solves your problem.
(dos_plinewinding entity)
the entity name of a closed polyline.
return
> 0 if the polyline winds to the left.
< 0 if the polyline winds to the right.
0 if unable to determine the winding.
nil on error.
example.
command: (dos_plinewinding (car (entsel "\nselect a closed polyline:"))
-1
confutatis
Guest
the purpose was to solve everything without installing additional libraries. It happened to me again to propose doslib to solve another problem. the interlocutor has categorically refused. . .
Joseph
Guest
and what should be the problem? are free, they are not heavy.. .the purpose was to solve everything without installing additional libraries. It happened to me again to propose doslib to solve another problem. the interlocutor has categorically refused. . .
and then the express tools are not also an external library?
confutatis
Guest
often my programs must create them without the help of external libraries. Unfortunately, I must also consider the possibility that someone has not installed express tools, although very inconvenience.
But I must say that this is a bit different here.
But I must say that this is a bit different here.
wind_skin
Guest
I thank both for the help and interest; I will try and update you. In fact, I need a function to insert into a little program that I intend to write and that I will need to produce a gcode for the tool path of a cnc directly from autocad. It is good that there are specific software for this purpose, but I would also like to try.
Thanks again: you are very kind.
Thanks again: you are very kind.
wind_skin
Guest
confutatis, I just tried to load the lisp you kindly attached, but it gives me the following error in loading phase "; error: incorrect list in the input".This is a program I created time ago to check whether the polyline is clockwise or anti-clockwise. Please note that if the polyline is created with the _bpoly command is always anti-clockwise. if you are interested I also have the program to reverse the sense of polylinea (created to use it on autocad versions that did not have the reverse option of the editpl command).
I tried both with 2008 and 2011. more precisely, the viewer is the following:
"command: _appload plor.lsp loaded. "
"command: ; error: wrong list in input"
confutatis
Guest
GP.
Guest
My dear leemax, these are the side effects of the "third age". :biggrin:I forget. . .
wind_skin
Guest
thanks confutatis, your program works egregiously with all the types of polylinea that I had the opportunity to try, except those closed composed only by a circle arc and a segment (it is not because).once so much that I remember the (vl-load-com), I forget the brackets, bah...
Thanks again, you were very kind and precious.
confutatis
Guest
with only two vertices how do you understand the clock or anti-clockwise? I thought the least was three...
wind_skin
Guest
I agree with you: it takes at least three vertices. the third summit (the missing one) could be the average point of the circle arc.with only two vertices how do you understand the clock or anti-clockwise? I thought the least was three...
confutatis
Guest
I was inspired and created this: in all two-sided polylines and one of the two sides is a circle arc, on the same a third summit is inserted on the average point.the third summit (the missing one) could be the average point of the circle arc.
all this by exploiting the powerful vlisp functions of entity management.
Attachments
wind_skin
Guest
hi confutatis, I tried the program you wrote, but I didn't get the desired result (I don't know where I'm wrong). I attach a file containing an example of closed polylinea composed of a circle arc and a segment: If you have time (I don't want to take advantage of your kindness), take a look.I was inspired and created this: in all two-sided polylines and one of the two sides is a circle arc, on the same a third summit is inserted on the average point.
all this by exploiting the powerful vlisp functions of entity management.
Thank you.
Attachments
confutatis
Guest
No, you're not wrong, I'm the one who didn't consider other possibilities. in the specific case the original vertices were not two but three, the last was coincident with the first, but, for the purposes of programming, a closed polyline with n vertices is different from an open polyline with n+1 vertices, of which the first and the last coincidence, even if to video are identical.
Attachments
wind_skin
Guest
Okay, I try and let you know.
Thank you.
Thank you.
wind_skin
Guest
confutatis, I tried your program and it works. In summary, I believe I have understood that, if you have to deal with a closed polylinea composed of a circle arc and a segment, you must first start "aumver" and then bend the orientation by "plor". correct me if I'm wrong. Now I will try to join the two programs in one: I hope I can.
thanks for your availability and kindness.
thanks for your availability and kindness.
confutatis
Guest
Yes, I actually left the two separate programs, since aumver could only serve me occasionally. Anyway, if you want to have fun joining them, go ahead! :smile:
confutatis
Guest
the time/time sense only makes sense on closed polylines. What's the point of giving an open polyline? for these just the reverse command. at the limit I can remove from the selection all the open polylines. . .