trace a perpendicular line with lisp

[Angelo2449]

Hello.

I am trying to track a line perpendicular to a previously tracked using autolisp but, even after countless attempts I failed in the intent.

This should be code :

(command-s "_line" point1 point2")
(command-s "_line" pointo "-per" point1 point2")

the second instruction should draw a line from the point "point" perpendicular to the point1 point2 line but this does not happen.

Thank you.

 

[dieva]

Hello.

I am trying to track a line perpendicular to a previously tracked using autolisp but, even after countless attempts I failed in the intent.

This should be code :

(command-s "_line" point1 point2")
(command-s "_line" pointo "-per" point1 point2")

the second instruction should draw a line from the point "point" perpendicular to the point1 point2 line but this does not happen.

Thank you.

prova:

(command "_line" point1 point2")
(command "_line" p3 (osnap point2 "per") "")

 

[Angelo2449]

It doesn't work.

It is impossible to apply the concept of perpendicularity using only one point (point2).

apart from the error contained in my post "-per" instead of "_per", the concept is that, the syntax is wrong, in fact it generates a mistake.

I tried to use "_last" instead of "point1 point2" but it doesn't work, I always think for wrong syntax.

Thank you.

 

[dieva]

It doesn't work.

It is impossible to apply the concept of perpendicularity using only one point (point2).

to work, from point 2 point 2 it must pass another line or another entity... otherwise.. .

 

[GP.]

...I try to trace a line perpendicular to a previously tracked using autolisp but, even after countless attempts I failed in the intent.

you have to calculate the point and then use it to create the line.

;; project point onto line  -  lee mac
;; projects pt onto the line defined by p1,p2

(defun lm:projectpointtoline ( pt p1 p2 / nm )
    (setq nm (mapcar '- p2 p1)
          p1 (trans p1 0 nm)
          pt (trans pt 0 nm)
    )
    (trans (list (car p1) (cadr p1) (caddr pt)) nm 0)
)

 

[Cristallo]

becomes much easier to temporarily activate via lisp a perpendicular osnap

(setq oldosmode (getvar "osmode")); preserves the current state of osnap
(setvar "osmode" 128); septa l'osnap a perpendicular

... routine line creation (poiche l'osnap is activated pointing in a x,y point becomes secondary to the osnap)
...
...

(setvar "osmode" oldosmode) ; it restores the original value of the osnap before the procedure.

In this way, without coordinate calculations, I managed to trace a tangent line to 2 circles one on the upper dial and one on the lower dial.