Find Coordinate of a point

Hi All,

Please help me to find the coordinate of a point at a given distance before the first vertex of a polyline through autolisp.

Hope its clear, if not please ask i'll attach a sample drawing.

Thanks and Regards

Aaryan.

Type ID on the command line then select the point...

Thanks kaizen for your reply, but i want to know it through autolisp.

Below I've attached the drawing for the reference.

Drawing5.dwg

Regards

Specify a point by function (getpoint) then retrieve the variable value with functions (car) , (cadr) and (caddr) .

Thanks Tharwat,

I think I've not made it clear before. Please see my 3rd post in which i have attached a drawing for reference.

Thanks again

Regards

Okay , if you want to specify a point on an entity , you can use the function (vlax-curve-getpointatdist ) .

if not , just read about the function polar e.g (polar ) .

Tharwat

Thanks You So Much Tharwat.

Here's another way:

(defun _getpoint ( ent dis / der )
   (setq der (vlax-curve-getfirstderiv ent (vlax-curve-getstartparam ent))
         dis (/ dis (distance '(0.0 0.0 0.0) der))
   )
   (mapcar '(lambda ( a b ) (- a (* dis b))) (vlax-curve-getstartpoint ent) der)
)

(defun c:test ( / e )
   (if (setq e (car (entsel))) (_getpoint e 50.0))
)

Thank You So Much Lee Mac.

Regards

Aaryan