spline from a list

[SELFCAD]

Hi guys,

I have a list with point's coordinates, i want to draw a spline through these points, which is the best way? (or which is the way ? Thanks!

[Lee Mac]

I would recommend the AddSpline method, using entmake with Splines can be very complex.

[SELFCAD]

Maybe you have a lisp with this method? A sample...

[SELFCAD]

I found this code by google. Seems to replace y with z and z with y for every fit point of a spline. Why?

(setq a (entget (car (entsel "\nSelect SPLine: "))))
 (foreach b a
   (if    (= (car b) 11)
     (setq Pdata
        (append Pdata
            (list (cdr b))
        )
     )
   )
 )

[MSasu]

I'm afraid that that excerpt of code that not replace anything; it only gather all fit points to a list.

 

Regards,

Mircea

Edited February 2, 2012 by MSasu

[SELFCAD]

Sorry, my mistake, something wrong with ucs....sorry!

[MSasu]

Not sure what your excerpt of code had to do with the UCS - please keep in mind that the points in associated lists are kept in WCS coordinates.

 

By the way, even if the solutions suggested by Lee Mac are far better, a easy way to draw a spline entity from a list of points is:

 

(command "_SPLINE")              ;start the command
(foreach thePoint MyPointsList   ;parse points list
(command thePoint)
)
(command "" "" "")               ;accept default tangents & end the command

 

Regards,

Mircea

[SELFCAD]

Thanks Mircea!

[MSasu]

You're welcome!

Did you managed to integrate in your code the given example?

 

Regards,

Mircea

[Stefan BMR]

The entmake way, for a list of points lst:

(entmake
      (append
        (list
          '(0 . "SPLINE")
          '(100 . "AcDbEntity")
          '(100 . "AcDbSpline")
          '(70 . 40)
          '(71 . 3)
          (cons 74 (length lst))
          '(44 . 1.0e-005)
          )
        (mapcar '(lambda (x) (cons 11 x)) lst)
        )
      )

Same result as (command "Spline" ...

[SELFCAD]

Perfect! Thanks, Stefan!

I did it, Mircea.

[SELFCAD]

if i have a list with points, Pdata, p - a point from Pdata, a fix point px - not from Pdata, and a given value for Distance - let's say 10, can i set a point pd in this way?

 

(if (and (/= (member p Pdata) nil)
    (= (Distance p px) 10))
 (setq pd p))

[MSasu]

So you want to retain a point if he matches simultaneously two conditions: (1) belong to list Pdata and is located at exactly 10 units of a given point px? If true, your code is OK - have made a small correction:

(if (and (member p Pdata)
        (= (Distance p px) 10))
(setq pd p)
)

 

You may test your code parts (unit testing) on Console window of VLisp editor.

 

Regards,

Mircea

[SELFCAD]

How can i remove the first element from a selection set?

i have:

(setq ss (ssget '((0 . "point"))))

 

and i want to set now something like this:

(setq ss1 (cdr ss)) - this is not possible, but how to do it?

[Lee Mac]

(ssdel (ssname ss 0) ss)