array dimensions

[eg0n]

I want to fill an array with the elements of a list. The problem is that when I want to define the dimensions of the array, the upper bound depends on the length of my list so I use the following code:

 

(setq array (vlax-make-safearray vlax-vbDouble '(0 . (- (length newlist) 1))))

 

and I get a "bad argument type: fixnump: (- (LENGTH NEWLIST) 1)" error.

 

Any ideas would be really helpful. :?

[Tharwat]

Sine that you have started and wrote some codes of your desired routine , it's better to post all of them to check them out or may add ours for you to use .

 

Thanks.

 

Tharwat

[eg0n]

What I'm trying to do is to simplify a polyline by removing not important points. As "not important" I define every point which is inside an angle. At the following image point 3 is not important (inside angle) but point 5 is important.

 

 

;(prompt "\nType \"mine\" to run........")

(defun c:mine ( / theobj thelist n xval1 yval1 newlist maxdeg amax xval2 yval2 xval3 yval3 d1 d2 d3 z a l anarray mspace myobj)
                           
;load the visual lisp extensions
(vl-load-com)
                           
;get the entity and entity name
(setq theobj (car (entsel "\nSelect a Polyline: ")))
                           
;convert to vl object
(setq theobj (vlax-ename->vla-object theobj))

;retrieve the coordinates
(setq thelist (vlax-get-property theobj 'coordinates))

;convert to a list
(setq thelist (vlax-safearray->list  (variant-value thelist)))

;zero the counter
(setq n 0)

;make a list of the simplified coordinates
(setq xval1 (car thelist))
(setq yval1 (cadr thelist))
(setq newlist '(xval1 yval1))

;ask for maximum angle
(setq maxdeg (getint "\nEnter Maximum Angle (0 - 90 deg) : "))

;convert degrees to radians using "dtr" routine
(setq amax (dtr maxdeg))

;start the loop and repeat it for (n-2) times
(repeat (- (/ (length thelist) 2) 2)

;get the x coordinates
(setq xval1 (nth n thelist))
(setq xval2 (nth (+ 2 n) thelist))
(setq xval3 (nth (+ 4 n) thelist))

;increase the counter
(setq n (1+ n))

;get the y coordinates
(setq yval1 (nth n thelist))
(setq yval2 (nth (+ 2 n) thelist))
(setq yval3 (nth (+ 4 n) thelist))

;calculate distances using "distan" routine
(setq d1 (distan xval1 xval2 yval1 yval2)) 
(setq d2 (distan xval1 xval3 yval1 yval3))
(setq d3 (distan xval2 xval3 yval2 yval3)) 

;calculate angle
(setq z (/ (- (+ (expt d1 2) (expt d2 2)) (expt d3 2)) (* 2 (* d1 d2))))   
(setq a (arccos z))

;compare the angles
(if (> a (/ amax 2))

;if true do the following
(progn  
 
;add the coordinates to the new list
(setq newlist (append '(newlist xval3 yval3)))

);progn

);if

;increase the counter
(setq n (1+ n))

);repeat

;add the last point to the simplified list
(setq xval1 (nth (- (length thelist) 1) thelist))
(setq yval1 (last thelist))
(setq newlist (append '(newlist xval1 yval1)))

;make an array with the points of the simplified list
(setq anarray (vlax-make-safearray vlax-vbDouble '(0 . (- (length newlist) 1))))

;fill it with x and y values
(vlax-safearray-fill anarray newlist)

;reference to model space
(setq mspace (vla-get-modelSpace (vla-get-activeDocument (vlax-get-acad-object))))

;draw the simplified polyline
(setq myobj (vla-addLightweightPolyline mspace anarray))

(princ)

);defun

;------------------------------------------
;This function converts Degrees to Radians.
(defun dtr (x)
;define degrees to radians function
(* pi (/ x 180.0))
;divide the angle by 180 then
;multiply the result by the constant PI
) ;end of function

;clean loading
(princ)

;This function calculates distance
(defun distan (x1 x2 y1 y2)

;calculate dx dy
(setq pt1 (list x1 y1))
(setq pt2 (list x2 y2))

;find the distance
(distance pt1 pt2)

) ;end of function

;clean loading
(princ)

;This function inverse cosine (ArcCos)
;Args: -1 <= x <= 1

(defun arccos (x)
 (atan (/ (sqrt (- 1 (expt x 2))) x))
)

;clean loading
(princ)

;-------------------------------------------


;End of mine.lsp
;---------------------------

 

The problem is when I try to draw the simplified polyline by using the values that I have stored at a list, because it cannot accept the following:

 

(setq anarray (vlax-make-safearray vlax-vbDouble '(0 . (- (length newlist) 1))))

 

thank you for your help

[Lee Mac]

The problem is the use of an apostrophe - meaning that the expressions following the apostrpohe are not evaluated.

 

Read this:

http://www.cadtutor.net/forum/showpost.php?p=258390&postcount=20

 

I haven't looked through your code, but to solve the issue at hand:

 

(setq anarray (vlax-make-safearray vlax-vbDouble (cons 0 (- (length newlist) 1))))

[eg0n]

I made the change Lee suggested and it's ok (thank you Lee!!!) but now at the next line of code:

 

(vlax-safearray-fill anarray newlist)

 

i get a "lisp value has no coercion to VARIANT with this type: NEWLIST" error.

what does it mean?

[Lee Mac]

Look at how you are constructing 'newlist' - are you sure you read my link...

[eg0n]

proud for making my first lisp. Thank you Lee for your help and for your link (I read it the second time and corrected many errors...).