Topic: bounding box along direction

[domenicomaria]

I need to know the red size in the second attached image.
Without rotating anything !
Is it possible ?

[Marc'Antonio Alessi]

Rotate UCS?

[ribarm]

Rotate UCS and apply this routine to get BBox, then extract only width (red line)...

[VovKa]

build a list of coordinates (curves must be approximated)
then either rotate every point around the common center or project them on a red line
then find min and max

some helper functions https://www.theswamp.org/index.php?topic=37319.msg423645#msg423645

[domenicomaria]

Rotate UCS and apply this routine to get BBox, then extract only width (red line)...

Thank you Ribarm!
Works !
But I was hoping for a mathematical solution. . .
Because this routine does a number of very spectacular things,
while I'm looking for something that can't be seen,
that makes calculations "in secret" ...

But I realize that it is a very complicated thing!

I have to try to do something only for lines, circles and arcs...
It shouldn't be hard...

[domenicomaria]

build a list of coordinates (curves must be approximated)
then either rotate every point around the common center or project them on a red line
then find min and max

some helper functions https://www.theswamp.org/index.php?topic=37319.msg423645#msg423645

VovKa you have allways great ideas ...
I will give it a try !
Grazie.
Ciao

[It's Alive!]

If that’s a polyline, made to represent an object, you can store a direction in XData when it’s created.
Then, you can get the direction at a later time, even if it’s been rotated 

[dexus]

I tried to make an example by projecting the lines onto the line and getting the min and max. (like VovKa suggested)
It uses the code from http://www.lee-mac.com/entitytopointlist.html to make the pointlist.

Code - Auto/Visual Lisp: [Select]

1. (defun c:bbang (/ pl lin pts)
2.   (and
3.     (setq pl (car (entsel "\nSelect polyline: ")))
4.     (setq pts (LM:ent->pts pl 50.0)) ; Get point list
5.     (setq line (car (entsel "\nSelect angle line: ")))
6.     (setq line (entget line))
7.     (setq line (list (cdr (assoc 10 line)) (cdr (assoc 11 line)))) ; Start and end point
8.     (setq line (cons (mapcar '- (cadr line) (car line)) line)) ; Add relative point
9.     (setq pts (mapcar (function (lambda (pt) (caddr (trans (mapcar '- pt (cadr line)) 0 (car line))))) pts)) ; get distances on line
10.     (princ "\nDistance on line: ") (princ (- (apply 'max pts) (apply 'min pts))) ; Subtract shortest from longest to get the distance
11.   )
12.   (princ)
13. )

[domenicomaria]

@Dexus

It works very well !

it's enough for what I need !

that's exactly what vovKa suggested !

it's not perfect,
(because it doesn't analyze curves but only segments),
but for what I have to do,
it's fine.

Thank you all.

[domenicomaria]

@Dexus
. . . your modified version has a little problem . . .

[dexus]

@Dexus
. . . your modified version has a little problem . . .

It was missing a bracket, should work now. 

[Marc'Antonio Alessi]

Please post your sample DWG. > Edit...

Code: [Select]

(defun c:test (/ ent line llp urp )
    (and
        (setq ent (car (entsel "\nSelect polyline: ")))
        (setq line (car (entsel "\nSelect angle line: ")))
        (progn
            (command "_.UCS" "_ENTITY" line)           
            (gc:UcsBoundingBox ent 'llp 'urp)
            (command "_.rectangle" "_non" llp "_non" urp)
            (command "_.UCS" "_P")           
        )
    )
    (princ)
)
;; gc:UcsBoundingBox by Gile
;; Returns the UCS coordinates of the object bounding box about current UCS
;;
;; Arguments
;; obj: an entity (ENAME or VLA-OBJCET)
;; _OutputMinPtSym: a quoted symbol (output)
;; _OutputMaxPtSym: a quoted symbol (output)


(defun gc:UcsBoundingBox ( obj _OutputMinPtSym _OutputMaxPtSym )
    (and (= (type obj) 'ename)
         (setq obj (vlax-ename->vla-object obj))
    )
    (vla-transformby obj (vlax-tmatrix (gc:TMatrixFromTo 1 0)))
    (vla-getboundingbox obj _OutputMinPtSym _OutputMaxPtSym)
    (vla-transformby obj (vlax-tmatrix (gc:TMatrixFromTo 0 1)))
    (set _OutputMinPtSym (vlax-safearray->list (eval _OutputMinPtSym)))
    (set _OutputMaxPtSym (vlax-safearray->list (eval _OutputMaxPtSym)))
)


;; gc:TMatrixFromTo by Gile
;; Returns the 4X4 transformation matrix from a coordinate system to an other one
;;
;; Arguments
;; from to: same arguments as for the 'trans' function


(defun gc:TMatrixFromTo ( from to )
    (append
        (mapcar
            (function
                (lambda   ( v o )
                    (append (trans v from to t) (list o))
                )
            )
           '(
                (1.0 0.0 0.0)
                (0.0 1.0 0.0)
                (0.0 0.0 1.0)
            )
            (trans '(0.0 0.0 0.0) to from)
        )
       '((0.0 0.0 0.0 1.0))
    )
)

[domenicomaria]

Please post your sample DWG.

[Marc'Antonio Alessi]

Please post your sample DWG.

[VovKa]

it's not perfect,
(because it doesn't analyze curves but only segments),

LM:ent->pts builds approximations for curves, so it's better than you think