# TheSwamp

## Code Red => AutoLISP (Vanilla / Visual) => Topic started by: Joe Burke on May 20, 2008, 12:16:36 PM

Title: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 20, 2008, 12:16:36 PM

Group: autodesk.autocad.customization Tony Tanzillo <tony.tanzi...@worldnet.att.net> wrote in article <3664CFB1.
93B45...@worldnet.att.net>... Bob - This isn't remotely close to what he needs.
AutoCAD can't find the minimum clearance between two objects as Microstation can.

I think Tony is wrong about this. I wrote an alorithm which works in most cases for any two curve objects. The function is about eight lines of code. Can you guess how it works?

Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 20, 2008, 03:38:48 PM
The only way I can think of doing it is by stepping points on one object and using vlax-curve-getclosestpointto to the other object. Then store the two points and distance in a list then sort the list by shortest distance :?

How'd you do it Joe?
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 20, 2008, 04:18:11 PM
to use vlax-curve-getclosestpointto on arcs one will have to build an approximation and that is not 100% accurate
Title: Re: Minimum distance between two vlax-curve objects
Post by: Kerry on May 20, 2008, 06:34:57 PM

Group: autodesk.autocad.customization Tony Tanzillo <tony.tanzi...@worldnet.att.net> wrote in article <3664CFB1.
93B45...@worldnet.att.net>... Bob - This isn't remotely close to what he needs.
AutoCAD can't find the minimum clearance between two objects as Microstation can.

I think Tony is wrong about this. I wrote an alorithm which works in most cases for any two curve objects. The function is about eight lines of code. Can you guess how it works?

Joe, I haven't seen the thread, but was the reference to the OutOfTheBox application. ?
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 20, 2008, 10:12:08 PM
Kerry,

I don't have time for a full reply now.

I'll just say I think Tony meant vanilla AutoCAD. Does some vertical app have a minimum distance tool?

More later...
Title: Re: Minimum distance between two vlax-curve objects
Post by: daron on May 21, 2008, 09:34:13 AM
Quote
...minimum clearance...
ADT can for stair openings, so why wouldn't other apps be able to?
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 21, 2008, 09:54:08 AM
I thought I posted this, but later I don't see it.

Here's some beta code which demonstrates the idea. It should work in the vast majority of typical cases. I'm aware there are a few odd cases where it will not. I'm working on those. See inline comments.

Comments and suggestions welcome.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 21, 2008, 10:26:59 AM
to use vlax-curve-getclosestpointto on arcs one will have to build an approximation and that is not 100% accurate

Given there's no such thing as 100% accurate within AutoCAD, try the code I posted.

It uses an approximation method for all supported object types because one sub-routine can process all object types. IOW, a lot less code than would be needed if the line to line condition used a specific sub-routine. Which is possible.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 21, 2008, 10:36:47 AM
The only way I can think of doing it is by stepping points on one object and using vlax-curve-getclosestpointto to the other object. Then store the two points and distance in a list then sort the list by shortest distance :?

How'd you do it Joe?

Something like that, but without using vl-sort. See the MD:ObjObj sub-function in the code I posted.
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 21, 2008, 10:44:26 AM
Here's my "ghetto-fied" solution... :-D

Code: [Select]
`(defun rjp-getmindistof2curveobjs       (div / inc len lst n obj1 obj2 pt1 pt2)  (if (and (setq obj1 (car (entsel "\nSelect first curve object: ")))    (setq obj2 (car (entsel "\nSelect second curve object: ")))      )    (progn      (setq len (vlax-curve-getdistatparam   obj1   (vlax-curve-getendparam obj1) )     n 0.0     inc (/ len div)      )      (repeat div (setq pt1 (vlax-curve-getpointatdist obj1 n)       pt2 (vlax-curve-getclosestpointto obj2 pt1)       n   (+ inc n)       lst (cons (list (distance pt1 pt2) pt1 pt2) lst) )      )      (setq lst (vl-sort lst (function (lambda (d1 d2)      (< (car d1) (car d2))    ) ) )     lst (car lst)      )      (grdraw (cadr lst) (caddr lst) 1)      lst    )  ))(rjp-getmindistof2curveobjs 1000)`
*removed line creation and added vector
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 21, 2008, 11:06:49 AM
Here is my first try. :-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 21, 2008, 11:37:16 AM
Here is my first try. :-)

Hi Alan,

I haven't tried your code, but it looks right.

As I said to ronjonp, there's really no reason to make a list of distances and then use the min or the vl-sort function.

And I think setting step to (/ len 1000) is total overkill. You don't need that many iterations if your code works like mine.

Regards
Joe
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 21, 2008, 11:42:00 AM
Here is my first try. :-)

And I think setting step to (/ len 1000) is total overkill...

Regards
Joe

Depends on the length of the items tested...if the lines are 10000 ft long then the check is only every 10 feet  :-P
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 21, 2008, 11:55:57 AM
Here is my first try. :-)

And I think setting step to (/ len 1000) is total overkill...

Regards
Joe

Depends on the length of the items tested...if the lines are 10000 ft long then the check is only every 10 feet  :-P

Not correct. The length of the objects involved is not an issue. Study my code.
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 21, 2008, 12:01:27 PM
to use vlax-curve-getclosestpointto on arcs one will have to build an approximation and that is not 100% accurate

Given there's no such thing as 100% accurate within AutoCAD, try the code I posted.

my reply concerned Ron's suggestiong, but your tricky approach is a wow :)
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 21, 2008, 12:14:01 PM
Here is my first try. :-)

And I think setting step to (/ len 1000) is total overkill...

Regards
Joe

Depends on the length of the items tested...if the lines are 10000 ft long then the check is only every 10 feet  :-P

Not correct. The length of the objects involved is not an issue. Study my code.

Joe,

I was referring to my code...I tried your code but got different results depending on where my pick points were (but there's been one or more times where I don't understand what's going on)  :-D
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 21, 2008, 12:35:17 PM
it's my try Joe
sometimes 5 repetitions are enough and sometimes 30 are not
let the code itself decide when it is enough :)
Code: [Select]
`(defun MD:ObjObj (obj1 obj2 pt / p d fuzz)  (setq fuzz 1E-8)  (while (not    (equal (distance pt (setq p (vlax-curve-GetClosestPointTo obj2 pt)))   (setq d (distance p (setq pt (vlax-curve-GetClosestPointTo obj1 p))))   fuzz    ) )  )  (list d pt p))`
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 21, 2008, 12:47:39 PM
Here is an example of a difficult situation.

My code will work if one of the ellipses is selected as indicated. I don't mean to imply this is a good solution. It's just something I'm working on...
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 21, 2008, 12:51:49 PM
it's my try Joe
sometimes 5 repetitions are enough and sometimes 30 are not
let the code itself decide when it is enough :)
Code: [Select]
`(defun MD:ObjObj (obj1 obj2 pt / p d fuzz)  (setq fuzz 1E-8)  (while    (progn (setq pd)    (not      (equal (setq d (distance p (setq pt (vlax-curve-GetClosestPointTo obj1 p))))     (distance pt (setq p (vlax-curve-GetClosestPointTo obj2 pt)))     fuzz      )    )    )  )  (list d pt p))`

That makes sense :-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 21, 2008, 01:00:18 PM
i've made some changes to my code, sorry for stupid errors :)
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 21, 2008, 01:11:53 PM
Joe,
There is a problem with this scenario.
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 21, 2008, 01:27:56 PM
one more situation
Title: Re: Minimum distance between two vlax-curve objects
Post by: Arch_Eric on May 21, 2008, 02:22:32 PM
No need to sort since you're only looking for one point, right?

Code: [Select]
`(defun c:getshortdist ( / shortdist osm col ent1 ent2 step iter ent1-cp ent2-cp clist) (setq osm (getvar "osmode")) (setq col (getvar "cecolor")) (setvar "osmode" 0) (setq ent1 (car (entsel "\nSelect first curve: "))) (setq ent2 (car (entsel "\nSelect second curve: ")));(setq step (getreal "\nEnter step value: ")) (setq step 0.1) (setq iter step) (while (vlax-curve-getPointAtDist ent1 iter)  (setq ent1-cp (vlax-curve-getPointAtDist ent1 iter))  (setq ent2-cp (vlax-curve-getClosestPointTo ent2 ent1-cp))  (setq cp-dist (distance ent1-cp ent2-cp))  (setq clist (list cp-dist ent1-cp ent2-cp))  (if (or (= shortdist nil) (< (car clist) (car shortdist))) (setq shortdist clist))  (setq iter (+ iter step)) ) (setvar "cecolor" "210") (command "_line" (cadr shortdist) (caddr shortdist) "") (command "point" (cadr shortdist)) (command "point" (caddr shortdist)) (setvar "cecolor" col) (setvar "osmode" osm))`
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 22, 2008, 05:51:32 AM
Thanks to all who replied.

I'll study the posted code and see what can be done to fix the problems.
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 22, 2008, 08:40:57 AM
And I think setting step to (/ len 1000) is total overkill...

Regards
Joe

Depends on the length of the items tested...if the lines are 10000 ft long then the check is only every 10 feet  :-P
I work in inch units so my typical worst case would be site work with a 250' lot line. In this
case the 3000 inch plines would mean a check every 3 inches. The 1000 is reasonably fast
on my machine in ACAD2000. So that is what I used as well. The alternative is more code.
In fact it would need some intelligent code. For plines the check would need to be at and
midway between each vertex. That would catch a bulge. For circles, ellipses & arcs you
could check using a "Bracket" algorithm. So I think you get my drift.
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 22, 2008, 08:42:24 AM
Joe,
I really like your shortest distance feed back code.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 22, 2008, 10:39:43 AM
To all who replied.

The problems VovKa pointed out were essentially the ones I was aware of as noted in my first code post. At first glance they seemed hard to solve. But after some thinking, it seems not.

Attached is beta version 2. I hope it solves those problems without much additional code/overhead.

Please let me know if you find a case where it does not work as expected.

BTW, there are some bells and whistes I intend to add. The main one is report when two lines or rays or xlines are parallel. There should also be testing for coplanar objects.

Regards and thanks...
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 22, 2008, 10:57:06 AM
Joe,
I really like your shortest distance feed back code.

Thanks, Alan. The idea behind it is you don't have to check for points along the entire length of each object.
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 22, 2008, 12:21:38 PM
more AI should be employed
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 22, 2008, 01:55:23 PM
This is my version 2. Added grdraw
Code: [Select]
`;; CAB @ TheSwamp.org - 5/22/2008;; Version 2 ;; Returns the minimum distance between two objects. ;; Supported object types: any vlax-curve object;;(defun c:MD() (c:MinDist))(defun c:MinDist (/ step e1 e2 p1 p2 len idx dis dlst               curveOK getent)  (vl-load-com)  ;;  CAB test to see if vlax-curve can be used on an object  (defun curveOK (ent) ; returns nil if not allowed    (not (vl-catch-all-error-p           (vl-catch-all-apply 'vlax-curve-getendparam (list ent))         )    )  )  ;; returns an entity which can be used with vlax-curve  (defun getent (pmt / ent)    (while (not (and (setq ent (car (entsel pmt)))                (curveOK ent)           ))      (prompt "\nMissed or not a Curve object. Try again.")    )    ent  )  ;;=========================================================  (setq e1 (getent "\nFirst entity."))  (setq e2 (getent "\nSecond entity."))  (setq len  (vlax-curve-getdistatparam e1 (vlax-curve-getendparam e1)))  (setq idx  0.0        step (/ len 1000)   )  (cond    ((vlax-invoke       (vlax-ename->vla-object e1) 'IntersectWith                  (vlax-ename->vla-object e2) acExtendNone)     (setq dis 0.0)    )    (t     (while (and (<= idx len)                 (setq p1 (vlax-curve-getpointatdist e1 idx))                 (setq p2 (vlax-curve-getclosestpointto e2 p1))            )       (setq dis (distance p1 p2)             idx  (+ idx step)       )       (if (or (null dlst) (< dis (car dlst)))         (setq dlst (list dis p1 p2))       )                   )     (if (and dlst (listp dlst))       (grdraw (trans (cadr dlst)0 1)(trans (caddr dlst)0 1) 6 1)     )    )  )  (print dis)  (princ))(prompt "\nMinimum Distance Loaded, Enter MD to run.")(princ)`
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 22, 2008, 04:47:09 PM
the weakest link in Alan's code is (setq step (/ len 1000)), to eleminate this i suggest stealing Joe's idea like this:
Code: [Select]
`(defun 2ObjDist (obj1 obj2 pt / p d fuzz)  (setq fuzz 1E-8)  (while (not    (minusp      (- (distance pt (setq p (vlax-curve-GetClosestPointTo obj2 pt))) (setq d (distance p (setq pt (vlax-curve-GetClosestPointTo obj1 p)))) fuzz      )    ) )  )  (list d pt p))`and placing it...
Code: [Select]
`(t     (while (and (<= idx len)                 (setq p1 (vlax-curve-getpointatdist e1 idx))                 (setq p2 (vlax-curve-getclosestpointto e2 p1))            )       (setq dis (distance p1 p2)             idx  (+ idx step)       )       (if (or (null dlst) (< dis (car dlst)))         (setq dlst (list dis p1 p2))       )                   )     (setq dlst (2ObjDist e1 e2 (cadr dlst)));<----------- right here     (if (and dlst (listp dlst))       (grdraw (trans (cadr dlst)0 1)(trans (caddr dlst)0 1) 6 1)     )    )`
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 23, 2008, 06:17:06 AM
This is my version 2. Added grdraw

Alan,

I noticed a minor problem with your code. I'd suggest this change at the end.

;  (print dis)
(print (car dlst))

While testing with two full ellipses I found it would return the right answer only if I picked the objects in a certain order. In the opposite order the answer was very different.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 23, 2008, 06:26:45 AM
more AI should be employed

VovKa,

Thanks for the example. Agreed, my latest code doesn't fix that one.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 23, 2008, 06:43:23 AM
the weakest link in Alan's code is (setq step (/ len 1000)), to eleminate this i suggest stealing Joe's idea like this:

VovKa,

I tried your function within Alan's code. Given the two ellipses example, I see a 5% increase in accuracy.

Thank you for your keen insights into the issues involved.

I think I'm going to have to do something similar to Alan's approach to ensure the correct point is passed to the function which sharpens accuracy with irregular curves like splines and ellipses.
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 23, 2008, 09:45:08 AM
OK here is version 3 with the 2ObjDist subroutine.
Great subroutine by the way. Who get the credit for it? 8-)
Code: [Select]
`;; CAB @ TheSwamp.org - 5/23/2008;; Version 3 ;; Returns the minimum distance between two objects. ;; Supported object types: any vlax-curve object;;(defun c:MD() (c:MinDist))(defun c:MinDist (/ step e1 e2 p1 p2 len idx dis dlst               curveOK getent)  (vl-load-com)  ;;  CAB test to see if vlax-curve can be used on an object  (defun curveOK (ent) ; returns nil if not allowed    (not (vl-catch-all-error-p           (vl-catch-all-apply 'vlax-curve-getendparam (list ent))         )    )  )  ;; returns an entity which can be used with vlax-curve  (defun getent (pmt / ent)    (while (not (and (setq ent (car (entsel pmt)))                (curveOK ent)           ))      (prompt "\nMissed or not a Curve object. Try again.")    )    ent  )  ;;  get the min distance between 2 objects nearest to pt  ;;  pt should be a point on obj1  (defun 2ObjDist (obj1 obj2 pt / p d fuzz)    (setq fuzz 1E-8)    (while (not     (minusp       (- (distance pt (setq p (vlax-curve-GetClosestPointTo obj2 pt)))  (setq d (distance p (setq pt (vlax-curve-GetClosestPointTo obj1 p))))  fuzz       )     )  )    )    (list d pt p)  )  ;;=========================================================  (setq e1 (getent "\nFirst entity."))  (setq e2 (getent "\nSecond entity."))  (setq len  (vlax-curve-getdistatparam e1 (vlax-curve-getendparam e1)))  (setq idx  0.0        step (/ len 100) ; 100 may need to increase for very large unit objects  )  (cond    ((vlax-invoke       (vlax-ename->vla-object e1) 'IntersectWith                  (vlax-ename->vla-object e2) acExtendNone)     (setq dis 0.0)    )    (t ; find the min distance within the steps. The accuracy is limited by the     ;;  number of steps, then 2ObjDist is used to increase the accuracy     (while (and (<= idx len)                 (setq p1 (vlax-curve-getpointatdist e1 idx))                 (setq p2 (vlax-curve-getclosestpointto e2 p1))            )       (setq dis (distance p1 p2)             idx  (+ idx step)       )       (if (or (null dlst) (< dis (car dlst)))         (setq dlst (list dis p1 p2))       )                   )          (if (and dlst (listp dlst))       (progn         (setq dlst (2ObjDist e1 e2 (cadr dlst))               dis (car dlst))         (grdraw (trans (cadr dlst)0 1)(trans (caddr dlst)0 1) 6 1)       )     )    )  )  (print dis)  (princ))(prompt "\nMinimum Distance Loaded, Enter MD to run.")(princ)`
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 23, 2008, 02:34:28 PM
Alan i added some things to your code, hope you don't mind :)
Code: [Select]
`(defun c:MinDist (/ step e1 e2 p1 p2 len idx dis dlst curveOK getent hasb e3)  (vl-load-com)  ;;  CAB test to see if vlax-curve can be used on an object  (defun curveOK (ent)   ; returns nil if not allowed    (not (vl-catch-all-error-p    (vl-catch-all-apply 'vlax-curve-getendparam (list ent)) )    )  )  ;; returns an entity which can be used with vlax-curve  (defun getent (pmt / ent)    (while (not (and (setq ent (car (entsel pmt))) (curveOK ent)))      (prompt "\nMissed or not a Curve object. Try again.")    )    ent  )  ;;  get the min distance between 2 objects nearest to pt  ;;  pt should be a point on obj1  (defun 2ObjDist (e1 e2 p1 / p2 d fuzz)    (setq fuzz 1E-8)    (while (not      (minusp        (- (distance p1 (setq p2 (vlax-curve-GetClosestPointTo e2 p1)))   (setq d (distance p2 (setq p1 (vlax-curve-GetClosestPointTo e1 p2))))   fuzz        )      )    )    )    (list d p1 p2)  )  (defun NoBulgeDist (e1 e2 / p1 p2 i d)    (setq i (vlax-curve-getEndParam e1))    (while (and (>= i 0))      (setq p2 (vlax-curve-getClosestPointTo    e2    (setq p1 (vlax-curve-getPointAtParam e1 i)) )     hasb (or hasb (not (equal (vlax-curve-getSecondDeriv e1 i) '(0 0 0))))     i (1- i)     d (distance p1 p2)     dlst (if (or (< d (car dlst)) (null dlst))    (list d p1 p2)    dlst )      )    )  )  ;;=========================================================  (setq e1 (getent "\nFirst entity: "))  (setq e2 (getent "\nSecond entity: "))  (if (vlax-invoke (vlax-ename->vla-object e1) 'IntersectWith (vlax-ename->vla-object e2) acExtendNone      )    (setq dis 0.0)    (progn (NoBulgeDist e2 e1)    (setq dlst (cons (car dlst) (reverse (cdr dlst))))    (NoBulgeDist e1 e2)    (if hasb      (progn (if (> (vlax-curve-getDistAtParam e1 (vlax-curve-getEndParam e1))    (vlax-curve-getDistAtParam e2 (vlax-curve-getEndParam e2)) )       (setq e3 e1     e1 e2     e2 e3     dlst (cons (car dlst) (reverse (cdr dlst)))       )     )     ;| find the min distance within the steps. The accuracy is limited by the    number of steps, then 2ObjDist is used to increase the accuracy|;     (setq idx  0.0   len  (vlax-curve-getdistatparam e1 (vlax-curve-getendparam e1))   step (/ len 1000)   ; 100 may need to increase for very large unit objects     )     (while (and (<= idx len) (setq p1 (vlax-curve-getpointatdist e1 idx)))       (setq p2 (vlax-curve-getclosestpointto e2 p1)     dis (distance p1 p2)     idx (+ idx step)       )       (if (< dis (car dlst)) (setq dlst (list dis p1 p2))       )     )      )    )    (setq dlst (2ObjDist e1 e2 (cadr dlst)))    (setq dis (car dlst))    (grdraw (trans (cadr dlst) 0 1) (trans (caddr dlst) 0 1) 6 1)    )  )  (print dis)  (princ))`
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 28, 2008, 08:30:28 AM
My bells and whistles version attached. Check the header comments.

With thanks to Alan and VovKa.  :-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 28, 2008, 11:44:30 AM
Here is my contribution...will prompt if objects except *polylines (no time right now to address) are parallel.

Code: [Select]
`... ;;Adds distances gathered into dlst then divides by (1+ div) ;;to check if equal (+- 0.001) to middle item in list. Still need to ;;create function to account for polylines as well (if (and (equal on1 on2) (not (wcmatch on1 "*Polyline")) (not (wcmatch on2 "*Polyline")) (equal (/ (apply '+ dlst) (1+ div)) (nth (/ (length dlst) 2) dlst) 0.001 )     )   (setq m (strcat "\n(" (substr on1 5) "'s appear to be parallel)"))   (setq m "") )...`
Ron
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 28, 2008, 12:27:02 PM
hi Joe
may i suggest 2 things that you've missed in my last post :pissed:  :-)
http://www.theswamp.org/index.php?topic=23170.msg280044#msg280044 (http://www.theswamp.org/index.php?topic=23170.msg280044#msg280044)

if two polylines are selected it would be better to run NoBulgeDist on them, and if they do not have bulges we will have the desired distance right away (much faster)

we will get the desired distance faster if we step along the shortest of two selected objects
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 29, 2008, 05:48:57 AM
Hi VovKa,

I ran speed tests while working on the latest code. They indicated the
core part of the routine, from IntersectWith to where the two points are
known, was already fast. Like 0.1 second or less and often half that.
This includes cases where the second calculation, the part you rewrote,
gets a good workout.

At that point I thought, rightly or wrongly, trying to make it faster
wasn't worth it. I'm sure you're right, it could be faster. I wonder
though whether the user would ever see the difference.

There could be a condition which tests for whether either objects is a
circle. Special case since there are no ends to deal with. Get the closest
point on the other object from center point of the circle. Get the closest
point on the circle from that point.

I found something interesting while speed testing. Check the attached
example file and the test routine which follows. The polylines have more
than 600 vertices, no bulges I believe. The IntersectWith method takes
about 0.35 second to compare the objects. It causes a noticeable lag in
the routine.

Code: [Select]
`(defun StartTimer ()  (setq *start* (getvar "date")))(defun EndTimer (/ end)  (setq end (* 86400 (- (getvar "date") *start*)))  (princ (strcat "\nTimer: " (rtos end 2 8) " seconds\n")))(defun c:test ( / obj1 obj2)  (setq obj1 (car (entsel "\nSelect polyline: "))        obj1 (vlax-ename->vla-object obj1)        obj2 (car (entsel "\nSelect polyline: "))        obj2 (vlax-ename->vla-object obj2)  )  (starttimer)  (vlax-invoke obj1 'IntersectWith obj2 acExtendNone)  (endtimer))`
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 29, 2008, 06:29:16 AM
Quote

we will get the desired distance faster if we step along the shortest of two selected objects

Do you mean faster because the test points along the shorter object are spaced closer together? And that may mean fewer iterations during the second calculation?
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 29, 2008, 07:14:30 AM
Here is my contribution...will prompt if objects except *polylines (no time right now to address) are parallel.

Interesting idea. It would be nice to eliminate these two sub-functions, MD:NormalAngle and MD:ParallelLines, which only serve a limited purpose.
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 29, 2008, 02:07:56 PM
Quote
Do you mean faster because the test points along the shorter object are spaced closer together? And that may mean fewer iterations during the second calculation?
i think in most cases it will be true
as for IntersectWith... it's doing 645*621 (inters)es, or whatever it's programmed to do, maybe it has to be slow :)
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 29, 2008, 04:34:00 PM
Here is my contribution...will prompt if objects except *polylines (no time right now to address) are parallel.

Interesting idea. It would be nice to eliminate these two sub-functions, MD:NormalAngle and MD:ParallelLines, which only serve a limited purpose.

Done....I also changed the code a bit to compare the averaged distance to the midpoint distance. My previous function would fail if one object was longer than the other.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 30, 2008, 05:45:18 AM
Quote
Done....I also changed the code a bit to compare the averaged distance to the midpoint distance. My previous function would fail if one object was longer than the other.

I'm confused. Did you update the code posted before, or did you intend to post a new version?
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 30, 2008, 08:44:05 AM
I added the following condition before the T condition. It uses the center of a circle as test point if one of the two objects is a circle.

AFAIK it's reliable and as expected it reduces the core function elapsed time to zero. On average it saves about 0.05 second. Obviously not worth the effort.

At the risk of repeating myself, though one method may prove faster than another, that does not always translate to a meaningful improvement. I would leave the code as is.

Code: [Select]
`((setq pos (vl-position "AcDbCircle" (list typ1 typ2)))  (if (zerop pos)    (setq testpt (vlax-get obj1 'Center))    (setq testpt (vlax-get obj2 'Center))  )  (if (not (zerop pos))    ;; Reverse the objects.    (setq temp obj1 obj1 obj2 obj2 temp)  )  (setq p1 (vlax-curve-GetClosestPointTo obj2 testpt)        pt (vlax-curve-GetClosestPointTo obj1 p1)        d (distance pt p1)        resdist d  ))`
One other thought. If anyone wants to post a new version it should be labeled as beta until others have a chance to test it.

Regards
Joe
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 30, 2008, 10:20:34 AM
Quote
Done....I also changed the code a bit to compare the averaged distance to the midpoint distance. My previous function would fail if one object was longer than the other.

I'm confused. Did you update the code posted before, or did you intend to post a new version?

I updated the code here:

http://www.theswamp.org/index.php?topic=23170.msg280827#msg280827
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 30, 2008, 01:20:24 PM
I tried your code. Sorry, but I doubt it will work.

Attached is an example. When I run your code and select the two lines it reprorts they are parallel, when obviously they are not.

This appoach is a dead-end because parallel is essentially an angular function. Trying to compare points to determine parallel is full of pitfalls.
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 30, 2008, 01:33:23 PM
who cares about paralellness? :)
we are looking for minimum distance ie. two closest points... imho
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on May 30, 2008, 02:39:21 PM
who cares about paralellness? :)
we are looking for minimum distance ie. two closest points... imho

I care because there were two driving forces behind the idea. The first one was godzilla Tony saying it can't be done. And the second one was a practical application of the idea which may not be readily apparent.

I'm often given CAD files drawn by someone other than myself. I want a quick way to check accuracy. For example, a structural grid file which is already dimensioned. I want to check the actual distance between lines agrees the dimensions. For that to make sense I also need to know if the line are parallel.

Think ouside the box. This routine is designed to do more than its apparent intent. As anyone who has used Microstation would know.
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 30, 2008, 03:28:30 PM
who cares about paralellness? :)
we are looking for minimum distance ie. two closest points... imho

I don't really care about parallel lines....just thought it would be fun to write :-P
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on May 30, 2008, 03:32:57 PM
I tried your code. Sorry, but I doubt it will work.

Attached is an example. When I run your code and select the two lines it reprorts they are parallel, when obviously they are not.

This appoach is a dead-end because parallel is essentially an angular function. Trying to compare points to determine parallel is full of pitfalls.

you're right Joe....I'll quit while I'm ahead
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 30, 2008, 03:57:07 PM
when talking of lines why not just use
Code: [Select]
`(not (vlax-invoke obj1 'IntersectWith obj2 acExtendBoth))`to know if they are paralell?
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 30, 2008, 04:11:13 PM
Lines Green & Yellow are not parallel & do not intersect. Think 3D 8-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: daron on May 30, 2008, 04:12:21 PM
??? Are they also non-coplanar?
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 30, 2008, 05:53:12 PM
Lines Green & Yellow are not parallel & do not intersect. Think 3D 8-)
you are killing me :)
Code: [Select]
`(defun Paral3D (obj1 obj2 / a1 a2 acos)  (setq a1   (vlax-curve-getFirstDeriv obj1 0) a2   (vlax-curve-getFirstDeriv obj2 0) acos (/ (apply '+ (mapcar '* a1 a2)) (* (sqrt (apply '+ (mapcar 'expt a1 '(2 2 2))))    (sqrt (apply '+ (mapcar 'expt a2 '(2 2 2)))) )      )  )  (zerop (atan (/ (sqrt (- 1. (* acos acos))) acos))))`
Title: Re: Minimum distance between two vlax-curve objects
Post by: Kerry on May 30, 2008, 07:30:58 PM
Lines Green & Yellow are not parallel & do not intersect. Think 3D 8-)
you are killing me :)
< .. >
:-D

that's Alan's job   :-)

really interesting code guys .. nice to read
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 30, 2008, 09:59:49 PM
:-)
Code: [Select]
`;;  check for parallel entities CAB  11/04/06(defun parallel (e1 e2 pfuzz)  ;;  rem reduces angles > pi so range is 0 - 180 deg  (if (and (vlax-property-available-p (vlax-ename->vla-object e1) 'angle)           (vlax-property-available-p (vlax-ename->vla-object e2) 'angle))    (equal (rem (vla-get-angle (vlax-ename->vla-object e1)) pi)         (rem (vla-get-angle (vlax-ename->vla-object e2)) pi)     pfuzz)  ))`
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on May 30, 2008, 10:03:30 PM
Lines Green & Yellow are not parallel & do not intersect. Think 3D 8-)
you are killing me :)
Code: [Select]
`(defun Paral3D (obj1 obj2 / a1 a2 acos)  (setq a1   (vlax-curve-getFirstDeriv obj1 0) a2   (vlax-curve-getFirstDeriv obj2 0) acos (/ (apply '+ (mapcar '* a1 a2)) (* (sqrt (apply '+ (mapcar 'expt a1 '(2 2 2))))    (sqrt (apply '+ (mapcar 'expt a2 '(2 2 2)))) )      )  )  (zerop (atan (/ (sqrt (- 1. (* acos acos))) acos))))`
That's some fancy math there VovKa. I like it.  8-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: VovKa on May 31, 2008, 05:45:25 AM
Quote
That's some fancy math there VovKa. I like it.
vector algebra, i feel like going back to school :)
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 02, 2008, 08:30:47 AM
Attached is an example file which demonstrates something I've run into while testing for parallel lines. A zero angle line after two rotations may report its angle as (* pi 2).

If the angle of the copied line is fed to the NormalAngle function contained in MinDist it will return 0.0.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 02, 2008, 10:52:26 AM
Code: [Select]
`(defun Paral3D (obj1 obj2 / a1 a2 acos)  (setq a1   (vlax-curve-getFirstDeriv obj1 0) a2   (vlax-curve-getFirstDeriv obj2 0) acos (/ (apply '+ (mapcar '* a1 a2)) (* (sqrt (apply '+ (mapcar 'expt a1 '(2 2 2))))    (sqrt (apply '+ (mapcar 'expt a2 '(2 2 2)))) )      )  )  (zerop (atan (/ (sqrt (- 1. (* acos acos))) acos))))`
Alan,

While this is interesting, do you think there's any reason to revise MinDist 1.0 to use it?

I think not assuming it is only testing for parallel lines.
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on June 02, 2008, 11:40:15 AM
I see no reason to change your code.  :-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 06, 2008, 10:48:06 AM
I'm working on a version which allows selection of objects within blocks or xrefs at any nested depth.

Mostly done, but still a few kinks to work out.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 08, 2008, 09:57:59 AM
Here's the version mentioned above named MinDist 1.3 beta. Works with objects nested in blocks or xrefs.

See the header comments for a full explanation of what's going on.

I thiink this makes the routine much more useful. Hope you agree. :-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 10, 2008, 08:54:40 AM
As is the routine will toss an error if a non-uniformly scaled block is involved. I'm working on error checking for that condition.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 11, 2008, 08:13:43 AM
Version 1.4 beta. Added error checking for non-uniformly scaled blocks.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 24, 2008, 07:09:47 AM
Minor bug fix version named MinDist 1.4a attached. See the header comments for version history.
Title: Re: Minimum distance between two vlax-curve objects
Post by: CAB on June 24, 2008, 08:12:16 AM
Thanks Joe.
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 24, 2008, 09:14:10 AM
Alan,

Thanks for your help with the code.
Title: Re: Minimum distance between two vlax-curve objects
Post by: ronjonp on June 24, 2008, 09:49:51 AM
Nice job Joe  :-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on June 25, 2008, 08:10:02 AM
Thanks, ronjonp.  :-)
Title: Re: Minimum distance between two vlax-curve objects
Post by: mikeg on July 02, 2008, 02:40:34 PM
Wow this code works great! Mind i use it guys that worked on it?
Title: Re: Minimum distance between two vlax-curve objects
Post by: Joe Burke on July 04, 2008, 06:25:20 AM
Wow this code works great! Mind i use it guys that worked on it?

Glad to hear you like it. Use as you wish.

Updated version attached. Added support for object types point, ray and xline. Also works with objects nested in dimensions.
Title: Re: Minimum distance between two vlax-curve objects
Post by: chlh_jd on January 02, 2012, 09:30:22 AM
Happy New Year to All .
Hi Joe , just read your works , Good job .
However , I guess it can be get by higher Accuracy , I post my poor codes , I hope you don't mind . :-)
Code: [Select]
`(defun c:test       (/ en1 e en2 fuzz l1 l2 lim l0 d0 p0        p)  ;;by GSLS(SS) 2012.1.2  (defun getlength (e)    (vlax-curve-getDistAtPoint      e      (vlax-curve-getendpoint e)    )  )  (defun f0 (a b / mid rslt)    (repeat (/ (length a) b)      (setq mid nil)      (repeat b (setq mid (cons (car a) mid)       a   (cdr a) )      )      (setq rslt (cons (reverse mid) rslt))    )    (if a      (reverse (cons a rslt))      (reverse rslt)    )  )  (defun f1 (e p)    (distance p (vlax-curve-getClosestPointTo e p))  )  (defun f2 (e1 e2 p lim / l0 d0 p0 l)    (setq l0 (vlax-curve-getDistAtPoint e1 p)   d0 (f1 e2 p)   p0 p   l  l0    )    (repeat 10      (setq l (- l lim))      (if (and (>= l 0) (setq p (vlax-curve-getpointatdist e1 l))) (if (and (setq d (f1 e2 p)) (< d d0)     )   (setq d0 d p0 p   ) )      )    )    (setq l l0)    (repeat 10      (setq l (+ l lim))      (if (and (>= l 0) (setq p (vlax-curve-getpointatdist e1 l))) (if (and (setq d (f1 e2 p)) (< d d0)     )   (setq d0 d p0 p   ) )      )    )    p0  )  (defun f3 (e1 e2 lim / mid)    (if (not   (minusp     (vlax-safearray-get-u-bound       (vlax-variant-value (setq mid (vla-IntersectWith     (vlax-ename->vla-object e1)     (vlax-ename->vla-object e2)     lim   ) )       )       1     )   ) )      (list-comp (vlax-safearray->list (vlax-variant-value mid)) 3      )    )  )  (setq en1 (car (ss-Nentsel "\nSelect First Curve :")) en2 (car (ss-Nentsel "\nSelect Second Curve :"))  )  (setq fuzz (getreal "\nType in Accuracy <1e-6> :"))  (or fuzz (setq fuzz 1e-6))  (if (and en1 en2)    (if (f3 en1 en2 0)      (princ "\nThe 2 Curves is intersectwithed !")      (progn (setq l1 (getlength en1)       l2 (getlength en2) ) (if (< l2 l1)     (setq e   en1 en1 en2 en2 e l1  l2   ) ) (setq lim (/ l1 (1+ (fix (/ l1 200.))))       l0  0.       d0  1e308 ) (repeat (fix (/ l1 lim))   (setq p (vlax-curve-getpointatdist en1 l0))   (setq d (f1 en2 p))   (if (< d d0)     (setq d0 d   p0 p     )   )   (setq l0 (+ l0 lim)) ) (setq is_go T) (while (and (> lim fuzz) is_go)   (setq p (f2 en1 en2 p0 (setq lim (/ lim 10.))))   (if (equal p p0 fuzz)     (setq is_go nil   p0 p     )     (setq p0 p)   ) ) (setq p (vlax-curve-getClosestPointTo en2 p0)) (entmakex (list (cons 0 "LINE") (cons 8 "Defpoints") (cons 10 p0) (cons 11 p) (cons 62 1)   ) )      )    )  )  (princ))(defun ss-Nentsel (msg / en en1 pt mat ins mat ent )  (setq en (Nentsel msg))  (if (= (length en) 4)    (progn      (setq en1   (car en)     pt    (cadr en)     mat   (caddr en)     ins   (last mat)     mat   (butlast mat)         mat  (ss-getrcsmatrix mat ins)      )      (setq ent (entget en1 (list "*")))      (setq ent (vl-remove (assoc -1 ent) ent))      (setq en1 (entmakex ent))      (if en1 (progn   (setq obj (en2obj en1))   (vla-TransformBy obj (vlax-tmatrix mat))   (setq en1 (obj2en obj)) )      )      (list en1 pt T)    )    (append en (list nil))  ));;; BY GSLS(SS);;; 2010-09-29(defun ss-getrcsmatrix (lst org)  (append    (mapcar (function (lambda (x y)        (append x (list y))      ))     lst     org    )    (list (list 0. 0. 0. 1.))  ))`