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Replies:
22
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Last Post:
Feb 1, 2009 1:20 PM
Last Post By: Joe Burke
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Posts:
24
Registered:
01/22/09
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Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:00 PM
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I am trying to set a point as the midpoint between two (Getpoints..) Everything I think of is way too lengthy, is there a shortway to find this?
(setq pt1 (getpoint "\nPick LEFT point:")
pt2 (getpoint "\nPick RIGHT point:")
pt3 (...
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:12 PM
in response to: structure_fire3
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you could draw a line between the two points, get
the mid point of the line then erase the line
I
am trying to set a point as the midpoint between two (Getpoints..) Everything
I think of is way too lengthy, is there a shortway to find this? (setq pt1
(getpoint "\nPick LEFT point:") pt2 (getpoint "\nPick RIGHT point:") pt3
(...
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Posts:
727
Registered:
08/08/06
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:14 PM
in response to: structure_fire3
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(setq pt1 (getpoint "\nPick LEFT point:")
pt2 (getpoint "\nPick RIGHT point:")
x (/ (+ (car pt1) (car pt2)) 2)
y (/ (+ (cadr pt1) (cadr pt2)) 2)
z (/ (+ (caddr pt1) (caddr pt2)) 2)
pt3 (list x y z)
)
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Posts:
24
Registered:
01/22/09
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:21 PM
in response to: lpseifert
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Thanks, thats exactly what i was looking for.
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:16 PM
in response to: structure_fire3
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One way: (setq midpt(polar p1(angle p1 p2)(/(distance p1 p2)2)))
Alternatively: (setq midpt(mapcar '* (mapcar '+ p1 p2) '(0.5 0.5 0.5)))
Regards,
Mel
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:29 PM
in response to: MelFranks
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< (setq midpt (mapcar '* (mapcar '+ p1 p2) '(0.5 0.5 0.5)))>
Now, this is elegant and slick :)
Regards
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Posts:
24
Registered:
01/22/09
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:35 PM
in response to: Some Buddy
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Thanks, worked like a charm. That was slick. =)
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:42 PM
in response to: MelFranks
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MelFranks wrote:
One way: (setq midpt(polar p1(angle p1 p2)(/(distance p1 p2)2)))
Alternatively: (setq midpt(mapcar '* (mapcar '+ p1 p2) '(0.5 0.5 0.5)))
Regards,
Mel
These are about as compact as you can get. Note that when using points p1 and p2 with different Z-coordinates, the (polar) approach above returns a point whose Z-coordinate is equal to that of p1, while the (mapcar) approach returns a point whose Z-coordinate is half-way between those of p1 and p2. |
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 6:48 PM
in response to: Bill Gilliss
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Good point you have here, Bill. Afterall, the
world's not flat and of course Mel knows it, but it was just answered in a blink
:)
MelFranks wrote: One way: (setq midpt(polar p1(angle p1 p2)(/(distance p1 p2)2)))
Alternatively: (setq midpt(mapcar '* (mapcar '+ p1 p2) '(0.5 0.5 0.5)))
Regards,
Mel
These are about as compact as you can get. Note that when using points p1 and p2 with different Z-coordinates, the (polar) approach above returns a point whose Z-coordinate is equal to that of p1, while the (mapcar) approach returns a point whose Z-coordinate is half-way between those of p1 and p2.
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 7:06 PM
in response to: MelFranks
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Or, other-alternatively [same effect, but just slightly shorter]:
(setq midpt (mapcar '/ (mapcar '+ p1 p2) '(2 2 2)))
--
Kent Cooper
"MelFranks" wrote...
....
Alternatively: (setq midpt(mapcar '* (mapcar '+ p1 p2) '(0.5 0.5 0.5)))
....
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 10:14 PM
in response to: Kent Cooper
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Kent Cooper wrote:
Or, other-alternatively [same effect, but just slightly shorter]:
(setq midpt (mapcar '/ (mapcar '+ p1 p2) '(2 2 2)))
Shorter yet, in terms of characters: (setq midpt (c:cal
"(p1+p1)/2"))
unless you count the required initial (arxload "geomcal").
The meaning is perfectly clear, too. -Bill |
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Re: Midpoint between two Getpoints?
Posted:
Jan 27, 2009 10:40 PM
in response to: Bill Gilliss
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You mean (setq midpt (c:cal "(p1+p2)/2")), but it's been a long day :) Yes, this one of yours is really
shorter, in terms of functions calls or otherwise I can do a shorter one too: (setq mp (c:cal "(p1+p2)*.5")) ;^) And let's assume that the arx is loaded, Or
at least, DEMANDLOAD is set to 2 or 3. Regards
Kent Cooper wrote: Or, other-alternatively [same effect, but just slightly shorter]:
(setq midpt (mapcar '/ (mapcar '+ p1 p2) '(2 2 2))) Shorter yet, in terms of characters: (setq midpt (c:cal
"(p1+p1)/2"))
unless you count the required initial (arxload
"geomcal").
The meaning is perfectly clear, too. -Bill
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 12:34 AM
in response to: Some Buddy
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Some Buddy wrote:
You mean (setq midpt (c:cal "(p1+p2)/2")), but it's been a long day :) Yes, this one of yours is
really shorter, in terms of functions calls or otherwise I can do a shorter one too: (setq mp (c:cal "(p1+p2)*.5"))
You got me on the (p1+p1). But /2 is still shorter than *.5While we are at it, let's get rid of all spaces and both earlier (getpoint) functions with
(set'm(c:cal"(cur+cur)/2"))
27 characters.
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 12:55 PM
in response to: Bill Gilliss
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Bill
IMO, calling cal is not a good idea since it is not loaded by default.
I would use a LISP function similar to what Kent suggested.
Joe Burke
"Bill Gilliss" wrote in message
news:6113023@discussion.autodesk.com...
Some Buddy wrote:
You mean (setq midpt (c:cal "(p1+p2)/2")), but it's been a long day :)
Yes, this one of yours is really shorter, in terms of functions calls or otherwise I
can do a shorter one too:
(setq mp (c:cal "(p1+p2)*.5"))
You got me on the (p1+p1).
But /2 is still shorter than *.5
While we are at it, let's get rid of all spaces and both earlier (getpoint) functions
with
(set'm(c:cal"(cur+cur)/2"))
27 characters.
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 2:22 PM
in response to: Joe Burke
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Yeah, yeah - we agreed in an earlier post that geomcal would need to be loaded, just as (vl-load-com) must be. This was just a little contest to find the most compact midpoint routine once such preliminaries were taken care of. Joe Burke wrote: Bill
IMO, calling cal is not a good idea since it is not loaded by default.
I would use a LISP function similar to what Kent suggested.
Joe Burke |
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 2:43 PM
in response to: Bill Gilliss
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Bill, I stand by my statement. Cal and the time to first load it simply isn't needed. It's not a good idea since the goal can be met with a simple LISP function as Kent suggested. "Bill Gilliss" wrote in message news:6113238@discussion.autodesk.com... Yeah, yeah - we agreed in an earlier post that geomcal would need to be loaded, just as (vl-load-com) must be. This was just a little contest to find the most compact midpoint routine once such preliminaries were taken care of. Joe Burke wrote: Bill
IMO, calling cal is not a good idea since it is not loaded by default.
I would use a LISP function similar to what Kent suggested.
Joe Burke |
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 1:49 PM
in response to: Bill Gilliss
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 2:27 PM
in response to: Some Buddy
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Well, to take it perhaps to the extreme, if one *really* wanted to minimize the total amount of
code, and if this is something used within many different routines, one could put a function in a
place where it would be available in any drawing, such as in acaddoc.lsp:
(defun midway (p1 p2)
(mapcar '/ (mapcar '+ p1 p2) '(2 2 2)); or other approach
)
and then just call that function within each of the various routines:
(midway pt1 pt2)
as some do with functions like (dtr) [degrees-to-radians conversion], etc.
--
Kent Cooper
"Some Buddy" wrote...
OK, you win :)
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 2:51 PM
in response to: Kent Cooper
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Also keep in mind the M2P and MTP commands which are available in recent versions at
any getpoint prompt.
"Kent Cooper" wrote in message
news:6113211@discussion.autodesk.com...
Well, to take it perhaps to the extreme, if one *really* wanted to minimize the total
amount of
code, and if this is something used within many different routines, one could put a
function in a
place where it would be available in any drawing, such as in acaddoc.lsp:
(defun midway (p1 p2)
(mapcar '/ (mapcar '+ p1 p2) '(2 2 2)); or other approach
)
and then just call that function within each of the various routines:
(midway pt1 pt2)
as some do with functions like (dtr) [degrees-to-radians conversion], etc.
--
Kent Cooper
"Some Buddy" wrote...
OK, you win :)
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 3:02 PM
in response to: Joe Burke
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Wish I had a more "recent version" than I do, sometimes....
--
Kent Cooper
"Joe Burke" wrote...
Also keep in mind the M2P and MTP commands which are available in recent versions at
any getpoint prompt.
....
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 3:13 PM
in response to: Kent Cooper
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Doh!
(setq c"mtp"a b)
16 characters, including spaces. I think Joe wins, even if he
wasn't playing.
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Re: Midpoint between two Getpoints?
Posted:
Feb 1, 2009 1:20 PM
in response to: Kent Cooper
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Hi Kent,
I think the M2P and MTP commands were added at 2005.
Joe
"Kent Cooper" wrote in message
news:6113273@discussion.autodesk.com...
Wish I had a more "recent version" than I do, sometimes....
--
Kent Cooper
"Joe Burke" wrote...
Also keep in mind the M2P and MTP commands which are available in recent versions at
any getpoint prompt.
....
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Posts:
120
Registered:
09/22/08
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Re: Midpoint between two Getpoints?
Posted:
Jan 28, 2009 1:00 AM
in response to: structure_fire3
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My favourite: (mapcar '/ (mapcar '+ p1 p2) (list 2.0 2.0 2.0))
Alternate : (mapcar '(lambda (x y) (/ (+ x y) 2.0)) p1 p2)
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