TheSwamp

Code Red => AutoLISP (Vanilla / Visual) => Topic started by: Didge on February 22, 2006, 09:57:39 AM

Title: Getpoint Precision.
Post by: Didge on February 22, 2006, 09:57:39 AM
I feel pretty stupid for asking this, I suspect this'll lead to one of those "DOH!!-slap head" moments.

Anyway, I have a Map3D 2006 dwg that refuses to return accurate (getpoint) coords.  It does it's thing as usual but rounds the returned coords up or down to the nearest unit.  It appears to be 'dwg' specific so Im guessing it's a system variable issue.

I've checked through the usual tweaks such as  Dimzin, Lunits, luprec, Unitmode, -dwgunits  but no joy. 

Am I missing something blindingly obvious? :oops:

I forgot to mention, everything seems to work fine in paper space.
Title: Re: Getpoint Precision.
Post by: LE on February 22, 2006, 10:10:58 AM
Are you simple calling something like:

Code: [Select]
(setq pt (getpoint "\nPick a point: "))

?

I do not have A2006.
Title: Re: Getpoint Precision.
Post by: CAB on February 22, 2006, 10:15:48 AM
See if this helps.
http://www.theswamp.org/forum/index.php?topic=1962.msg25629#msg25629
Title: Re: Getpoint Precision.
Post by: Didge on February 22, 2006, 10:40:05 AM
Nothing as extravagent as that LE, just a solitary  (getpoint)  in model space.

Thanks CAB, but nothing in that thread seems to help in this case.

I've attached a 2000 version of the 'dwg' in question, no objects, just an empty dwg.
Title: Re: Getpoint Precision.
Post by: LE on February 22, 2006, 10:54:18 AM
I tested your drawing... and...
It might be my eyes... but seems that getpoint is returning the right output....
Title: Re: Getpoint Precision.
Post by: CAB on February 22, 2006, 10:55:57 AM
Well the get point returns an accurate number but does not display it.

Code: [Select]
Command: (setq a (getpoint))
(586922.0 191777.0 0.0)

Command: !a
(586922.0 191777.0 0.0)

Command: (- (car a) 586922.0)
0.187917
You see the fraction is there.
That is the nature of ACAD when the numbers get that large.
Title: Re: Getpoint Precision.
Post by: LE on February 22, 2006, 11:02:48 AM
What are you doing with those points?

One way to get more precision is to use:

(setq pt (getpoint "\nPoint: "))
(rtos (car pt) 2 16)
(rtos (cadr pt) 2 16)
(rtos (caddr pt) 2 16)
Title: Re: Getpoint Precision.
Post by: ronjonp on February 22, 2006, 11:06:29 AM
LE,

Funny you post that...I just put this together:

Code: [Select]
(setq pt (getpoint "\nPick a point: ")
       x (rtos (car pt)2 15)
       y (rtos (cadr pt)2 15)
       z (rtos (caddr pt)2 15)
      pt (list x y z)
)
How would the list be converted back to a usable point and keep the precision?

Ron
Title: Re: Getpoint Precision.
Post by: T.Willey on February 22, 2006, 11:10:12 AM
I have found that the precision is always there, it just doesn't always display right.  What they are showing is a way to SEE it correctly.
Title: Re: Getpoint Precision.
Post by: CAB on February 22, 2006, 11:28:24 AM
Quote
Reals
A real is a number containing a decimal point. Numbers between –1 and 1
must contain a leading zero. Real numbers are stored in double-precision
floating-point format, providing at least 14 significant digits of precision
Note that VLISP does not show you all the significant digits.
Reals can be expressed in scientific notation, which has an optional e or E followed
by the exponent of the number (for example, 0.0000041 is the same
as 4.1e-6). Numbers such as 3.1, 0.23, –56.123, and 21,000,000.0 are valid
AutoLISP reals.
Title: Re: Getpoint Precision.
Post by: LE on February 22, 2006, 11:30:30 AM
^
What CAB... found too....
Title: Re: Getpoint Precision.
Post by: CAB on February 22, 2006, 11:45:38 AM
Also read this thread.
http://tinyurl.com/nbzue
Title: Re: Getpoint Precision.
Post by: Didge on February 22, 2006, 11:45:55 AM
The following demonstrates the problem, (not sure how to post an image here)
Notice how 'ID' and 'Getpoint' return different values for the same point. Maybe this is a Map3D issue I'm unfamiliar with.

LINE Specify first point:
Specify next point or [Undo]:
Specify next point or [Undo]:

Command: id
Specify point: _endp of  X = 15024.689     Y = -127900.431     Z = 0.000

Command: (getpoint)
_endp of (15024.7 -127900.0 0.0)
Title: Re: Getpoint Precision.
Post by: T.Willey on February 22, 2006, 11:48:11 AM
Try this.
Code: [Select]
(foreach i (getpoint)
 (princ (strcat "\n " (rtos i 2 4)))
)
Title: Re: Getpoint Precision.
Post by: LE on February 22, 2006, 11:52:19 AM
Quote from: LE on February 22, 2006, 11:02:48 AM
What are you doing with those points?

Update me....  :whistle:
Title: Re: Getpoint Precision.
Post by: Didge on February 22, 2006, 12:27:38 PM
I was completing some code to automatically generate pipeline longsections by picking a 2d polyline drawn above a TIN (see 'triangulation' thread) when I noticed the issue. The coding seems to work well, but I can't remember getpoint ever rounding display co-ordinates before.

CAB appears to be correct in that acad is retaining the decimals but displaying them rounded, this gives me peace of mind in my calculations, but it still doesn't explain whats forcing the rounding.

If I start a new drawing all seems fine again, so I still suspect a system variable at the heart of things.
Title: Re: Getpoint Precision.
Post by: CAB on February 22, 2006, 12:50:53 PM
The number displayed by getpoint will round more as you move away form 0,0
In the NEW drawing, are you near 0,0 ?
Title: Re: Getpoint Precision.
Post by: Didge on February 22, 2006, 01:29:55 PM
As predicted "DOH !!" - <slaps head>  Guess who feels stupid now?

Yes that was it CAB, the rounding is indeed relative to the origin, in all my years of coding I've never noticed this before.

If this place wasnt virtual I'd buy you guys a beer.

Thank-you all for your assistance, I will be able to sleep tonight, albeit while wearing my stupid hat   :oops: