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Constant line thickness after scale

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  Constant line thickness after scale Cecil Westerhof <Cecil@decebal.nl> - 2014-09-03 19:50 +0200
    Re: Constant line thickness after scale abeddie <abeddie@hotmail.com> - 2014-09-03 11:26 -0700
      Re: Constant line thickness after scale Mark Carroll <mtbc@bcs.org> - 2014-09-03 19:35 +0100
      Re: Constant line thickness after scale Cecil Westerhof <Cecil@decebal.nl> - 2014-09-04 10:42 +0200
        Re: Constant line thickness after scale ken <ken@spamcop.net> - 2014-09-04 10:16 +0100
    Re: Constant line thickness after scale Mark Carroll <mtbc@bcs.org> - 2014-09-03 19:34 +0100
    Re: Constant line thickness after scale tlvp <mPiOsUcB.EtLlLvEp@att.net> - 2014-09-03 20:46 -0400

#2007 — Constant line thickness after scale

With the following code I can draw an ellipse:
    25  dup  translate
     2  setlinewidth
     4  1  scale
     0  dup  4  0  360  arc   closepath   stroke
    showpage

But at east and west the line thickness is bigger as at north and
south. Is it possible to draw an ellipse which has a constant line
thickness?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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#2008

On Wednesday, September 3, 2014 2:09:23 PM UTC-4, Cecil Westerhof wrote:
> With the following code I can draw an ellipse:
> 
>     25  dup  translate
> 
>      2  setlinewidth
> 
>      4  1  scale
> 
>      0  dup  4  0  360  arc   closepath   stroke
> 
>     showpage
> 
> 
> 
> But at east and west the line thickness is bigger as at north and
> 
> south. Is it possible to draw an ellipse which has a constant line
> 
> thickness?
> 
> 
> 
> -- 
> 
> Cecil Westerhof
> 
> Senior Software Engineer
> 
> LinkedIn: http://www.linkedin.com/in/cecilwesterhof

Reverse the scale before calling stroke:

0  dup  4  0  360  arc   closepath   .25 1 scale stroke

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#2010

abeddie <abeddie@hotmail.com> writes:

> Reverse the scale before calling stroke:
>
> 0  dup  4  0  360  arc   closepath   .25 1 scale stroke

That's really neat, I had never seen that: scaling the line's path
without actually affecting the stroked line like that. I wonder where
else I should have used this but didn't know to.

-- Mark

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#2013

Op Wednesday 3 Sep 2014 20:26 CEST schreef abeddie@hotmail.com:

> On Wednesday, September 3, 2014 2:09:23 PM UTC-4, Cecil Westerhof wrote:
>> With the following code I can draw an ellipse:
>>
>> 25  dup  translate
>>
>> 2  setlinewidth
>>
>> 4  1  scale
>>
>> 0  dup  4  0  360  arc   closepath   stroke
>>
>> showpage
>>
>>
>>
>> But at east and west the line thickness is bigger as at north and
>>
>> south. Is it possible to draw an ellipse which has a constant line
>>
>> thickness?
>>
>>
>>
>> --
>>
>> Cecil Westerhof
>>
>> Senior Software Engineer
>>
>> LinkedIn: http://www.linkedin.com/in/cecilwesterhof
>
> Reverse the scale before calling stroke:
>
> 0  dup  4  0  360  arc   closepath   .25 1 scale stroke

Works like a charm. I used it for:
       4   4  translate
      20  20  translate
      gsave
          4 {
               4  1  scale
               0  dup  5  0  360  arc   closepath
              .25 1  scale
              stroke
              45  rotate
          } repeat
      grestore
      0  dup  5  0  360  arc  closepath   fill

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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#2015

In article <87lhpzzshu.fsf@Equus.decebal.nl>, Cecil@decebal.nl says...

> > Reverse the scale before calling stroke:
> >
> > 0  dup  4  0  360  arc   closepath   .25 1 scale stroke

Or just use gsave/grestore:

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#2009

Cecil Westerhof <Cecil@decebal.nl> writes:

> With the following code I can draw an ellipse:
>     25  dup  translate
>      2  setlinewidth
>      4  1  scale
>      0  dup  4  0  360  arc   closepath   stroke
>     showpage
>
> But at east and west the line thickness is bigger as at north and
> south. Is it possible to draw an ellipse which has a constant line
> thickness?

You can get it pretty close to an ellipse, with even line thickness, not
by using scale, but by using curveto. Unfortunately, my usual function
for doing this isn't handy on this computer, but
http://www.tinaja.com/glib/ellipse4.pdf looks well-conceived. Searching
for Bézier postscript ellipse might find you some further good stuff.

-- Mark

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#2011

On Wed, 03 Sep 2014 19:50:19 +0200, Cecil Westerhof wrote:

> With the following code I can draw an ellipse:
>     25  dup  translate
>      2  setlinewidth
>      4  1  scale
>      0  dup  4  0  360  arc   closepath   stroke
>     showpage
> 
> But at east and west the line thickness is bigger as at north and
> south. Is it possible to draw an ellipse which has a constant line
> thickness?

I'd try reordering the 2nd and 3rd lines, so:

>     25  dup  translate
>      4  1  scale
>      2  setlinewidth
>      0  dup  4  0  360  arc   closepath   stroke

Does that help for you? Cheers, -- tlvp
-- 
Avant de repondre, jeter la poubelle, SVP.

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