MetaPost cutdraw

MetaPost cutdraw

[Henning Hraban Ramm via ntg-context]

Hi, I’m trying to understand MetaPost better.

I’d like to draw a fat line that’s cut at its end points.
I learned, “cutdraw” should do the trick, but I get a parallelogram 
instead of a rectangle.

What’s wrong?

Hraban


\startMPpage

draw (0,20)--(20,20) withpen pensquare scaled 10;

cutdraw (0,0)--(20,0) withpen pensquare scaled 10;

% just to show start and end
draw (0,-10)--(0,30);
draw (20,-10)--(20,30);

\stopMPpage
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Re: MetaPost cutdraw

[Aditya Mahajan via ntg-context]

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On Wed, 6 Jul 2022, Henning Hraban Ramm via ntg-context wrote:

> Hi, I’m trying to understand MetaPost better.
> 
> I’d like to draw a fat line that’s cut at its end points.

You mean like linecap = butt?

\startMPpage[offset=5mm]
  path p;

  p := origin -- (7cm,0);
  interim  linecap := butt;
  draw p withpen pencircle scaled 5mm;

  p := p shifted (0,2cm);
  interim  linecap := rounded;
  draw p withpen pencircle scaled 5mm;

  p := p shifted (0,2cm);
  interim  linecap := squared;
  draw p withpen pencircle scaled 5mm;

\stopMPpage

> I learned, “cutdraw” should do the trick, but I get a parallelogram 
> instead of a rectangle.

Seems to be something weird with pensquare:

\startMPpage[offset=5mm]
  path p;

  p := origin -- (7cm,0);
  % interim  linecap := butt;
  cutdraw p withpen pensquare scaled 5mm;

  p := p shifted (0,2cm);
  interim  linecap := rounded;
  draw p withpen pensquare scaled 5mm;

  p := p shifted (0,2cm);
  interim  linecap := squared;
  draw p withpen pensquare scaled 5mm;

\stopMPpage

Aditya

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Re: MetaPost cutdraw

[Hans Hagen via ntg-context]

On 7/6/2022 7:10 AM, Aditya Mahajan via ntg-context wrote:
> On Wed, 6 Jul 2022, Henning Hraban Ramm via ntg-context wrote:
> 
>> Hi, I’m trying to understand MetaPost better.
>>
>> I’d like to draw a fat line that’s cut at its end points.
> 
> You mean like linecap = butt?
> 
> \startMPpage[offset=5mm]
>    path p;
> 
>    p := origin -- (7cm,0);
>    interim  linecap := butt;
>    draw p withpen pencircle scaled 5mm;
> 
>    p := p shifted (0,2cm);
>    interim  linecap := rounded;
>    draw p withpen pencircle scaled 5mm;
> 
>    p := p shifted (0,2cm);
>    interim  linecap := squared;
>    draw p withpen pencircle scaled 5mm;
> 
> \stopMPpage
> 
>> I learned, “cutdraw” should do the trick, but I get a parallelogram
>> instead of a rectangle.
> 
> Seems to be something weird with pensquare:
> 
> \startMPpage[offset=5mm]
>    path p;
> 
>    p := origin -- (7cm,0);
>    % interim  linecap := butt;
>    cutdraw p withpen pensquare scaled 5mm;
> 
>    p := p shifted (0,2cm);
>    interim  linecap := rounded;
>    draw p withpen pensquare scaled 5mm;
> 
>    p := p shifted (0,2cm);
>    interim  linecap := squared;
>    draw p withpen pensquare scaled 5mm;
> 
> \stopMPpage
\startMPpage[offset=5mm]
     path p;

     p := origin -- (7cm,0);

     interim  linecap := squared;

     draw p withpen ((pensquare            ) scaled 5mm) withcolor red ;
     draw envelope  ((pensquare            ) scaled 5mm) of p withcolor 
green ;
     draw envelope  ((pensquare rotated eps) scaled 5mm) of p withcolor 
blue ;
\stopMPpage

(there is an "ontarget" chapter about envelopes; mikael and i spent 
quite some time figuring out a few things but in the end conclused that 
mp des the right thing given the strategy it folows but it definitely 
has side effects)

Hans


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: MetaPost cutdraw

[Henning Hraban Ramm via ntg-context]

Am 06.07.22 um 09:15 schrieb Hans Hagen via ntg-context:
> On 7/6/2022 7:10 AM, Aditya Mahajan via ntg-context wrote:
>> On Wed, 6 Jul 2022, Henning Hraban Ramm via ntg-context wrote:
>>
>>> Hi, I’m trying to understand MetaPost better.
>>>
>>> I’d like to draw a fat line that’s cut at its end points.
>>
>> You mean like linecap = butt?

Yes, but that doesn’t behave differently.


> \startMPpage[offset=5mm]
>      path p;
> 
>      p := origin -- (7cm,0);
> 
>      interim  linecap := squared;
> 
>      draw p withpen ((pensquare            ) scaled 5mm) withcolor red ;
>      draw envelope  ((pensquare            ) scaled 5mm) of p withcolor 
> green ;
>      draw envelope  ((pensquare rotated eps) scaled 5mm) of p withcolor 
> blue ;
> \stopMPpage
> 
> (there is an "ontarget" chapter about envelopes; mikael and i spent 
> quite some time figuring out a few things but in the end conclused that 
> mp des the right thing given the strategy it folows but it definitely 
> has side effects)

Thank you for the insight, but does that mean I can’t get my “butt 
capped” lines and I must shorten the lines by half the pen size?

Hraban

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___________________________________________________________________________________

Re: MetaPost cutdraw

[Mikael Sundqvist via ntg-context]

Hi,

On Wed, Jul 6, 2022 at 11:29 AM Henning Hraban Ramm via ntg-context
<ntg-context@ntg.nl> wrote:
>
> Am 06.07.22 um 09:15 schrieb Hans Hagen via ntg-context:
> > On 7/6/2022 7:10 AM, Aditya Mahajan via ntg-context wrote:
> >> On Wed, 6 Jul 2022, Henning Hraban Ramm via ntg-context wrote:
> >>
> >>> Hi, I’m trying to understand MetaPost better.
> >>>
> >>> I’d like to draw a fat line that’s cut at its end points.
> >>
> >> You mean like linecap = butt?
>
> Yes, but that doesn’t behave differently.
>
>
> > \startMPpage[offset=5mm]
> >      path p;
> >
> >      p := origin -- (7cm,0);
> >
> >      interim  linecap := squared;
> >
> >      draw p withpen ((pensquare            ) scaled 5mm) withcolor red ;
> >      draw envelope  ((pensquare            ) scaled 5mm) of p withcolor
> > green ;
> >      draw envelope  ((pensquare rotated eps) scaled 5mm) of p withcolor
> > blue ;
> > \stopMPpage
> >
> > (there is an "ontarget" chapter about envelopes; mikael and i spent
> > quite some time figuring out a few things but in the end conclused that
> > mp des the right thing given the strategy it folows but it definitely
> > has side effects)
>
> Thank you for the insight, but does that mean I can’t get my “butt
> capped” lines and I must shorten the lines by half the pen size?
>
> Hraban
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
>
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
> archive  : https://bitbucket.org/phg/context-mirror/commits/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________

Hraban,

with the new upload you can do

\startMPpage[offset=1dk]
pickup pencircle scaled 4 ;
path p ; p := origin -- (20,0) ;
draw p withcolor darkyellow ;
draw p yshifted 5 withlinecap butt withcolor darkred ;
draw p yshifted -5 withlinecap squared withcolor darkgreen ;
for i within currentpicture :
drawpoints pathpart i withpen pencircle scaled 1 ;
endfor ;
\stopMPpage

That is, you can set linecap for each draw. I hope it helps.

/Mikael
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