[NTG-context] MetaPost cutdraw

[Hans Hagen]

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


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                                           Hans Hagen | PRAGMA ADE
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