Square pens and dash pattern

Square pens and dash pattern

[Aditya Mahajan]

Hi,

There appears to be a metapost bug with square pens and dash patterns:

\starttext

\startMPcode
     pickup pencircle scaled 1bp;
     drawarrow origin -- (5cm, 4cm) dashed evenly;
     pickup pensquare scaled 1bp;
     drawarrow origin -- (5cm,-4cm) dashed evenly;
\stopMPcode

\stoptext

Note that the second arrow is not dashed at all! This is not due to the 
thick pen.

Aditya
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Re: Square pens and dash pattern

[Alan BRASLAU]

On Tue, 5 Apr 2016 19:44:33 -0400
Aditya Mahajan <adityam@umich.edu> wrote:

> There appears to be a metapost bug with square pens and dash patterns:

I confirm that dashed anything with a pensquare does not dash.

Alan
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Re: Square pens and dash pattern

[Hans Hagen]

On 4/6/2016 1:44 AM, Aditya Mahajan wrote:
> Hi,
>
> There appears to be a metapost bug with square pens and dash patterns:
>
> \starttext
>
> \startMPcode
>      pickup pencircle scaled 1bp;
>      drawarrow origin -- (5cm, 4cm) dashed evenly;
>      pickup pensquare scaled 1bp;
>      drawarrow origin -- (5cm,-4cm) dashed evenly;
> \stopMPcode
>
> \stoptext
>
> Note that the second arrow is not dashed at all! This is not due to the
> thick pen.

pencircles make simple round pens that are mapped directly onto ps 
primitives and there dashing applies (dashing is just passing data to 
the backend) ... afaik other penshapes can result in a filled path so no 
dashing applies

(but mp master luigi will tripple check it in the source for you so he 
might come up with another answer)

(and after that, as mathematical challenge, alan will write a mp macro 
that fakes the dashing)

Hans

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Re: Square pens and dash pattern

[luigi scarso]

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On Wed, Apr 6, 2016 at 9:52 AM, Hans Hagen <pragma@wxs.nl> wrote:

> On 4/6/2016 1:44 AM, Aditya Mahajan wrote:
>
>> Hi,
>>
>> There appears to be a metapost bug with square pens and dash patterns:
>>
>> \starttext
>>
>> \startMPcode
>>      pickup pencircle scaled 1bp;
>>      drawarrow origin -- (5cm, 4cm) dashed evenly;
>>      pickup pensquare scaled 1bp;
>>      drawarrow origin -- (5cm,-4cm) dashed evenly;
>> \stopMPcode
>>
>> \stoptext
>>
>> Note that the second arrow is not dashed at all! This is not due to the
>> thick pen.
>>
>
> pencircles make simple round pens that are mapped directly onto ps
> primitives and there dashing applies (dashing is just passing data to the
> backend) ... afaik other penshapes can result in a filled path so no
> dashing applies
>
> (but mp master luigi will tripple check it in the source for you so he
> might come up with another answer)
>
> (and after that, as mathematical challenge, alan will write a mp macro
> that fakes the dashing)
>
> Hans
>
>


 # cat test-square.mp test-circle.mp
beginfig(1);
tracingall;
%pickup pencircle scaled 1bp;
%drawarrow origin -- (5cm, 4cm) dashed evenly;
pickup pensquare scaled 1bp;
drawarrow origin -- (5cm,-4cm) dashed evenly;
endfig;
end.



beginfig(1);
tracingall;
pickup pencircle scaled 1bp;
drawarrow origin -- (5cm, 4cm) dashed evenly;
%pickup pensquare scaled 1bp;
%drawarrow origin -- (5cm,-4cm) dashed evenly;
endfig;
end.

 # mpost test-square.mp
says, near the end,


Edge structure at line 7 (just shipped out):
Filled pen stroke :
(0,0)..controls (47.24408,-37.79527) and (94.48817,-75.59053)
 ..(141.73225,-113.3858)
dashed (on 3 off 3) shifted 0 (this will be ignored)


while
# mpost test-circle.mp
says

Edge structure at line 7 (just shipped out):
Filled pen stroke :
(0,0)..controls (47.24408,37.79527) and (94.48817,75.59053)
 ..(141.73225,113.3858)
dashed (on 3 off 3) shifted 0

So it doesn't look  a mpost bug .

-- 
luigi

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___________________________________________________________________________________
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://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________