Re: clipping in metafun has weird side effects

[Hans Hagen <pragma@wxs.nl>]

On 10/31/2014 9:58 AM, Tobias Columbus wrote:
> Hi again,
>
> I tried my example from yesterday in context with metapost format, but
> the output still differs from what mptopdf produces.
>
> While doing that, I noticed that the mpost format is currently not usable out of
> the box:
>
> \startMPcode{metapost}
>    draw (0,0) -- (1cm,0) ;
> \stopMPcode
>
> produces the error message
>

\startMPcode
   draw (0,0) -- (1cm,0) ;
\stopMPcode

why the {metapost}

>>> mfun_first_run
>>> true
> ! Equation cannot be performed (numeric=boolean).
>
> and the same for 'mfun_trial_run'. Simply adding
>
> boolean mfun_trial_run, mfun_first_run ;
>
> to texmf/metapost/base/mpost.mp resolved the issue for me. However, that may
> introduce other complications that I have no idea of.
>
> Tobias
>
>
>
> On Thu, Oct 30, 2014 at 08:56:34PM +0100, Tobias Columbus wrote:
>> Dear all,
>>
>> I stumbled upon some very weird behaviour of clipping in metafun/context. When I
>> add some clipped pictures to currentpicture and draw something dashed, some
>> subsequent lines will also be drawn dashed.
>>
>> This behaviour only shows up with context but not with mptopdf or mpost. I
>> attached a minimal example and the corresponding output of context and mptopdf.
>>
>> I tried context versions 2014.05.21 22:04 and 2014.10.29 17:47, but the result
>> is the same in both.
>>
>> Tobias
>>
>>
>>
>>
>> --
>
>>
>> vardef mycircle =
>>    save c ; picture c ; c := nullpicture ;
>>    addto c contour fullcircle scaled 2mm ;
>>    c
>> enddef ;
>>
>> def a expr p =
>>    path _p_ ; _p_ := p ;
>>    a_impl
>> enddef ;
>>
>> def a_impl text t =
>>    begingroup
>>      save c ; picture c ; c := mycircle ;
>>      clip c to bbox c scaled 0.5 ;
>>      addto currentpicture also c t ;
>>      addto currentpicture doublepath _p_ t ;
>>    endgroup
>> enddef ;
>>
>> def b expr p =
>>    path _p_ ; _p_ := p ;
>>    b_impl
>> enddef ;
>>
>> def b_impl text t =
>>    begingroup
>>      save c; picture c ; c := mycircle ;
>>      addto currentpicture also c t ;
>>      addto currentpicture doublepath _p_ t ;
>>    endgroup
>> enddef ;
>> beginfig(1)
>>
>>    a (0,0) -- (1cm,0) dashed evenly ;
>>    currentpicture := currentpicture shifted (2cm,0) ;
>>    a (0,0) -- (1cm,0) ;
>>
>>    currentpicture := currentpicture shifted (-2cm, 0.5cm );
>>
>>    b (0,0) -- (1cm,0) dashed evenly ;
>>    currentpicture := currentpicture shifted (2cm,0) ;
>>    b (0,0) -- (1cm,0) ;
>>
>> endfig ;
>> end
>
>
>
>


-- 

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                                           Hans Hagen | PRAGMA ADE
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