Re: clipping in metafun has weird side effects

[Hans Hagen <pragma@wxs.nl>]

On 10/31/2014 10:15 AM, Tobias Columbus wrote:
> On Fri, Oct 31, 2014 at 10:05:35AM +0100, Hans Hagen wrote:
>> 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}
>
> I wanted to know if the impact of clipping is caused by the metafun format.
> According to the wiki page
> http://wiki.contextgarden.net/Command/defineMPinstance the instances "metapost"
> and "metafun" are predefined and can be used by
>
> \startMPcode{instance}
>    ...
> \stopMPcode
>
> where metafun is the default instance, i.e. used when there is no instance
> given.

i fixed the metapost run and also added basic text support in it (next 
beta)


>>
>>>>> 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
>>>
>>>
>>>
>>>
>>
>>
>> --
>>
>> -----------------------------------------------------------------
>>                                            Hans Hagen | PRAGMA ADE
>>                Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>>      tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
>>                                               | www.pragma-pod.nl
>> -----------------------------------------------------------------
>> ___________________________________________________________________________________
>> 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
>> ___________________________________________________________________________________
>


-- 

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
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
___________________________________________________________________________________