Bug in lmt_arrow

Bug in lmt_arrow

[Aditya Mahajan via ntg-context]

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Hi,

There is a bug in lmt_arrow. If given a "non-cycle" path, lmt_arrow completes the cycle. 

    \starttext

    \startMPcode
      newpath p;
      ahfactor := 5;
      p := origin .. (1cm, 1cm) .. (2cm, 0);
      draw lmt_arrow
           [
             path = p, 
             location = "percentage",
             percentage = 50,
             alternative = "curved", 
           ]
           withpen pencircle scaled 1bp;
    \stopMPcode
    \stoptext

With 2021.11.11, I get the attached file. Note that lmt_arrow has drawn the "cycle" version of the path, even though p does not have a cycle.

I have looked at the code and cannot figure out why this is happening.

Thanks,
Aditya

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Re: Bug in lmt_arrow

[Hans Hagen via ntg-context]

On 11/14/2021 4:33 AM, Aditya Mahajan via ntg-context wrote:
> Hi,
> 
> There is a bug in lmt_arrow. If given a "non-cycle" path, lmt_arrow completes the cycle.
> 
>      \starttext
> 
>      \startMPcode
>        newpath p;
>        ahfactor := 5;
>        p := origin .. (1cm, 1cm) .. (2cm, 0);
>        draw lmt_arrow
>             [
>               path = p,
>               location = "percentage",
>               percentage = 50,
>               alternative = "curved",
>             ]
>             withpen pencircle scaled 1bp;
>      \stopMPcode
>      \stoptext
> 
> With 2021.11.11, I get the attached file. Note that lmt_arrow has drawn the "cycle" version of the path, even though p does not have a cycle.
> 
> I have looked at the code and cannot figure out why this is happening.

it happens in the 'direct' variant (metapost.registerdirect) where a 
boolean is passed as signal and that boolean then is also picked up by 
the (shared) path injector as (old school) signal that a path is closed 
while it should instead consutl the closed field in a path table (sounds 
more complex than it is)

so in the end it is a nasty side effect of the fast inject code path 
(shared function with different stack values; i'll probably have to 
ditch a "low level backward compatibility feature no one uses anyway" 
some day)

i uploaded a fix that you can test when the bins are compiled at

	https://build.contextgarden.net/#/waterfall?tags=c.luametatex

new bins then in:

	https://dl.contextgarden.net/build/luametatex/

(fyi: in the mp code you see that the path p is 'get' from the lua end 
where it got passed to by parameter)

(interesting that it didn't show up sooner, maybe most users have closed 
paths and/or most lmt_ features used closed paths)

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: Bug in lmt_arrow

[Aditya Mahajan via ntg-context]

On Sun, 14 Nov 2021, Hans Hagen wrote:

> On 11/14/2021 4:33 AM, Aditya Mahajan via ntg-context wrote:
> > Hi,
> > 
> > There is a bug in lmt_arrow. If given a "non-cycle" path, lmt_arrow
> > completes the cycle.
> > 
> >      \starttext
> > 
> >      \startMPcode
> >        newpath p;
> >        ahfactor := 5;
> >        p := origin .. (1cm, 1cm) .. (2cm, 0);
> >        draw lmt_arrow
> >             [
> >               path = p,
> >               location = "percentage",
> >               percentage = 50,
> >               alternative = "curved",
> >             ]
> >             withpen pencircle scaled 1bp;
> >      \stopMPcode
> >      \stoptext
> > 
> > With 2021.11.11, I get the attached file. Note that lmt_arrow has drawn the
> > "cycle" version of the path, even though p does not have a cycle.
> > 
> > I have looked at the code and cannot figure out why this is happening.
> 
> it happens in the 'direct' variant (metapost.registerdirect) where a boolean
> is passed as signal and that boolean then is also picked up by the (shared)
> path injector as (old school) signal that a path is closed while it should
> instead consutl the closed field in a path table (sounds more complex than it
> is)
> 
> so in the end it is a nasty side effect of the fast inject code path (shared
> function with different stack values; i'll probably have to ditch a "low level
> backward compatibility feature no one uses anyway" some day)
> 
> i uploaded a fix that you can test when the bins are compiled at
> 
> 	https://build.contextgarden.net/#/waterfall?tags=c.luametatex
> 
> new bins then in:
> 
> 	https://dl.contextgarden.net/build/luametatex/
> 
> (fyi: in the mp code you see that the path p is 'get' from the lua end where
> it got passed to by parameter)

Thanks! Works perfectly here.

> (interesting that it didn't show up sooner, maybe most users have closed paths
> and/or most lmt_ features used closed paths)

I was reusing two year old code and took me a while to figure out why the output was suddenly wrong. 

Aditya
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Re: Bug in lmt_arrow

[Aditya Mahajan via ntg-context]

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On Sun, 14 Nov 2021, Aditya Mahajan via ntg-context wrote:

> On Sun, 14 Nov 2021, Hans Hagen wrote:
> 
> > On 11/14/2021 4:33 AM, Aditya Mahajan via ntg-context wrote:
> > > Hi,
> > > 
> > > There is a bug in lmt_arrow. If given a "non-cycle" path, lmt_arrow
> > > completes the cycle.
> > > 
> > >      \starttext
> > > 
> > >      \startMPcode
> > >        newpath p;
> > >        ahfactor := 5;
> > >        p := origin .. (1cm, 1cm) .. (2cm, 0);
> > >        draw lmt_arrow
> > >             [
> > >               path = p,
> > >               location = "percentage",
> > >               percentage = 50,
> > >               alternative = "curved",
> > >             ]
> > >             withpen pencircle scaled 1bp;
> > >      \stopMPcode
> > >      \stoptext
> > > 
> > > With 2021.11.11, I get the attached file. Note that lmt_arrow has drawn the
> > > "cycle" version of the path, even though p does not have a cycle.
> > > 
> > > I have looked at the code and cannot figure out why this is happening.
> > 
> > it happens in the 'direct' variant (metapost.registerdirect) where a boolean
> > is passed as signal and that boolean then is also picked up by the (shared)
> > path injector as (old school) signal that a path is closed while it should
> > instead consutl the closed field in a path table (sounds more complex than it
> > is)
> > 
> > so in the end it is a nasty side effect of the fast inject code path (shared
> > function with different stack values; i'll probably have to ditch a "low level
> > backward compatibility feature no one uses anyway" some day)
> > 
> > i uploaded a fix that you can test when the bins are compiled at
> > 
> > 	https://build.contextgarden.net/#/waterfall?tags=c.luametatex
> > 
> > new bins then in:
> > 
> > 	https://dl.contextgarden.net/build/luametatex/
> > 
> > (fyi: in the mp code you see that the path p is 'get' from the lua end where
> > it got passed to by parameter)
> 
> Thanks! Works perfectly here.

Spoke too soon. Now straight lines don't work:

    \starttext

    \startMPcode
      newpath p;
      ahfactor := 5;
      p := origin .. (3cm,0);
      draw lmt_arrow
           [
             path = p, 
             location = "percentage",
             percentage = 50,
             alternative = "curved", 
           ]
           withpen pencircle scaled 1bp;
    \stopMPcode
    \stoptext


gives

metapost        > trace > This is MPLIB for LuaMetaTeX, version 3.11, running in scaled mode.
metapost        > trace > 
metapost        > trace > loading metafun for lmtx, including the plain 1.004 base definitions
metapost        > trace > 
metafun         > log >
metafun         > log > error: This can't happen (division by zero)
metafun         > log >
metapost        > trace > <macro> arrowhead -> <expr> -> begingroup.save.q,e,r;pair.e;e=point.length(EXPR2)of(EXPR2);path.q;q=gobble((EXPR2)shifted-e.cutafter.makepath(pencircle.scaled(2ahlength)))cuttings;if.ahvariant>0:path.r;r=gobble((EXPR2)shifted-e.cutafter.makepath(pencircle.scaled((1-ahdimple)*2ahlength)))cuttings;fi(q.rotated(ahangle/2)&reverse.q.rotated-(ahangle/2)if.ahvariant=1:--point0of.r--elseif.ahvariant=2:...point0of.r...else:--fi.cycle)shifted.e.endgroup
metapost        > trace > <to be read again> endgroup
metapost        > trace > <argument> pushparameters "arrow" ; save a ; string a ; a := getparameter "alternative" ; save l ; string l ; l := getparameter "location" ; save k ; string k ; k := getparameter "kind" ; save p ; path p ; p := getparameter "path" ; interim ahvariant := if a = "dimpled" : 1 elseif a = "curved" : 2 else : 0 fi ; interim ahdimple := getparameter "dimple" ; interim ahscale := getparameter "scale" ; interim ahangle := getparameter "angle" ; interim ahlength := getparameter "length" ; if not getparameter "headonly" : draw p ; fi ; if hasparameter "pen" : if hasoption "pen" "auto" : ahlength := ( getparameter "penscale" ) * boundingradius ( currentpen ) ; else : ahlength := ( getparameter "penscale" ) * boundingradius ( getparameterpen "pen" ) ; fi ; fi ; if k = "draw" : draw elseif k = "both" : filldraw else : fill fi if l = "middle" : midarrowhead p ; elseif l = "percentage" : arrowheadonpath ( p , ( getparameter "percentage" ) / 100 ) ; elseif l = "both" : arrowhead p ; if k = "draw" : draw elseif k = "both" : filldraw else : fill fi arrowhead reverse p ; else : arrowhead p ; fi ; popparameters ;
metapost        > trace > <macro> image -> (TEXT3)-> begingroup.save.currentpicture;picture.currentpicture;currentpicture:=nullpicture;(TEXT3);currentpicture.if.str(SUFFIX2)<>"":shifted(mfun_labxf(SUFFIX2)*lrcorner.p+mfun_labyf(SUFFIX2)*ulcorner.p+(1-mfun_labxf(SUFFIX2)-mfun_labyf(SUFFIX2))*llcorner.p)fi.endgroup
metapost        > trace > <macro> lmt_do_arrow -> -> begingroup.image(pushparameters"arrow";save.a;string.a;a:=getparameter"alternative";save.l;string.l;l:=getparameter"location";save.k;string.k;k:=getparameter"kind";save.p;path.p;p:=getparameter"path";interim.ahvariant:=if.a="dimpled":1elseif.a="curved":2else:0fi;interim.ahdimple:=getparameter"dimple";interim.ahscale:=getparameter"scale";interim.ahangle:=getparameter"angle";interim.ahlength:=getparameter"length";if.not.getparameter"headonly":draw.p;fi;if.hasparameter"pen":if.hasoption"pen""auto":ahlength:=(getparameter"penscale")*boundingradius(currentpen);else:ahlength:=(getparameter"penscale")*boundingradius(getparameterpen"pen");fi;fi;if.k="draw":draw.elseif.k="both":filldraw.else:fill.fi.if.l="middle":midarrowhead.p;elseif.l="percentage":arrowheadonpath(p,(getparameter"percentage")/100);elseif.l="both":arrowhead.p;if.k="draw":draw.elseif.k="both":filldraw.else:fill.fi.arrowhead.reverse.p;else:arrowhead.p;fi;popparameters;)endgroup
metapost        > trace > <scantokens> lmt_do_arrow
metafun         > log >
metafun         > log > I'm broken. Please show this to someone who can fix can fix it and try
again
metafun         > log >
metapost        > trace > <direct> newpath p; ahfactor := 5; p := origin .. (3cm,0); draw lmt_arrow [ path = p, location = "percentage", percentage = 50, alternative = "curved", ] withpen pencircle scaled 1bp; ;
metapost        > trace > 


Aditya

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Re: Bug in lmt_arrow

[Hans Hagen via ntg-context]

On 11/15/2021 4:07 AM, Aditya Mahajan wrote:
> On Sun, 14 Nov 2021, Aditya Mahajan via ntg-context wrote:
> 
>> On Sun, 14 Nov 2021, Hans Hagen wrote:
>>
>>> On 11/14/2021 4:33 AM, Aditya Mahajan via ntg-context wrote:
>>>> Hi,
>>>>
>>>> There is a bug in lmt_arrow. If given a "non-cycle" path, lmt_arrow
>>>> completes the cycle.
>>>>
>>>>       \starttext
>>>>
>>>>       \startMPcode
>>>>         newpath p;
>>>>         ahfactor := 5;
>>>>         p := origin .. (1cm, 1cm) .. (2cm, 0);
>>>>         draw lmt_arrow
>>>>              [
>>>>                path = p,
>>>>                location = "percentage",
>>>>                percentage = 50,
>>>>                alternative = "curved",
>>>>              ]
>>>>              withpen pencircle scaled 1bp;
>>>>       \stopMPcode
>>>>       \stoptext
>>>>
>>>> With 2021.11.11, I get the attached file. Note that lmt_arrow has drawn the
>>>> "cycle" version of the path, even though p does not have a cycle.
>>>>
>>>> I have looked at the code and cannot figure out why this is happening.
>>>
>>> it happens in the 'direct' variant (metapost.registerdirect) where a boolean
>>> is passed as signal and that boolean then is also picked up by the (shared)
>>> path injector as (old school) signal that a path is closed while it should
>>> instead consutl the closed field in a path table (sounds more complex than it
>>> is)
>>>
>>> so in the end it is a nasty side effect of the fast inject code path (shared
>>> function with different stack values; i'll probably have to ditch a "low level
>>> backward compatibility feature no one uses anyway" some day)
>>>
>>> i uploaded a fix that you can test when the bins are compiled at
>>>
>>> 	https://build.contextgarden.net/#/waterfall?tags=c.luametatex
>>>
>>> new bins then in:
>>>
>>> 	https://dl.contextgarden.net/build/luametatex/
>>>
>>> (fyi: in the mp code you see that the path p is 'get' from the lua end where
>>> it got passed to by parameter)
>>
>> Thanks! Works perfectly here.
> 
> Spoke too soon. Now straight lines don't work:

new attempt (submitted to build)


-----------------------------------------------------------------
                                           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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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
___________________________________________________________________________________

Re: Bug in lmt_arrow

[Aditya Mahajan via ntg-context]

On Mon, 15 Nov 2021, Hans Hagen wrote:

> On 11/15/2021 4:07 AM, Aditya Mahajan wrote:
> > On Sun, 14 Nov 2021, Aditya Mahajan via ntg-context wrote:
> > 
> > > On Sun, 14 Nov 2021, Hans Hagen wrote:
> > > 
> > 
> > Spoke too soon. Now straight lines don't work:
> 
> new attempt (submitted to build)

The following still fails with ver 2021.11.19 

    \starttext

    \startMPcode
      newpath p;
      ahfactor := 5;
      p := origin .. (3cm,0);
      draw lmt_arrow
           [
             path = p, 
             location = "percentage",
             percentage = 50,
             alternative = "curved", 
           ]
           withpen pencircle scaled 1bp;
    \stopMPcode
    \stoptext

I get an error:

metafun         > log >
metafun         > log > error: This can't happen (division by zero)
metafun         > log >

Thanks,
Aditya
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Re: Bug in lmt_arrow

[Hans Hagen via ntg-context]

On 11/20/2021 6:53 AM, Aditya Mahajan via ntg-context wrote:
> On Mon, 15 Nov 2021, Hans Hagen wrote:
> 
>> On 11/15/2021 4:07 AM, Aditya Mahajan wrote:
>>> On Sun, 14 Nov 2021, Aditya Mahajan via ntg-context wrote:
>>>
>>>> On Sun, 14 Nov 2021, Hans Hagen wrote:
>>>>
>>>
>>> Spoke too soon. Now straight lines don't work:
>>
>> new attempt (submitted to build)
> 
> The following still fails with ver 2021.11.19
> 
>      \starttext
> 
>      \startMPcode
>        newpath p;
>        ahfactor := 5;
>        p := origin .. (3cm,0);
>        draw lmt_arrow
>             [
>               path = p,
>               location = "percentage",
>               percentage = 50,
>               alternative = "curved",
>             ]
>             withpen pencircle scaled 1bp;
>      \stopMPcode
>      \stoptext
> 
> I get an error:
> 
> metafun         > log >
> metafun         > log > error: This can't happen (division by zero)
> metafun         > log >
bah, cycling between two failing tests ... new bin will be made on the 
farm in a moment

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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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
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___________________________________________________________________________________

Re: Bug in lmt_arrow

[Aditya Mahajan via ntg-context]

On Sat, 20 Nov 2021, Hans Hagen wrote:
> On 11/20/2021 6:53 AM, Aditya Mahajan via ntg-context wrote:
> > On Mon, 15 Nov 2021, Hans Hagen wrote:
> > 
> > > On 11/15/2021 4:07 AM, Aditya Mahajan wrote:
> > > > On Sun, 14 Nov 2021, Aditya Mahajan via ntg-context wrote:
> > > > 
> > > > > On Sun, 14 Nov 2021, Hans Hagen wrote:
> > > > > 
> > > > 
> > > > Spoke too soon. Now straight lines don't work:
> > > 
> > > new attempt (submitted to build)
> > 
> > The following still fails with ver 2021.11.19
> > 
> >      \starttext
> > 
> >      \startMPcode
> >        newpath p;
> >        ahfactor := 5;
> >        p := origin .. (3cm,0);
> >        draw lmt_arrow
> >             [
> >               path = p,
> >               location = "percentage",
> >               percentage = 50,
> >               alternative = "curved",
> >             ]
> >             withpen pencircle scaled 1bp;
> >      \stopMPcode
> >      \stoptext
> > 
> > I get an error:
> > 
> > metafun         > log >
> > metafun         > log > error: This can't happen (division by zero)
> > metafun         > log >
> bah, cycling between two failing tests ... new bin will be made on the farm in
> a moment

Thanks! Works perfectly now.

Aditya
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