Bug in latest beta, shifted metapost (possibly with drawarrow)

Bug in latest beta, shifted metapost (possibly with drawarrow)

[Mikael P. Sundqvist]

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Dear list,

the example below has shifted axes. I updated to the latest standalone
earlier today. The problem was not present some weeks ago.

In particular look at the red line that should start from the origin...

\starttext
\startMPpage
ut:=1.0cm;
ux:=0.6cm;

vardef diffp(expr riktn) =
 ((-1,0)--(1,0)) rotatedaround (origin,angle(ut,riktn*ux))
enddef;

path taxel,xaxel;
taxel:=((-1.4,0)--(5.4,0));
xaxel:=((0,-1.4)--(0,4.6));
drawarrow taxel xyscaled(ut,ux);
drawarrow xaxel xyscaled(ut,ux);

label.bot("$t$", (point length(taxel) of taxel) xyscaled(ut,ux));
label.lft("$P$", (point length(xaxel) of xaxel) xyscaled(ut,ux));

draw image(
 vardef fun(expr t, x) = x*(3-x) enddef;
 for i=-1 step 0.5 until 5 :
  for j=-1 step 0.5 until 4 :
    ii:=i;
    jj:=j;
    draw diffp(fun(ii,jj)) scaled 2bp shifted (ii*ut,jj*ux);
  endfor;
 endfor;

draw function (2, "x", "3/(1+2*exp(-3*x))" ,-1, 5, 1/5) xyscaled (ut,ux);

draw (0,0)--(3,3) xyscaled(ut,ux) withcolor darkred;

);
\stopMPpage
\stoptext

/Mikael

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Re: Bug in latest beta, shifted metapost (possibly with drawarrow)

[Hans Hagen]

On 11/3/2016 5:09 PM, Mikael P. Sundqvist wrote:
> Dear list,
>
> the example below has shifted axes. I updated to the latest standalone
> earlier today. The problem was not present some weeks ago.
>
> In particular look at the red line that should start from the origin...
>
> \starttext
> \startMPpage
> ut:=1.0cm;
> ux:=0.6cm;
>
> vardef diffp(expr riktn) =
>  ((-1,0)--(1,0)) rotatedaround (origin,angle(ut,riktn*ux))
> enddef;
>
> path taxel,xaxel;
> taxel:=((-1.4,0)--(5.4,0));
> xaxel:=((0,-1.4)--(0,4.6));
> drawarrow taxel xyscaled(ut,ux);
> drawarrow xaxel xyscaled(ut,ux);
>
> label.bot("$t$", (point length(taxel) of taxel) xyscaled(ut,ux));
> label.lft("$P$", (point length(xaxel) of xaxel) xyscaled(ut,ux));
>
> draw image(
>  vardef fun(expr t, x) = x*(3-x) enddef;
>  for i=-1 step 0.5 until 5 :
>   for j=-1 step 0.5 until 4 :
>     ii:=i;
>     jj:=j;
>     draw diffp(fun(ii,jj)) scaled 2bp shifted (ii*ut,jj*ux);
>   endfor;
>  endfor;
>
> draw function (2, "x", "3/(1+2*exp(-3*x))" ,-1, 5, 1/5) xyscaled (ut,ux);
>
> draw (0,0)--(3,3) xyscaled(ut,ux) withcolor darkred;
>
> );
> \stopMPpage
> \stoptext

I'll fix it. Alan: we really need this one then:

vardef image@#(text t) =
     save currentpicture ;
     picture currentpicture ;
     currentpicture := nullpicture ;
     t ;
     currentpicture
     if str @# <> "" :
         shifted (
               mfun_labxf@#               * lrcorner currentpicture
          +                 mfun_labyf@#  * ulcorner currentpicture
          + (1-mfun_labxf@#-mfun_labyf@#) * llcorner currentpicture
         )
     fi
enddef ;




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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/
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___________________________________________________________________________________