Re: Code that run in Metapost but not in starMPcode enviroment

Re: Code that run in Metapost but not in starMPcode enviroment

[Akira Kakuto]

> Interestingly it seems to work in mkii, probably because
> mkii calls external metafun:

Sorry,  I didn't notice explanation by Hans.

Best,
Akira

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Re: Code that run in Metapost but not in starMPcode enviroment

[Hans Hagen]

On 2/1/2015 3:31 PM, Akira Kakuto wrote:
>> Interestingly it seems to work in mkii, probably because
>> mkii calls external metafun:
>
> Sorry,  I didn't notice explanation by Hans.

The problem with variables in metapost is that they are global by 
default (unless 'save'd in a group or vardef). This means that one can 
best explicitly declare variables that are used. Of course one can also 
use a dedicated instance.

Hans

-----------------------------------------------------------------
                                           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
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Code that run in Metapost but not in starMPcode enviroment

[Akira Kakuto]

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> What is wrong with this code?

Interestingly it seems to work in mkii, probably because
mkii calls external metafun:

context --pdftex --passon=--shell-escape test.tex

test.pdf is attached.

Best,
Akira

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Re: Code that run in Metapost but not in starMPcode enviroment

[Hans Hagen]

On 2/1/2015 12:29 PM, DesdeChaves wrote:
>
> I'm trying to draw some random arrows using Metapost. For that I use a
> piece of code from fpast that in found at stackexchange
> <http://tex.stackexchange.com/questions/179745/generating-random-arrows-in-tikz/180111#180111>
>
> Unfortunately this code does not work in context (request for a solution
> <http://tex.stackexchange.com/questions/225864/metapost-error-related-with-context>)
> because the freelabel() function. If I disable it the result is the
> expected.
> What is wrong with this code?
>
>
> \starttext
>
> \startMPcode
> numeric u, nb_vectors, wd;
> u := 1cm; % unit length
> nb_vectors := 20; wd = .5;
> boolean intersect; pair random_origin; color random_color; path
> candidate, random_vector[];
> %
> vardef bb(expr p) =
>    save orig, extr; pair orig, extr; orig = point 0 of p; extr = point 1
> of p;
>    pair v,w; v = wd*unitvector(extr-orig)*u; w = v rotated 90;
>    (orig - v + w) -- (extr + v + w) -- (extr + v - w) -- (orig - v - w)
> -- cycle
> enddef;
> %
>
>    pickup pencircle scaled 2bp;

   numeric i ;
   i = 1 ;

>    i = 1;

or

  i := 1 ; % never assume variable is not set global (such is mp)

>    forever:
>      exitunless (i <=  nb_vectors);
>      intersect := false;
>      random_length := u*(2+uniformdeviate(1));
>      random_angle := uniformdeviate(359);
>      random_origin := u*(uniformdeviate(wd*nb_vectors),
> uniformdeviate(wd*nb_vectors));
>      random_color := (uniformdeviate(1), uniformdeviate(1),
> uniformdeviate(1));
>      candidate := random_origin -- (random_origin +
> random_length*dir(random_angle));
>      j := 1;
>      forever:
>        exitif (j = i) or (intersect = true);
>        if bb(random_vector[j]) intersectiontimes bb(candidate) <>  (-1, -1):
>          intersect := true;
>        fi;
>        j := j+1;
>      endfor;
>      if intersect = false:
>        random_vector[i] = candidate;
>        drawarrow candidate withcolor random_color;
>        freelabel(btex $v$ etex, point .5 of candidate, point .5 of
> candidate + dir (random_angle + 90));
>        i := i+1;
>      fi;
>    endfor;
> \stopMPcode
>
>
> \stoptext
>
>
> ___________________________________________________________________________________
> 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
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___________________________________________________________________________________

Code that run in Metapost but not in starMPcode enviroment

[DesdeChaves]

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I'm trying to draw some random arrows using Metapost. For that I use a
piece of code from fpast that in found at stackexchange
<http://tex.stackexchange.com/questions/179745/generating-random-arrows-in-tikz/180111#180111>

Unfortunately this code does not work in context (request for a solution
<http://tex.stackexchange.com/questions/225864/metapost-error-related-with-context>)
because the freelabel() function. If I disable it the result is the
expected.
What is wrong with this code?


\starttext

\startMPcode
numeric u, nb_vectors, wd;
u := 1cm; % unit length
nb_vectors := 20; wd = .5;
boolean intersect; pair random_origin; color random_color; path candidate,
random_vector[];
%
vardef bb(expr p) =
  save orig, extr; pair orig, extr; orig = point 0 of p; extr = point 1 of
p;
  pair v,w; v = wd*unitvector(extr-orig)*u; w = v rotated 90;
  (orig - v + w) -- (extr + v + w) -- (extr + v - w) -- (orig - v - w) --
cycle
enddef;
%

  pickup pencircle scaled 2bp;
  i = 1;
  forever:
    exitunless (i <=  nb_vectors);
    intersect := false;
    random_length := u*(2+uniformdeviate(1));
    random_angle := uniformdeviate(359);
    random_origin := u*(uniformdeviate(wd*nb_vectors),
uniformdeviate(wd*nb_vectors));
    random_color := (uniformdeviate(1), uniformdeviate(1),
uniformdeviate(1));
    candidate := random_origin -- (random_origin +
random_length*dir(random_angle));
    j := 1;
    forever:
      exitif (j = i) or (intersect = true);
      if bb(random_vector[j]) intersectiontimes bb(candidate) <>  (-1, -1):
        intersect := true;
      fi;
      j := j+1;
    endfor;
    if intersect = false:
      random_vector[i] = candidate;
      drawarrow candidate withcolor random_color;
      freelabel(btex $v$ etex, point .5 of candidate, point .5 of candidate
+ dir (random_angle + 90));
      i := i+1;
    fi;
  endfor;
\stopMPcode


\stoptext

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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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archive  : http://foundry.supelec.fr/projects/contextrev/
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___________________________________________________________________________________