Re: shading box many times

[Vit Zyka <vit.zyka@seznam.cz>]

Taco Hoekwater wrote:
> Hans Hagen wrote:
> 
>> Vit Zyka wrote:
>>
>>> Dear Metafun Wizards,
>>>
>>> I have noticed some strange behaviour with box shading. It works OK 
>>> until some number of shadings. Please see example:
>>>   http://typokvitek.com/tmp/shade-many.pdf
>>> Any idea for solving? Next not-minimal but small and illustrative 
>>> example can help.
>>
>>
>> works ok here; since it concerns independent mp runs, i cannot imagine 
>> what goes wrong; mayeb a bad random numer; does your log say something?
> 
> 
> My results are the same as Vit's example: The last 9 items are
> not shaded but have 3 black sides and 1 white one
> (with \write18 disabled, using a single \jobname-mpgraph.mp)
> 
> I don't know what is going, but at least I can reproduce the problem.
> I'm attaching an example wrong image.
> 
> Taco

A minimal version is here. It shows the randomization is not the reason. 
Shade disappears at 989th shade.

=======================================
\startuseMPgraphic{F}
   def log(expr Xstart, Xstop)=
   begingroup
     save x, y, D, w, P;
     pair D;
     path P;
     w := 2.5pt; w := w/2;
     D := unitvector(Xstop-Xstart) rotated 90;
     z1 = Xstart shifted (w*D);
     z2 = Xstop shifted (w*D);
     z3 = Xstop shifted (-w*D);
     z4 = Xstart shifted (-w*D);
     P := z1--z2{z2-z1}..{z4-z3}z3--z4{z4-z3}..{z2-z1}cycle;
     P
   endgroup
   enddef;

   path P;
   x11 = 0;
   x12 = \overlaywidth;
   y11 = y12 = \overlayheight;
   P:= log(z11,z12); linear_shade(P,8,(1,1,1),(0,0,0)); draw P;
\stopuseMPgraphic

\defineoverlay[F][\uniqueMPgraphic{F}]
\defineframed[F][offset=2mm,strut=yes,background=F,frame=off]

\starttext
   \noindent\dorecurse{1000}{\F{\recurselevel} }
\stoptext
============================================