Oh, cool. I've found some info in the Metafun manual too. I should read more carefully next time.
Thank you very much!

Jairo :)

El mar., 3 de nov. de 2020 a la(s) 07:29, Hans Hagen (j.hagen@xs4all.nl) escribió:
On 11/3/2020 12:59 PM, Jairo A. del Rio wrote:
> Hi everyone. I want to know if nowadays (2020) Metafun is able to do an
> actual unfill, like above:
>
> https://tex.stackexchange.com/questions/151068/how-can-i-fill-a-complex-path-with-metapost-metafun/218718#218718
>
> Example of what I want to do:
>
> \startMPpage
>
> path A, B, C;
>
> A := unitcircle shifted (-center unitcircle);
>
> A := A scaled 4cm;
>
> B := unitcircle shifted (-center unitcircle);
>
> B := B scaled 1cm;
>
> %C := (reverse B) shifted (left*1.4cm);
>
> %It works for two paths
>
> fill (reverse B)-- A -- cycle withcolor red;
>
> %fill A -- (reverse B) -- C -- cycle withcolor red;
>
> %When I try the same with three paths, a thin, unwanted line appears
>
> \stopMPpage
>
> I'm aware of unfill and I've read somewhere else about using pens
> instead, but I want to know if a better solution is possible. Thank you
> in advance.
     \startMPpage
         path A; A := (unitcircle shifted (-center unitcircle)) scaled 4cm;
         path B; B := (unitcircle shifted (-center unitcircle)) scaled 1cm;
         path C; C := B shifted (left*1.4cm);

         nofill A; nofill B; eofill C;
     \stopMPpage

to be wikified

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