Yes, I meant cornered.

But it turns out it works worse in my case, I get paths with hundreds of segments and a run that goes amok. But that made me find a mistake in my code and now I’m using my own again and it works fine:

vardef softenPath( expr hardPath) =
  save softPath; path softPath;
  save len; len := length hardPath;
  save rounding; rounding := 5;
  save i;
  for i=0 upto len:
    if (i=0):
      % first pair
      softPath := point i of hardPath;
    elseif (i=len):
      % lastpair
      softPath := softPath -- point i of hardPath;
    else:
      % intermediate pair
      save subOne; path subOne; subOne := subpath(i-1, i) of hardPath;
      save subTwo; path subTwo; subTwo := subpath(i, i+1) of hardPath;
      save lenOne; numeric lenOne; lenOne := arclength subOne;
      save lenTwo; numeric lenTwo; lenTwo := arclength subTwo;
      save pointOne, pointTwo; pair pointOne, pointTwo;
      pointOne := point (arctime (lenOne-rounding) of subOne) of subOne;
      pointTwo := point (arctime rounding of subTwo) of subTwo;
      save dirOne, dirTwo; pair dirOne, dirTwo;
      dirOne := direction (arctime (lenOne-rounding) of subOne) of subOne;
      dirTwo := direction (arctime (rounding) of subTwo) of subTwo;
      softPath := softPath -- pointOne{dirOne} .. {dirTwo}pointTwo;
    fi
  endfor;
  softPath
enddef;

Fixed rounding of 5bp, but that is easy to change.

> On 5 Apr 2020, at 12:37, Wolfgang Schuster <wolfgang.schuster.lists@gmail.com> wrote:
> 
> Gerben Wierda schrieb am 05.04.2020 um 12:31:
>> I think I saw a function in MetaFun somehwre that you could give a ‘hard’ path, i.e. (0,0) -- (0,1) — (1,1) and it would become a path with nicely rounded (part of a circle) corners (still straight lines), but I can’t find it anymore. I wrote my own, but it is giving me headaches so I’d like to find something that is better than what I produce.
> 
> You you mean "cornered ..." or "smoothed ..."?
> 
> Wolfgang