I have just noticed Thomas Holders  metapost sample for hiding small rocks at large scale reductions. http://therion.speleo.sk/wiki/doku.php?id=metapost

  def l_rockborder (expr p) =
    if abs(llcorner p - urcorner p) > u:
      l_rockborder_UIS(p);
    fi;
  enddef;

I’m guessing the same approach could be used to hide any type of line or area object dependant on the scale, and it looks as though it might be trivially easy to implement, even for someone like me who knows next to nothing about meta post.

What would be the chances of this working in the form presented above for point objects?

Or for labels as below?

  def p_label (expr txt,pos,rot,mode) =
    if abs(llcorner p - urcorner p) > u:
      p_label_UIS(txt,pos,rot,mode);
    fi;
  enddef;

Or modified to show or hide point objects depending on the value of the –scale property?

Has anyone tried something like this?

Bruce