norm .nf .IS ...minx -1.5 ...maxy 1.5 ...maxx 1.5 ...miny -1.5 ...libfile hole gridline { var a,b; var neg, pos; conn 0.5*(a+b) - neg to 0.5*(a+b) + pos; } main{ conn (1,0) to (1,-1) using 10 gridline {neg = 1; pos = 0;} <a,b>; conn (0,-1) to (1,-1) using 10 gridline {neg = 0; pos = (0,1);} <a,b>; put hole{ radius = 1; center = (0,0); opaque exterior; }; } .IE .IS ...forget gridline .IE