beginfig(28); path p[]; p1 = fullcircle scaled .6in; z1=(.75in,0)=-z3; z2=directionpoint left of p1=-z4; p2 = z1..z2..{curl1}z3..z4..{curl 1}cycle; fill p2 withcolor .4[white,black]; unfill p1; draw p1; transform T; z1 transformed T = z2; z3 transformed T = z4; xxpart T=yypart T; yxpart T=-xypart T; picture pic; pic = currentpicture; for i=1 upto 2: pic:=pic transformed T; draw pic; endfor dotlabels.top(1,2,3); dotlabels.bot(4); endfig; end.