Neco do metapostu

[pustofkj at inf.upol.cz]

Zdravim,... mam problem, v metapostu chci postupne vytvorit obrazek,...
dam tedy:
picture pic, pic1, pic2, pic3;
pic1:=nullpicture;
addto pic1 .........;

pic2:=mullpicture;
addto pic2 .........;

pic:=nullpicture;
addto pic also pic1;
addto pic also pic2;
addto pic also pic3;

a ted je tu ten problem... pic3 by mel vypadat nejak takto:
pair a, b, c, d;
numeric s;
a := (25mm,0);
b := (0,50mm);
c := (-25mm,0);
d := (0,-50mm);
s := 0.6;
superellipse(a,b,c,d,s);
a mel by byt vybarveny zlute... kdyz ale dam "addto pic3 contour
superellipse(a,b,c,d,s);", tak to haze bug, nehlede na to, ze to chci
vyplnene tou zlutou barvou... jak na to, aby to vse fungovalo tak jak ma?
Dekuji.