# animation file for the zipper
perm
line .5;0;.5;.5;$GREEN;5
trans
# here is the track
line .5+xt[0..15]/s;.5+yt[j]/s;.5+xt[j+1]/s;.5+yt[j+1]/s;$BLACK;2
line .5+xc/s;.5+yc/s;.5+xp/s;.5+yp/s
fcircle .5+xc/s;.5+yc/s;.015;$RED
fcircle .5+xp/s;.5+yp/s;.02;$BLUE
end