--Copyright The Numerical Algorithms Group Limited 1994.
--the first attempt
drawRibbons(flist,xrange) ==
  sp := createThreeSpace()
  y0 := 0
  for f in flist repeat
    makeObject(f,xrange,y=y0..y0+1,
       space==sp, var2Steps ==1)
    y0 := y0+1
  vp:=makeViewport3D(sp,"Ribbons")
  drawStyle(vp,"shade")
  outlineRender(vp,"on")
  showRegion(vp,"on")
  n := # flist
  zoom(vp,n,1,n)
  rotate(vp,0,75)
  vp
