tess 4 f 0.3 0.3 0.3 1 1 # a centered sphere s 0 0 0 5 s 20 0 0 5 s 40 0 0 5 s 60 0 0 5 f 1 1 1 1 1 s -5 0 0 3 s 0 5 0 3 s 0 -5 0 3