Antoine's Necklace code in G'MIC

antoine :
  R=1
  N=18
  -ss3d 0.3 -m3d 5 -db3d 0 -md3d -1
  -torus3d 1,0.3
  -repeat 4,scale
    -repeat $N
      ang={$>*360/$N}
      --r3d[0] 0,1,0,{90*$>%2} -+3d. {4*$R},0,0 -r3d. 0,0,1,$ang
      col={${-math_lib};hsv2rgb([$ang,1,1])}
      -if {!$scale} -col3d. $col -else -l. -s3d -+[4] '$col' -/[4] 2 -a y -endl -endif
    -done
    -rm[0]
    -+3d
    R*=4
    --r3d. 1,0,0,-40 -snapshot3d. 1024,1,0,0,0,0 -on. antoine.png -rm.
  -done