# render some spheres:
src_dst 0 0
   src_blend 0
   spheres 3 0.2
   map_range 0.01 1 1 0.01
   map_range 0.5 0.89 0 0 # map away some inner parts

src_dst 1 1
   menger_sponge 2

src_dst 1 0
   src_range 0 0
   fill 0

#  show_range_sector_type C1 1