generate moving gifs from any 64x64 pic

chian-go-down.fish

function dir-opt
  set fmt
  set sig
  switch $argv[1]
    case left
      set fmt "+%d+0"
      set sig '(-1)'
    case right
      set fmt "+%d+0"
      set sig 1
    case up
      set fmt "+0+%d"
      set sig '(-1)'
    case down
      set fmt '+0+%d'
      set sig 1
  end
  set frame $argv[2]
  set trans (echo "$sig * ($frame * 32 / 6)" | bc)
  printf $fmt $trans
end

set dirs left right up down

if [ (count $argv) != 1 ]
  echo "usage : this-script image-of-64x64"
  exit 1
else
  set image $argv
  for from in $dirs
    for to in $dirs
      mkdir "$from-$to"
      for i in (seq 0 11)
        set j (echo "$i - 12" | bc)
        convert -size 64x64 xc:white \
          $image -geometry (dir-opt $to $i) -composite \
          $image -geometry (dir-opt $from $j) -composite \
          $from-$to/frame-$i.gif
      end
      convert -delay 6 -dispose background $from-$to/frame-*.gif -loop 0 $from-$to/$from-$to.gif
    end
  end
end