書き初め

a.rb

INPUT_FILE, OUTPUT_FILE = *ARGV
OUTPUT_SIZE = 500
HALF_SIZE = OUTPUT_SIZE / 2

files = []
direction = 0
while direction < 45
  key_file = "direction-#{direction}.gif"
  files.push key_file
  system "convert #{INPUT_FILE} -set option:distort:viewport #{OUTPUT_SIZE}x#{OUTPUT_SIZE}-#{HALF_SIZE}-#{HALF_SIZE} -virtual-pixel tile  -distort Arc '45 #{direction} 50' +repage #{key_file}"
  direction += 9
end

system "convert -coalesce -background white -alpha remove Background -background white -loop 0 -delay 3 #{files.join(' ')} #{OUTPUT_FILE}"

files.each{|file|
  File.unlink(file)
}