create an array of a gif animation with random start offsets.

jelly.rb

# cat jelly spreader
require 'chunky_png'

tile_count_width  = 20
tile_count_height = 10
tile_count = tile_count_width + tile_count_height

# load frames

print "Loading frames..."

frame_image_names = Dir.glob("rolls/*.png").sort
frame_images = []

frame_image_names.each do |name|
  frame_images.push ChunkyPNG::Image.from_file name
end

print "done!\n"

frame_count = frame_images.length
puts "#{frame_count} frames!"

# create matrix of starting offsets (and flips)

print "Randomizing rolls..."

frame_infos = Array.new(tile_count_width) { Array.new(tile_count_height) { Hash.new } }

frame_infos.each_with_index do |frame_width_row, width_index|
  frame_width_row.each_with_index do |frame_info, height_index|
    frame_info['offset'  ] = Random.rand frame_count
    frame_info['flipped' ] = [true, false].sample
    frame_info['w_offset'] = width_index * frame_images.first.width
    frame_info['h_offset'] = height_index * frame_images.first.height
  end
end

print "done!\n"


# paste in frame offsets into each master frame

print "Rolling around...\n"

frame_width  = tile_count_width  * frame_images.first.width
frame_height = tile_count_height * frame_images.first.height

frame_count.times.each do |master_frame_index|

  puts "#{frame_width}x#{frame_height}[#{master_frame_index}] roll space"
  rollyspace = ChunkyPNG::Image.new frame_width, frame_height, ChunkyPNG::Color::TRANSPARENT


  frame_infos.each do |frame_width_row|
    frame_width_row.each do |frame_info|
      image_x = frame_info['w_offset']
      image_y = frame_info['h_offset']

      frame_offset = (frame_info['offset'] + master_frame_index) % frame_count
      image = frame_images[frame_offset]

      if frame_info['flipped'] == true
        rollyspace.compose! image.flip_vertically, image_x, image_y
      else
        rollyspace.compose! image, image_x, image_y
      end
    end
  end

  rollyspace.save("masterroll/rool#{'%02d' % master_frame_index}.png");
end

print "done!\n"