generate flat map chunks for easy testing (minecraft alpha server)

flatten.rb

#!/usr/bin/env ruby

require "fileutils"
require "pathname"
require "zlib"

world = Pathname.new File.expand_path("./world")

0.upto(3) do |x|
  0.upto(3) do |z|
    out = ""
    out << [10, 0, 10, 5, "Level"].pack("cncna5")

    block_data = [7, 4, "Data", 16384] + [0] * 128 * 256
    out << block_data.pack("cna4Nc16384")

    out << [9, 8, "Entities", 10, 0].pack("cna8cN")

    last_update = 0
    big = last_update >> 32
    little = last_update - (last_update >> 32 << 32)
    out << [4, 10, "LastUpdate", big, little].pack("cna10NN")

    out << [3, 4, "xPos", x].pack("cna4N")
    out << [3, 4, "zPos", z].pack("cna4N")

    out << [9, 12, "TileEntities", 10, 0].pack("cna12cN")
    out << [1, 16, "TerrainPopulated", 1].pack("cna16c")

    # sky_light = [0] * 64 + [240] + [255] * 63
    sky_light = [0] * 32 + [255] * 32
    sky_light = [7, 8, "SkyLight", 16384] + sky_light * 256
    out << sky_light.pack("cna8NC16384")

    heights = [7, 9, "HeightMap", 256] + [64] * 256
    out << heights.pack("cna9NC256")

    block_light = [0] * 128
    block_light = [7, 10, "BlockLight", 16384] + block_light * 256
    out << block_light.pack("cna10NC16384")

    column = [7, 7, 7, 7, 7] + [3] * 58 + [2] + [0] * 64
    blocks = [7, 6, "Blocks", 32768] + column * 256
    out << blocks.pack("cna6Nc32768")

    # close out the Level and "" complex entities
    out << [0, 0].pack("cc")

    fn = world + "#{x}/#{z}/c.#{x}.#{z}.dat"

    puts "writing #{fn}..."
    Zlib::GzipWriter.open(fn) { |gz| gz << out }
  end
end