Combines all Minecraft map .dat files found in the same directory as the script. TODO: add coord grid system

map_collector.rb

require 'chunky_png'
require 'nbtfile'

COLOR_MAP = %q{
  255,255,255
  255,255,255
  255,255,255
  255,255,255

  89,125,39
  109,153,48
  127,178,56
  109,153,48

  174,164,115
  213,201,140
  247,233,163
  213,201,140

  117,117,117
  144,144,144
  167,167,167
  144,144,144

  180,0,0
  220,0,0
  255,0,0
  220,0,0

  112,112,180
  138,138,220
  160,160,225
  138,138,220

  117,117,117
  144,144,144
  167,167,167
  144,144,144

  0,87,0
  0,106,0
  0,124,0
  0,106,0

  180,180,180
  220,220,220
  255,255,255
  220,220,220

  115,118,129
  141,144,158
  164,168,184
  141,144,158

  129,74,33
  157,91,40
  183,106,47
  157,91,40

  79,70,70
  96,96,96
  112,112,112
  96,96,96

  45,45,180
  55,55,220
  64,64,255
  55,55,220

  73,58,35
  89,71,43
  104,83,50
  89,71,43
}.split("\n").map(&:strip).reject{|line| line.empty?}

class MapCollector
  attr_reader :mc_data, :west_border, :east_border, :north_border, :south_border
  
  def initialize(map_dir = '.')
    @map_dir = map_dir
    @mc_data = []
    Dir.foreach(map_dir) do |f|
      next unless f =~ /\.dat$/
      
      @mc_data << NBTFile.load(File.read("./#{f}"))[1]['data']
    end
    raise "Could not find any map data files in this folder" if @mc_data.empty?
    
    east_west   = mc_data.collect { |f| rounded(f['xCenter']) }
    north_south = mc_data.collect { |f| rounded(f['zCenter']) }
    
    # Determine the edges of our maps
    @west_border = east_west.min - 512
    @east_border = east_west.max + 512
    @north_border = north_south.min - 512
    @south_border = north_south.max + 512
  end
  
  def render_map
    new_map = ChunkyPNG::Image.new(self.width, self.height, ChunkyPNG::Color::TRANSPARENT)
    mc_data.each do |data|
      data['colors'].split('').each_with_index do |pixel, i|
        next if pixel.ord <= 3
        
        x_image_pixel = world_coord(data, i)[0] - self.west_border
        y_image_pixel = world_coord(data, i)[1] - self.north_border
        
        8.times do |x_offset|
          8.times do |y_offset|
            new_map[(x_image_pixel + x_offset), (y_image_pixel + y_offset)] = color(pixel.ord)
          end
        end
      end
    end
    
    apply_grid(new_map, mc_data[0])
    
    new_map.save(File.join(@map_dir, 'full_map.png'))
  end
  
  def width
    self.east_border - self.west_border
  end
  
  def height
    self.south_border - self.north_border
  end
  
  def color(ord)
    rgb = (COLOR_MAP[ord] || '0,0,0').split(',').collect { |c| c.to_i }
    ChunkyPNG::Color.rgb(*rgb)
  end
  
  def world_coord(data, pixel)
    world_offset(pixel).zip(map_center(data)).collect { |offset, center| offset + center  }
  end
  
  def world_offset(pixel)
    map_pixel_coord(pixel).collect { |p| (p - 64) * 8 }
  end
  
  def map_pixel_coord(pixel)
    [pixel % 128, pixel / 128]
  end
  
  def map_center(data)
    [rounded(data['xCenter']), rounded(data['zCenter'])]
  end
  
  def rounded(int)
    int / 8 * 8
  end
  
  def apply_grid(map_image, mc_map)
    grid_offsets = map_center(mc_map).collect { |c| grid_interval - (c % grid_interval) }
    
    x_offset = grid_offsets[0]
    while x_offset <= self.width
      map_image.line(x_offset, 0, x_offset, self.height, ChunkyPNG::Color.rgba(0, 0, 0, 128))
      x_offset += grid_interval
    end
    
    y_offset = grid_offsets[1]
    while y_offset <= self.height
      map_image.line(0, y_offset, self.width, y_offset, ChunkyPNG::Color.rgba(0, 0, 0, 128))
      y_offset += grid_interval
    end
  end
  
  def grid_interval
    100
  end
end