quick and dirty procedural island generation

procgen.rb

class String
  def rgb(r,g,b, bg=false) "\033[#{bg ? 48 : 38};5;#{ 16 + 36 * (r/43) + 6 * (g/43) + (b/43) }m#{self}\033[0;00m" end
end

PALETTE = [0x279faf, 0x3ec2d9, 0x86cfd6, 0xc2dcd1, 0xebd8b8, 0xd9be93, 0xc6a16d, 0xa07644, 0x74a044, 0x2e7f21, 0x440044, 0xff0000].map{|c|
          [(c & 0xff0000) >> 16, (c & 0x00ff00) >> 8, c & 0x0000ff]}

def show(m, w=nil, h=nil, pal=PALETTE)
  (w0,wn),(h0,hn) = m.keys.minmax_by(&:first).map(&:first), m.keys.minmax_by(&:last).map(&:last)
  arr = []
  (w0..wn).each do |x|
    line = []
    (h0..hn).each do |y|
      line << (m[[x,y]] == 11 ? 'X' : ' ').rgb(*pal[m[[x,y]]], true)
    end
    arr << line
  end
  puts arr.map(&:join).join("\n")
end

def neighbors(m,x,y)
  [[-1,-1],[-1,0],[-1,1],[0,-1],[0,1],[1,-1],[1,0],[1,1]].map{|dx,dy| [m[[dy+x,dy+x]], [dx+x, dy+y]] }
end

def ncount(m,x,y)
  neighbors(m,x,y).count{|e,xy| e > 0}
end

def lake_maker(m, xy, opts={})
  opts[:lake_iterations] ||= 3
  m[xy] /= 2
  neighbors(m,*xy).sample(opts[:lake_neighbor_samples]||3, random: opts[:prng]||Random.new).each do |val, nxy|
    m[nxy] /= 2
    if opts[:lake_iterations] > 0
      o = opts.dup
      o[:lake_iterations] -= 1
      m = lake_maker(m, nxy, o)
    end
  end
  m
end

def gen(opts={})
  w,h = opts[:w] || 64, opts[:h] || 64
  r = Random.new(opts[:seed]||rand(99999))
  m = Hash.new(0)
  (opts[:land_seeds]||4).times{ m[[r.rand(h), r.rand(w)]] = 1 }
  (opts[:land_iterations]||20).times do
    _m = m.dup
    m.keys.each do |x,y|
      if ncount(m,x,y) < 3
        _m[[x,y]] += 1 if _m[[x,y]] < 10.times.map{|e| 9-(e**2)/10}.sample(random: r)
        neighbors(m,x,y).sample(2, random: r).each do |v,xy|
          _m[xy] += 1 if _m[xy] < 4
        end
      end
    end
    m = _m
  end
  # generate lakes
  (opts[:lake_seeds]||4).times do
    begin
      xy = m.keys.sample(random: r)
    end while m[xy] < 6
    m = lake_maker(m, xy, opts.merge(pnrg: r))
  end

  way_makers = [[[-1,0],[0,-1],[0,1]], [[-1,0],[0,-1],[1,0]], [[1,0],[0,1],[0,-1]], [[1,0],[0,1],[-1,0]]]
  # generate rivers
  (opts[:river_seeds]||4).times do
    xy = m.keys.sample(random: r)
    ds = way_makers.sample(random: r)
    loop do
      d = ds.sample(random: r)
      xy = [xy[0]+d[0], xy[1]+d[1]]
      break if m[xy] == 0
      m[xy] /= 3
    end
  end
  # generate treasure and path
  begin
    xy = m.keys.sample(random: r)
  end while m[xy] < 6
  m[xy] = 11
  ds = way_makers.sample(random: r)
  loop do
    d = ds.sample(random: r)
    xy = [xy[0]+d[0], xy[1]+d[1]]
    break if m[xy] == 0
    m[xy] = 10 unless m[xy] == 11
  end
  m
end

seed = (ARGV[0]||rand(9999)).to_i
show(gen(w:256, h:64, land_seeds:10, lake_neighbor_samples:2, lake_iterations:6, river_seeds:8, land_iterations:25, seed:seed))
puts seed