watch a directory for blender project files and render the default scene if one appears

gistfile1.rb

#!/usr/bin/ruby
require 'directory_watcher'
require 'ftools'

FOLDER = './render-queue'
#THREADS = 8
#BLENDER = '/usr/bin/blender'
BLENDER = '/Applications/blender/blender.app/Contents/MacOS/blender'

def randomFileName (numberOfRandomchars)
  s = ""
  numberOfRandomchars.times { s << (65 + rand(26))  }
  return s
end

def uniqueDir (dir)
  return !File.exists?("#{FOLDER}/render/#{dir}")
end

File.makedirs("#{FOLDER}/render") unless File.exists?("#{FOLDER}/render")

dw = DirectoryWatcher.new FOLDER, :glob => '**/*.blend', :pre_load => true
dw.interval = 2.0
dw.stable = 2 #making sure the file is fully synced

puts "watching #{FOLDER} for Blender project files."
dw.add_observer do |*args| 
  args.each do |event| 
    if event.type == :stable
        outdir = 'RENDER'
        until uniqueDir(outdir)
          outdir = randomFileName(5)
        end
        cmd = "#{BLENDER} -b #{event.path} -f 1 -o #{FOLDER}/render/#{outdir}/"
        puts "rendering #{event.path}"
        system(cmd) #render
        File.unlink(event.path) #remove the .blend file after rendering
     end
  end
end

dw.start
gets      # when the user hits "enter" the script will terminate
dw.stop