Standard 12 bar blues (bass line + comping) for sonic pi (sonic-pi.net)

sonic_pi_feeling_blue.rb

# Standard 12 bar blues
# I7  | IV7  | I7 | I7
# IV7 | IV7 | I7 | I7
# V7  | IV7 | I7 | I7

# Choose a root note (one) and everything else will fall into place.
one = :G2
four = one + 5
five = one + 7

# Groove: quarter note triplets (trip-uh-let, trip-uh-let, ...)
trip_uh = 0.6666
let = 0.3333

chord_progression = [
  one, four, one, one,
  four, four, one, one,
  five, four, one, one
]

in_thread(name: :bass) do
  chord_progression.each do |note|
    bass_line note
  end
end

in_thread(name: :comp) do
  chord_progression.each do |note|
    comp_line note
  end
end

define :bass_line do |root|
  cue :tick
  [root, root + 9, root + 10, root + 9].each do |note|
    play note, release: trip_uh
    sleep trip_uh
    play root + 7, amp: 0.5, release: let, amp: 2
    sleep let
  end
end

define :comp_line do |root|
  sync :tick
  root_8va = root + 12
  play chord(root_8va, :dom7), release: trip_uh, amp: 12
  sleep trip_uh
  play chord(root_8va, :dom7), release: let, amp: 8
  sleep let + 3
end

Thanks for sharing!!

I moved :comp_line to line 21 because is called on line 29 before definition.