blues.rb

CHORDS_BASE =    [:C2, :C2, :C2, :C2, :F2, :F2, :C2, :C2, :G2, :F2, :C2, :C2]
CHORDS_HARMONY = [:C3, :C3, :C3, :C3, :F3, :F3, :C3, :C3, :G3, :F3, :C3, :C3]
BLUES_SCALE = [:C4, :Eb4, :F4, :Gb4, :G, :Bb4, :C5]

FOURTH = 0.5
EIGHTH = FOURTH / 2
SIXTEENTH = EIGHTH / 2

def generate_rhythms(candidates=[EIGHTH, FOURTH], remaining_time=FOURTH*4)
  rhythms = []
  
  while remaining_time > candidates.min
    rhythm = choose(candidates)
    rhythms << rhythm
    remaining_time -= rhythm
  end
  
  rhythms << remaining_time if remaining_time > 0
  
  # Generate Swing Pattern
  (rhythms.length - 1).times do |i|
    if rhythms[i] == EIGHTH and rhythms[i + 1] == EIGHTH
      rhythms[i] = EIGHTH + SIXTEENTH
      rhythms[i + 1] = EIGHTH - SIXTEENTH
    end
  end
  
  rhythms
end

live_loop :bass_line do
  use_synth :fm
  
  CHORDS_BASE.each do |c|
    notes = chord(c, '9').to_a
    
    rhythms = generate_rhythms
    
    play notes[0], release: rhythms[0]
    sleep rhythms[0]
    
    rhythms[1..-1].each do |t|
      play choose([notes[1], notes[3], notes[4]]), release: t
      sleep t
    end
  end
end

live_loop :chord do
  use_synth :fm
  
  CHORDS_HARMONY.each do |c|
    notes = chord(c, '9').to_a
    rhythms = generate_rhythms
    
    rhythms.each do |t|
      play [notes[1], notes[3], notes[4]], release: t if choose([true, false])
      sleep t
    end
  end
end

melody_reverse = false
live_loop :melody do
  use_synth :beep
  
  rhythm = generate_rhythms([FOURTH * 2, FOURTH, EIGHTH, SIXTEENTH], remaining_time=FOURTH*8)
  scale_notes = BLUES_SCALE
  scale_notes = scale_notes.reverse if melody_reverse
  melody_reverse = !melody_reverse
  
  rhythm.each_with_index do |t, i|
    offset = choose([-2, -1, 1, 2])
    
    new_index = (i.to_f / rhythm.length).to_i + offset
    new_index = 0 if new_index < 0
    new_index = scale_notes.length - 1 if new_index >= scale_notes.length
    
    note = scale_notes[new_index]
    play note, release: t if rrand(0, 1) < 0.9
    sleep t
  end
end