Sonic Pi Chord Generation 2 (now with secondary dominants and modal interchange)

chords2.rb

# MIDI Chord generation
# Now with modal interchange and secondary dominants
# See https://www.youtube.com/watch?v=3yryQbRgsGo

define :oneChord do | tonic, mode, deg |
  majorKeyTriads = [:M,:m,:m,:M,:M,:m,:dim]
  minorKeyTriads = [:m,:dim,:M,:m,:m,:M,:M]
  majorKey7s = [:M7,:m7,:m7,:M7,:dom7,:m7,:halfdiminished]
  minorKey7s = [:m7,:halfdiminished,:M7,:m7,:m7,:M7,:dom7]
  
  # Modal interchange (negative numbers major <-> minor)
  if deg < 0 then
    return oneChord(tonic,(mode=="major") ? "minor" : "major",-deg)
  end
  
  case deg
  when 1..7 # Simple Triads
    root = degree(deg,tonic,mode)
    lookup = (mode == "major") ? majorKeyTriads : minorKeyTriads
    theChord = chord(root,lookup[deg-1])
  when 71..77 # Seventh Chords
    deg = deg - 70
    root = degree(deg,tonic,mode)
    lookup = (mode == "major") ? majorKey7s : minorKey7s
    theChord = chord(root,lookup[deg-1])
  when 21..27 # Secondary dominants
    deg = deg - 20
    original_root = degree(deg,tonic,mode)
    root = degree(5,original_root,mode)
    theChord = chord(root,:dom7)
  end
  return theChord
end

define :chordSeq do | tonic, mode, degs |
  
  cs = []
  
  degs.each { | deg |
    theChord = oneChord(tonic,mode,deg)
    cs.append [tonic,mode,theChord]
  }
  cs
end

use_bpm 96

live_loop :piano do
  #cs = chordSeq(:C3,"minor",[1,76,4,75, 5,7,74,5,
  #                           1,76,4,75, 5,7,74,1])
  #cs = chordSeq(:C3,"major",[1,24,4,26,6,25,5,21])
  cs = chordSeq(:C3,"major",[
                  71,6,23,73,
                  4,-4, 75, 75,
                  -76, -73, 1, 1
  ])
  
  cs.each {| xs |
    tonic,mode,c = xs
    
    c.each {|cn| midi_note_on cn, 90, channel: 1,
    port: "loopbe_internal_midi_1" }
    
    sleep 2
    c.each {|cn| midi_note_off cn, channel: 1,
    port: "loopbe_internal_midi_1"}
    
    n = c.choose+12
    midi n, 90, channel: 1,
    port: "loopbe_internal_midi_1"
    sleep 0.5
    
    midi n, 90, channel: 1,
    port: "loopbe_internal_midi_1"
    sleep 0.5
    
    n = c.choose+24
    midi n, 90, channel: 1,
    port: "loopbe_internal_midi_1"
    sleep 0.5
    
    midi scale(tonic,mode).choose+24, 80,
    channel: 1,
    port: "loopbe_internal_midi_1"
    
    sleep 0.5
  }
end