My 1st sonic pi experiment

AmbientExperiment2

#sonic pi
#a piece inspired from Ambien Experiment code by Darin Wilson

#a is the array, i is the previous index. returns a new index in a, in probability close to i.
#The distance is abs(i - j)
#never mind...it just help me remember what the function does
def perlin(a, i)
  #create array with probabilities as a function of distance
  #the indexes of this new array represent distances from i
  a2 = Array.new(a.length){|index| Math.exp(a.length - index)}
  a2[0] = 0

  #assign probabilities in new array based on distances
  #the indexes of this array represent the indexes in the original array (a)
  a3 = a.each_with_index.map { |e, index| a2[(i - index).abs] }
  s = a3.inject(:+)
  a3.map! {|e| e.to_f / s}

  #cumulative probas
  cumsum = 0
  a3.map!{|e| cumsum += e}

  #generate uniform random number
  u = rand(1.0)

  a3.index{|e| e >= u}

end

use_random_seed(0)

use_synth :hollow
with_fx :reverb, mix: 0.7 do

  i1 = 0
  notes1 = [:D2, :E2, :A2, :As2]

  s = [4, 6, 8].choose

  live_loop :note1 do
    play notes1[i1], attack: s/2+1, release: s/2+1
    sleep s
    i1 = perlin(notes1, i1)
    s = [4, 6, 8].choose
  end

  i2 = 0
  notes2 = [:D4, :E4, :A4, :As4, :D5, :E5]

  live_loop :note2 do
    i2 = perlin(notes2, i2)
    play notes2[i2], attack: s/2+1, release: s/2+1
    sleep s
  end

  i3 = 0
  notes3 = [:D3, :D3, :E3, :E3, :A3, :A3, :As3]

  live_loop :note3 do
    i3 = perlin(notes3, i3)
    play notes2[i3], attack: 0.5, release: 3.75, cutoff:90, amp:0.5
    sleep s
  end

end