# Lesson 14

# Scales Lesson. In this lesson,
# you will use programming features
# to create and manipulate major and
# minor scales.

# General Instructions:
#
# This lesson contains two examples and
# two exercises (A, B).
#
# To listen to an example, change "comment"
# to "uncomment" on the "comment do" line,
# then click the "Run" menu command at the
# top of the Sonic Pi editor window.
# When you are done with the example, turn
# it off by changing "uncomment" back to
# "comment," and move on to the next section
# of the lesson.
#

# Normally, Sonic Pi runs lines and blocks of
# code one after the other in sequence.
# However, in music we often want to play
# several different things at the same time.
# Threads allow us to do this. Creating a
# thread allows the code within the thread to
# start at exactly the same time as any code
# follows.

# Example 1: Major scales using threads.

comment do
  use_bpm 100
  use_synth :piano
  # C Major Scale
  scale_ring = (ring :C4, :D4, :E4, :F4, :G4,
                    :A4, :B4, :C5)
  index = 0
  #create a metronome in 4/4
  in_thread do
    loop do
      2.times do
        sample :drum_heavy_kick
        sleep 1
        sample :perc_snap
        sleep 1
      end
    end
  end
  in_thread do
    loop do
      note = scale_ring[index]
      play note
      sleep 0.5
      index += 1
    end
  end
  use_synth :dsaw
  new_index = 7
  loop do
    note = scale_ring[new_index]
    play note
    sleep 0.5
    new_index -= 1
  end

end

# Exercise A
# 1) Change the C Major scale in scale_ring
#    (Example 1) to:
#     a) G major
#     b) D major
#     c) A major
#     d) E major
#     e) F major
#     f) Bb major
#     g) Eb major
#     h) Ab major

#  2) Change the second scale-playing loop
#     (after the second thread) to:
#     a) play the same scale in the same direction
#        as in the seconds thread, but a 3rd higher.
#     b) play the same scale in the same direction
#        as in the second thread, but a 6th lower.

# Example 2: Minor scales using threads.

comment do
  use_bpm 100
  use_synth :piano
  # C natural minor scale
  scale_ring = (ring :C4, :D4, :Eb4, :F4, :G4,
                    :Ab4, :Bb4, :C5)
  index = 0
  #create a metronome in 4/4
  in_thread do
    loop do
      2.times do
        sample :drum_heavy_kick
        sleep 1
        sample :perc_snap
        sleep 1
      end
    end
  end
  loop do
    note = scale_ring[index]
    play note
    sleep 0.5
    index += 1
  end
end

# Exercise B
# 1) Change the minor scale form in the
#    loop that plays after the first thread
#    (Example 2) in the following way:
#   a) Create harmonic minor ascending by
#      using an if conditional on the index
#      of the note to be played, and change the
#      note accordingly.
#      TIP: evaluate the index by using the
#           the modulo operator %
#               (index-target) % length = 0
#           where index is the current index,
#           target is the index of the note to
#           change, and length is the total
#           number of notes in the ring.
#           The modulo operator gives the
#           remainder of the division of
#           the first term by the second term.
#           Examples of % operator:
#             3 % 2 = 1
#             3 % 3 = 0
#             5 % 3 = 2
#             6 % 3 = 0
#           Examples of (index-target) % length = 0
#             length = 8
#             target = 4
#             index = 4, (4 - 4) % 8 = 0
#             index = 12, (12 - 4) % 8 = 0
#             index = 20, (20 - 4) % 8 = 0
#   Note that index = 4 will not give you the
#   harmonic minor scale! You will need to use
#   the correct index.