# Lesson 2

# Rhythm Lesson. In this lesson, learn to
# convert numerical values into meaningful
# musical rhythms.

# General Instructions:
#
# This lesson contains four 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.
#

# The Sleep Command. Sonic Pi will play all
# notes at once unless the play commands are
# separated by a sleep command. The sleep
# command is the key to creating different
# rhythm patterns.

# Example 1: Three notes play at once (no
# sleep command):

comment do
  play 60
  play 64
  play 68
end

# Example 2: Use the sleep command to insert
# one beat between each note:

comment do
  play 60
  sleep 1
  play 64
  sleep 1
  play 68
end

# Beat: In Sonic Pi a beat = 1. By default, a
# beat lasts for one second, because Sonic Pi
# automatically sets the beats-per-minute value
# to 60. This is the same as setting a metronome
# to 60. (60 beats / minute = 1 beat / second).
# You can change the beat-per-minute value
# with "use_bpm."

# Example 3:

comment do
  use_bpm 120
  play :C
  sleep 1
  play :D
  sleep 1
  play :E
end

# The code in Example 3 sets the beats-per-minute
# to 120, so the beat rate is twice as fast as
# 60 bpm: 120 beats / minute = 2 beats / second

# Exercise A
# Change the bpm value in Example 1 to:
#   1) 100 beats per minute
#   2) 1 beat every 2 seconds
#       (hint: bpm number < 60!)
#   3) 3 beats per second
#       (hint: bpm number > 120!)



# Rhythm Variety.
# In simple meters like 4/4 and 3/4, we usually
# say "the quarter note gets the beat."
# So, for example
#   1 = quarter note
#   2 = half note
#   3 = half note dot
#   4 = whole note
# We can also use fractions and decimals:
#   1.0/2.0 = 8th note
#   1.0/4.0 = 16th note
#   0.5 = 8th note
#   0.25 = 16th note
# [NOTE: in Sonic Pi, fractions smaller than 1
# should use decimal numerators and denominators
# instead of whole numbers. Otherwise the fraction
# will be read as 0.
#
#   Correct:
#             1.0 / 2.0
#             2.0 / 3.0
#             1.0 / 4.0
#             1.0 / 8.0
#
#   Incorrect (will be read as 0):
#             1 / 2
#             2 / 3
#             1 / 4
#             1 / 8
#

# Example 4: Run the sample code below to hear
# a familiar tune. Giving the sleep command
# different beat values changes the rhythm.

comment do
  use_bpm 100
  play 60
  sleep 1
  play 60
  sleep 1
  play 67
  sleep 1
  play 67
  sleep 1
  play 69
  sleep 1
  play 69
  sleep 1
  play 67
  sleep 2
  play 65
  sleep 1
  play 65
  sleep 1
  play 64
  sleep 1
  play 64
  sleep 1
  play 62
  sleep 1
  play 62
  sleep 1
  play 60
  sleep 2
end

# Exercise B
#   1) Change the bpm value in Example 4 so
#      that the tune plays twice as fast.
#   2) Keep the new bpm value from 1), but
#      change the values of the beats in Example
#      4 so that the tune plays twice as slowly;
#      the tune should play at the same speed
#      as the original tempo, even though the
#      bpm is twice as fast.
#      TIP: Instead of changing each beat value
#      directly, you can multiply each beat
#      value by a constant factor. For example,
#      if you wanted to make each beat three
#      times as long:

#               sleep 1 * 3