Class: HeadMusic::Analysis::Motion

Inherits:
Object
  • Object
show all
Defined in:
lib/head_music/analysis/motion.rb

Overview

Motion defines the relative pitch direction of the upper and lower voices of subsequence intervals.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(first_harmonic_interval, second_harmonic_interval) ⇒ Motion

Returns a new instance of Motion.



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# File 'lib/head_music/analysis/motion.rb', line 8

def initialize(first_harmonic_interval, second_harmonic_interval)
  @first_harmonic_interval = first_harmonic_interval
  @second_harmonic_interval = second_harmonic_interval
end

Instance Attribute Details

#first_harmonic_interval ⇒ Object (readonly)

Returns the value of attribute first_harmonic_interval.



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# File 'lib/head_music/analysis/motion.rb', line 6

def first_harmonic_interval
  @first_harmonic_interval
end

#second_harmonic_interval ⇒ Object (readonly)

Returns the value of attribute second_harmonic_interval.



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# File 'lib/head_music/analysis/motion.rb', line 6

def second_harmonic_interval
  @second_harmonic_interval
end

Instance Method Details

#contrapuntal_motion ⇒ Object 



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# File 'lib/head_music/analysis/motion.rb', line 47

def contrapuntal_motion
  i[parallel similar oblique contrary repetition].detect do |motion_type|
    send("#{motion_type}?")
  end
end

#contrary? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/analysis/motion.rb', line 37

def contrary?
  upper_melodic_interval.moving? &&
    lower_melodic_interval.moving? &&
    upper_melodic_interval.direction != lower_melodic_interval.direction
end

#direct? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/analysis/motion.rb', line 22

def direct?
  parallel? || similar?
end

#lower_melodic_interval ⇒ Object (private) 



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# File 'lib/head_music/analysis/motion.rb', line 65

def lower_melodic_interval
  HeadMusic::Analysis::MelodicInterval.new(lower_notes.first, lower_notes.last)
end

#lower_notes ⇒ Object (private) 



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# File 'lib/head_music/analysis/motion.rb', line 73

def lower_notes
  [first_harmonic_interval, second_harmonic_interval].map(&:lower_note)
end

#notes ⇒ Object 



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# File 'lib/head_music/analysis/motion.rb', line 43

def notes
  upper_notes + lower_notes
end

#oblique? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/analysis/motion.rb', line 17

def oblique?
  upper_melodic_interval.repetition? && lower_melodic_interval.moving? ||
    lower_melodic_interval.repetition? && upper_melodic_interval.moving?
end

#parallel? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/analysis/motion.rb', line 26

def parallel?
  upper_melodic_interval.moving? &&
    upper_melodic_interval.direction == lower_melodic_interval.direction &&
    upper_melodic_interval.steps == lower_melodic_interval.steps
end

#repetition? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/analysis/motion.rb', line 13

def repetition?
  upper_melodic_interval.repetition? && lower_melodic_interval.repetition?
end

#similar? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/analysis/motion.rb', line 32

def similar?
  upper_melodic_interval.direction == lower_melodic_interval.direction &&
    upper_melodic_interval.steps != lower_melodic_interval.steps
end

#to_s ⇒ Object 



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# File 'lib/head_music/analysis/motion.rb', line 53

def to_s
  return "repetition of a #{second_harmonic_interval}" unless contrapuntal_motion != :repetition

  "#{contrapuntal_motion} motion from a #{first_harmonic_interval} to a #{second_harmonic_interval}"
end

#upper_melodic_interval ⇒ Object (private) 



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# File 'lib/head_music/analysis/motion.rb', line 61

def upper_melodic_interval
  HeadMusic::Analysis::MelodicInterval.new(upper_notes.first, upper_notes.last)
end

#upper_notes ⇒ Object (private) 



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# File 'lib/head_music/analysis/motion.rb', line 69

def upper_notes
  [first_harmonic_interval, second_harmonic_interval].map(&:upper_note)
end