Module: HeadMusic::Style::Guideline::HarmonicContext

Included in:
HeadMusic::Style::Guideline
Defined in:
lib/head_music/style/guideline/harmonic_context.rb

Overview

What sounds together: the intervals between this voice and the cantus firmus, and the motion from one to the next.

Instance Method Summary collapse

Instance Method Details

#downbeat_harmonic_intervals ⇒ Object (protected) 



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# File 'lib/head_music/style/guideline/harmonic_context.rb', line 15

def downbeat_harmonic_intervals
  @downbeat_harmonic_intervals ||=
    sounding_together(
      cantus_firmus.notes.map { |note| HeadMusic::Analysis::HarmonicInterval.new(note.voice, voice, note.position) }
    )
end

#harmonic_intervals ⇒ Object (protected) 



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# File 'lib/head_music/style/guideline/harmonic_context.rb', line 22

def harmonic_intervals
  @harmonic_intervals ||=
    sounding_together(
      positions.map { |position| HeadMusic::Analysis::HarmonicInterval.new(cantus_firmus, voice, position) }
    )
end

#motions ⇒ Object (protected) 



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# File 'lib/head_music/style/guideline/harmonic_context.rb', line 9

def motions
  downbeat_harmonic_intervals.each_cons(2).map do |harmonic_interval_pair|
    HeadMusic::Analysis::Motion.new(*harmonic_interval_pair)
  end
end

#positions ⇒ Object (protected)

Every moment any voice attacks, so an interval is measured wherever one could have been heard.



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# File 'lib/head_music/style/guideline/harmonic_context.rb', line 36

def positions
  @positions ||= voices.flat_map(&:notes).map(&:position).sort.uniq(&:to_s)
end

#sounding_together(intervals) ⇒ Object (protected)

Fewer than two notes means one voice is silent, so nothing sounds together.



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# File 'lib/head_music/style/guideline/harmonic_context.rb', line 30

def sounding_together(intervals)
  intervals.reject { |interval| interval.notes.length < 2 }
end