Class: HeadMusic::Style::Guidelines::PreferContraryMotion

Inherits:
Annotation
  • Object
show all
Defined in:
lib/head_music/style/guidelines/prefer_contrary_motion.rb

Overview

A counterpoint guideline

Constant Summary collapse

MESSAGE = 
"Prefer contrary motion. Move voices in different melodic directions."

Instance Method Summary collapse

Constructor Details

This class inherits a constructor from HeadMusic::Style::Annotation

Instance Method Details

#direct_motion_ratio ⇒ Object (private) 



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# File 'lib/head_music/style/guidelines/prefer_contrary_motion.rb', line 21

def direct_motion_ratio
  return 0 if motions.empty?

  direct_motions.count / motions.count.to_f
end

#direct_motions ⇒ Object (private) 



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# File 'lib/head_music/style/guidelines/prefer_contrary_motion.rb', line 17

def direct_motions
  motions.select(&:direct?)
end

#marks ⇒ Object 



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# File 'lib/head_music/style/guidelines/prefer_contrary_motion.rb', line 8

def marks
  return nil if notes.length < 2
  return nil if direct_motion_ratio <= 0.5

  direct_motions.map { |motion| HeadMusic::Style::Mark.for_all(motion.notes) }
end