Class: HeadMusic::Rudiment::Pitch::StepDistance

Inherits:
Object
  • Object
show all
Defined in:
lib/head_music/rudiment/pitch/step_distance.rb

Overview

The number of diatonic steps from one pitch to another, signed: the letter steps between them, plus seven for each octave crossed.

The letter steps already carry one wrap of the scale, so a register difference counts one octave short whenever the starting letter sits above the ending letter – C4 to A4 is five steps, not twelve.

Constant Summary collapse

STEPS_PER_OCTAVE = 
7

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(from_pitch, to_pitch) ⇒ StepDistance

Returns a new instance of StepDistance.



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# File 'lib/head_music/rudiment/pitch/step_distance.rb', line 13

def initialize(from_pitch, to_pitch)
  @from_pitch = from_pitch
  @to_pitch = HeadMusic::Rudiment::Pitch.get(to_pitch)
end

Instance Attribute Details

#from_pitch ⇒ Object (readonly)

Returns the value of attribute from_pitch.



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# File 'lib/head_music/rudiment/pitch/step_distance.rb', line 11

def from_pitch
  @from_pitch
end

#to_pitch ⇒ Object (readonly)

Returns the value of attribute to_pitch.



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# File 'lib/head_music/rudiment/pitch/step_distance.rb', line 11

def to_pitch
  @to_pitch
end

Instance Method Details

#octave_adjustment ⇒ Object (private) 



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# File 'lib/head_music/rudiment/pitch/step_distance.rb', line 28

def octave_adjustment
  pitch_class_above? ? 1 : 0
end

#octave_changes ⇒ Object (private) 



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# File 'lib/head_music/rudiment/pitch/step_distance.rb', line 24

def octave_changes
  to_pitch.register - from_pitch.register - octave_adjustment
end

#pitch_class_above? ⇒ Boolean (private)

Returns:

  • (Boolean) 


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# File 'lib/head_music/rudiment/pitch/step_distance.rb', line 32

def pitch_class_above?
  from_pitch.natural_pitch_class_number > to_pitch.natural_pitch_class_number
end

#steps ⇒ Object 



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# File 'lib/head_music/rudiment/pitch/step_distance.rb', line 18

def steps
  from_pitch.letter_name_steps_to(to_pitch) + STEPS_PER_OCTAVE * octave_changes
end