Class: MusicUtils::Interval

Inherits:
Object
  • Object
show all
Includes:
Scales
Defined in:
lib/music-utils/interval/interval.rb

Overview

This class represents a music interval

Constant Summary

Constants included from Scales

Scales::AUG, Scales::AUGP, Scales::CROMATIC_SCALE, Scales::DFLAT, Scales::DIATONIC_SCALE, Scales::DIM, Scales::DIMP, Scales::DO, Scales::DOF, Scales::DOFF, Scales::DOS, Scales::DOSS, Scales::DSHARP, Scales::FA, Scales::FAF, Scales::FAFF, Scales::FAS, Scales::FASS, Scales::FLAT, Scales::LA, Scales::LAF, Scales::LAFF, Scales::LAS, Scales::LASS, Scales::MAJ, Scales::MAJ_SCALE, Scales::MELODIC_MIN_SCALE, Scales::MI, Scales::MIF, Scales::MIFF, Scales::MIN, Scales::MIS, Scales::MISS, Scales::NATURAL_MIN_SCALE, Scales::PERF, Scales::QUALITIES, Scales::RE, Scales::REF, Scales::REFF, Scales::RES, Scales::RESS, Scales::SHARP, Scales::SI, Scales::SIF, Scales::SIFF, Scales::SIS, Scales::SISS, Scales::SOL, Scales::SOLF, Scales::SOLFF, Scales::SOLS, Scales::SOLSS

Instance Method Summary collapse

Methods included from Scales

diatonic_scale_from, scale

Constructor Details

#initialize(note1, note2, step) ⇒ Interval

Returns a new instance of Interval.



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# File 'lib/music-utils/interval/interval.rb', line 10

def initialize(note1, note2, step)
  @note1, @note1_alt = MusicUtils::Note.parse(note1)
  @note2, @note2_alt = MusicUtils::Note.parse(note2)
  @step = step
end

Instance Method Details

#number ⇒ Object

It classifies the diatonic interval



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# File 'lib/music-utils/interval/interval.rb', line 17

def number
  # initialize counter and index of scale
  i = note1_index
  count = 1
  
  count, i = no_unison(count, i)
  
  # Counting notes
  until_find_note2(i) { count += 1 }
  
  count = count + (8 * @step) - 1 if @step > 0
  count
end

#quality ⇒ Object

Returns the quality of the interval



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# File 'lib/music-utils/interval/interval.rb', line 70

def quality
  s = ( @step > 0 and semitones - (12 * @step) ) || semitones
  n = ( @step > 0 and number - (7 * @step) ) || number
  QUALITIES[n][s]
end

#semitones ⇒ Object

Returns the number of semitones



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# File 'lib/music-utils/interval/interval.rb', line 32

def semitones
  return CROMATIC_SCALE.length if @note1 == @note2
  
  # initialize counter and index of scale
  i = note1_index 
  count = 0
  
  # counting semi-tones
  until_find_note2(i) do |ii|
    # from 'mi' to 'fa' and 'si' to 'do' there 1 semi-tone
    if DIATONIC_SCALE[ii] == Scales::FA or DIATONIC_SCALE[ii] == Scales::DO
      count += 1
    else
      count += 2
    end
  end
  
  count = count + (12 * @step) if @step > 0
  
  # counting notes alterations
  case @note1_alt
    when Scales::FLAT   ; count += 1
    when Scales::SHARP  ; count -= 1
    when Scales::DFLAT  ; count += 2
    when Scales::DSHARP ; count -= 2
  end

  case @note2_alt
    when Scales::FLAT   ; count -= 1
    when Scales::SHARP  ; count += 1
    when Scales::DFLAT  ; count -= 2
    when Scales::DSHARP ; count += 2
  end

  count
end

#short ⇒ Object

Returns the class interval in the short notation



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# File 'lib/music-utils/interval/interval.rb', line 77

def short
  quality + number.to_s 
end