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::DIATONIC_SCALE_AUX, 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::PENTATONIC_MAJ, 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

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Scales

cromatic_index, diatonic_aux_scale_from, diatonic_scale_from, scale, scale_from

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

Class Method Details

.high_note(from, short) ⇒ Object

Returns the higher note of an interval calculates from its first note and number and quality in short notation



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# File 'lib/music-utils/interval/interval.rb', line 73

def self.high_note(from, short)
  quality, number = parse_short(short)
  
  while number > 7
    number = number - 7
  end
  
  from_note, from_alter = Note.parse(from)

  to_note = Scales.diatonic_scale_from(from_note)[number - 1]
  intervals = Scales::QUALITIES[number].key(quality)
  intervals += alter_impact_in_semitones(from_alter, false)
  
  from_note_index = Scales.cromatic_index(from_note.to_sym)
  to_note_index = from_note_index + intervals

  while to_note_index > 11
    to_note_index = to_note_index - 12
  end

  Scales::CROMATIC_SCALE[to_note_index].select do |note|  
    raw_note, alter = Note.parse(note)
    raw_note == to_note
  end.first
end

.parse_short(sn) ⇒ Object

Short notation parser method



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# File 'lib/music-utils/interval/interval.rb', line 100

def self.parse_short(sn)
  short = sn.to_s

  quality = short[0..1]
  number = short[2..3].to_i
  
  if quality == Scales::DIMP or quality == Scales::AUGP
    # nothing to do
  else
    quality = short[0]
    number = short[1..2].to_i
  end
  [quality, number]
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 59

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
  count += Interval.alter_impact_in_semitones(@note1_alt, true)
  count += Interval.alter_impact_in_semitones(@note2_alt, false)
  
  count
end

#short ⇒ Object

Returns the class interval in the short notation



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# File 'lib/music-utils/interval/interval.rb', line 66

def short
  quality + number.to_s 
end