Class: HeadMusic::Style::Guidelines::DirectionChanges

Inherits:
HeadMusic::Style::Guideline show all
Defined in:
lib/head_music/style/guidelines/direction_changes.rb

Overview

A melodic line should change direction often enough. Configurable via the maximum_notes_per_direction: option; subclasses may set a MAXIMUM_NOTES_PER_DIRECTION default and their own MESSAGE.

Instance Method Summary collapse

Constructor Details

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

Instance Method Details

#marks ⇒ Object 



8
9
10
11
12
13
 
# File 'lib/head_music/style/guidelines/direction_changes.rb', line 8

def marks
  return unless overage.positive?

  penalty_exponent = overage**0.5
  HeadMusic::Style::Mark.for_all(notes, fitness: HeadMusic::PENALTY_FACTOR**penalty_exponent)
end

#maximum_notes_per_direction ⇒ Object (private) 



23
24
25
 
# File 'lib/head_music/style/guidelines/direction_changes.rb', line 23

def maximum_notes_per_direction
  options.fetch(:maximum_notes_per_direction) { self.class::MAXIMUM_NOTES_PER_DIRECTION }
end

#melodic_intervals_changing_direction ⇒ Object (private) 



31
32
33
34
35
 
# File 'lib/head_music/style/guidelines/direction_changes.rb', line 31

def melodic_intervals_changing_direction
  melodic_intervals.each_cons(2).reject do |interval_pair|
    interval_pair[0].direction == interval_pair[1].direction
  end
end

#notes_per_direction ⇒ Object (private) 



27
28
29
 
# File 'lib/head_music/style/guidelines/direction_changes.rb', line 27

def notes_per_direction
  notes.length.to_f / (melodic_intervals_changing_direction.length + 1)
end

#overage ⇒ Object (private) 



17
18
19
20
21
 
# File 'lib/head_music/style/guidelines/direction_changes.rb', line 17

def overage
  return 0 if notes.length < 2

  [notes_per_direction - maximum_notes_per_direction, 0].max
end