Class: EightCorner::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/eight_corner/base.rb

Overview

This class is a catch-all. Will be cleaned up, you know, sometime.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(x_extent, y_extent, options = {}) ⇒ Base

Returns a new instance of Base.



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# File 'lib/eight_corner/base.rb', line 12

def initialize(x_extent, y_extent, options={})
  defaults = {
    logger: Logger.new('/dev/null')
  }
  self.class.validate_options!(options, defaults)

  options = defaults.merge(options)

  @bounds = Bounds.new(x_extent, y_extent)
  @point_count = 8

  @log = options[:logger]
  # @figure_interdepencence = options[:figure_interdepencence]
end

Class Method Details

.validate_options!(options, defaults) ⇒ Object 



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# File 'lib/eight_corner/base.rb', line 5

def self.validate_options!(options, defaults)
  unknown_options = options.keys - defaults.keys
  if unknown_options.size > 0
    raise ArgumentError, "Unrecognized options: #{unknown_options.inspect}"
  end
end

Instance Method Details

#aas(angle_a, angle_b, side_A) ⇒ Object

angle, angle, side A / sin(a) == B / sin(b) return length of side_B



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# File 'lib/eight_corner/base.rb', line 272

def aas(angle_a, angle_b, side_A)
  side_A / Math.sin(deg2rad(angle_a)) * Math.sin(deg2rad(angle_b))
end

#angle(current, percent) ⇒ Object

pick an angle for the next point steer away from the corners by avoiding angles which tend toward the corner we are currently closest to.

current Point x & y extents percent : how far along the arc should we go?

as a float 0..1
always counter-clockwise.

return: an angle from current point.



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# File 'lib/eight_corner/base.rb', line 194

def angle(current, percent)

  range = Quadrant.angle_range_for(@bounds.quadrant(current))
  interp = Interpolate::Points.new({
    0 => range.begin,
    1 => range.end
  })

  interp.at(percent).to_i % 360
end

#deg2rad(degrees) ⇒ Object 



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# File 'lib/eight_corner/base.rb', line 261

def deg2rad(degrees)
  degrees * Math::PI / 180
end

#distance_to_boundary(point, degrees) ⇒ Object

what is the distance from point to extent, along a line of degrees angle



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# File 'lib/eight_corner/base.rb', line 206

def distance_to_boundary(point, degrees)
  degrees %= 360

  case degrees
    when 0 then
      point.x

    when 1..89 then
      to_top = aas(90-degrees, 90, point.y)
      to_right = aas(degrees, 90, @bounds.x - point.x)
      [to_top, to_right].min

    when 90 then
      @bounds.x - point.x

    when 91..179 then
      to_right = aas(180-degrees, 90, @bounds.x - point.x)
      to_bottom = aas(90-180-degrees, 90, @bounds.y - point.y)
      [to_right, to_bottom].min

    when 180 then
      @bounds.y - point.y

    when 181..269 then
      to_bottom = aas(90-degrees-180, 90, @bounds.y - point.y)
      to_left = aas(degrees - 180, 90, point.x)
      [to_bottom, to_left].min

    when 270 then
      point.x

    when 271..359 then
      to_left = aas(360-degrees, 90, point.x)
      to_top = aas(90-360-degrees, 90, point.y)
      [to_left, to_top].min

  end
end

#next_point(last_point, angle, distance) ⇒ Object 



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# File 'lib/eight_corner/base.rb', line 245

def next_point(last_point, angle, distance)
  # geometry black magic here. still not positive exactly why this works.
  # unit circle begins at 90 and goes counterclockwise.
  # we want to start at 0 and go clockwise
  # orientation of 0 degrees to coordinate space probably matters also.
  theta = (180 - angle) % 360

  point = Point.new
  point.x = (Math.sin(deg2rad(theta)) * distance + last_point.x).round
  point.y = (Math.cos(deg2rad(theta)) * distance + last_point.y).round
  point.distance_from_last = distance
  point.angle_from_last = angle
  point.bounds = @bounds
  point
end

#plot(str, options = {}) ⇒ Object 



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# File 'lib/eight_corner/base.rb', line 27

def plot(str, options={})
  defaults = {
    group_method: :group2,
    angle_method: :percentize_modulus_exp,
    distance_method: :percentize_modulus,
    start_method: :starting_point,
    # will the initial_potential, and potentials generated from previous
    # points in the same figure, be used to alter the angle to the next
    # point?
    point_interdependence: true,
    # 0.5 is 'no change' see angle_potential_interp
    initial_potential: 0.5
  }
  self.class.validate_options!(options, defaults)
  options = defaults.merge(options)

  mapper = StringMapper.new(group_count: @point_count-1)

  # 7 2-element arrays. each value is a float 0..1.
  # 1st: % applied to calculate an angle
  # 2nd: % applied to calculate a distance
  potentials = mapper.potentials(
    mapper.groups(str, options[:group_method]),
    options[:angle_method],
    options[:distance_method]
  )

  # the figure we are drawing.
  figure = Figure.new
  # set starting point.
  figure.points << send(options[:start_method], str)

  # a potential is a value derived from the previous point in a figure
  # these are used to modify the angle used to locate the next point in
  # the figure. in this way, previous figures add influence
  # which wouldn't be present if the figure were drawn on its own.
  #   - median potential (0.5) changes nothing.
  #   - extremely low potential (0.0) moves the angle 15% counter-clockwise
  #   - extremely high potential (1.0) moves the angle 15% clockwise
  angle_potential_interp = Interpolate::Points.new(0.0 => -0.15, 0.5 => 0.0, 1.0 => 0.15)

  # increase low distance potentials to encourage longer lines
  # this is added to the raw distance potential determined by the string mapper.
  #   - a distance_pct of 0 will have 0.3 added to it.
  #   - a distance_pct of 0.5 or greater will have nothing added to it.
  additional_distance_interp = Interpolate::Points.new(0.0 => 0.3, 0.5 => 0.0)

  previous_potential = options[:initial_potential]

  (@point_count - 1).times do |i|
    current_point = figure.points[i]

    # TODO encourage more open angles?
    angle_pct = potentials[i][0]
    distance_pct = potentials[i][1]

    @log.debug(['angle_pct', angle_pct])

    # if points can influence each other, apply potential from previous
    # point to the angle-selection process.
    if options[:point_interdependence]
      angle_pct_adjustment = angle_potential_interp.at(previous_potential)
      @log.debug(['angle_pct_adjustment', angle_pct_adjustment])

      @log.debug(['pre-ajustment', angle_pct, angle(current_point, angle_pct)])
      angle_pct += angle_pct_adjustment
      @log.debug(['post-ajustment', angle_pct, angle(current_point, angle_pct)])
    end

    angle_to_next = angle(current_point, angle_pct)
    dist_to_boundary = distance_to_boundary(current_point, angle_to_next)

    @log.debug(['angle_to_next', angle_to_next])
    @log.debug(['distance_to_boundary', dist_to_boundary])

    # if we're too close to the edge, go the opposite direction.
    # so we don't get trapped in a corner.
    if dist_to_boundary <= 1
      @log.debug('dist_to_boundary is close to border. adjust angle.')

      angle_to_next += 180
      angle_to_next %= 360
      dist_to_boundary = distance_to_boundary(current_point, angle_to_next)

      @log.debug(['after 180: angle_to_next', angle_to_next])
      @log.debug(['after 180: distance_to_boundary', dist_to_boundary])
    end

    # how to encourage more space-filling?
    # track how many points are in each quadrant.
    # if current point is in the most-populated one, move to least-populated.
    # if current point and previous point are too close together...
    # if current point and last point are in different quadrants...


    distance_pct += additional_distance_interp.at(distance_pct)

    # longer lines fill space better
    distance_pct = 0.3 if distance_pct < 0.3
    # keep away from bounds.
    distance_pct = 0.9 if distance_pct > 0.9

    distance = dist_to_boundary * distance_pct

    next_point = next_point(
      current_point,
      angle_to_next,
      distance
    )
    next_point.angle_pct = angle_pct
    next_point.distance_pct = distance_pct
    next_point.created_by_potential = previous_potential

    # TODO: how do we create invalid points?
    # some bug in distance_to_boundary, most likely.
    if ! next_point.valid?
      if next_point.x < 0
        next_point.x = 0
      end
      if next_point.y < 0
        next_point.y = 0
      end

      @log.error "point produced invalid next. '#{str}' #{i}"
      @log.error(['angle_to_next', angle_to_next])
      @log.error(['distance_to_boundary', dist_to_boundary])
      @log.error(['next_point', next_point])
    end

    figure.points << next_point
    previous_potential = figure.points.last.potential
  end

  figure
end

#rad2deg(radians) ⇒ Object 



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# File 'lib/eight_corner/base.rb', line 265

def rad2deg(radians)
  radians * 180 / Math::PI
end

#starting_point(str) ⇒ Object

return a starting point for string



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# File 'lib/eight_corner/base.rb', line 164

def starting_point(str)
  mapper = StringMapper.new
  raw_x_pct = mapper.percentize_modulus(str)
  raw_y_pct = mapper.percentize_modulus_exp(str)

  # mapper produces raw %'s 0..1.
  # figures that start out very close to a border often get trapped and
  # look strange, so we won't allow a starting point <30% or >70%.
  interp = Interpolate::Points.new(0 => 0.2, 1 => 0.8)

  x_pct = interp.at( raw_x_pct )
  y_pct = interp.at( raw_y_pct )

  Point.new(
    (x_pct * @bounds.x).to_i,
    (y_pct * @bounds.y).to_i
  )
end