class EightCorner::Base

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

Public Class Methods

new(x_extent, y_extent, options={}) click to toggle source
# 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
validate_options!(options, defaults) click to toggle source
# 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

Public Instance Methods

aas(angle_a, angle_b, side_A) click to toggle source

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

# 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) click to toggle source

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.

# 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) click to toggle source
# File lib/eight_corner/base.rb, line 261
def deg2rad(degrees)
  degrees * Math::PI / 180
end
distance_to_boundary(point, degrees) click to toggle source

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

# 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) click to toggle source
# 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={}) click to toggle source
# 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) click to toggle source
# File lib/eight_corner/base.rb, line 265
def rad2deg(radians)
  radians * 180 / Math::PI
end
starting_point(str) click to toggle source

return a starting point for string

# 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