Class: Sangaku::Grid

Inherits:
Object
  • Object
show all
Defined in:
lib/sangaku/grid.rb

Instance Method Summary collapse

Constructor Details

#initialize(xs, ys) ⇒ Grid

Returns a new instance of Grid.



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# File 'lib/sangaku/grid.rb', line 5

def initialize(xs, ys)
  @xs, @ys = xs, ys
end

Instance Method Details

#get_stars(poly) ⇒ Object

Raises:



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# File 'lib/sangaku/grid.rb', line 9

def get_stars(poly)
  raise Errors::OpenPolygonError.new unless poly.closed?
  stars = []

  @xs.each do |x|
    ys = poly.select(x, nil).map { |line| line.get_y(x) }
    next if ys.length % 2 != 0
    stars += ys.sort.each_slice(2).map do |s|
      height = s.reduce(:-).abs
      y = 0.5 * s.reduce(:+)
      xs = poly.select(nil, y).map { |line| line.get_x(y) }
      xs.sort!
      s = xs.zip(xs.rotate).find { |a, b| x.between?(a, b) }
      # TODO: de-hack
      next unless s
      width = 2 * [(x-s[0]).abs, (x-s[1]).abs].min
      Star.new([x, y], [width, height])
    end
  end

  @ys.each do |y|
    xs = poly.select(nil, y).map { |line| line.get_x(y) }
    next if xs.length % 2 != 0
    stars += xs.sort.each_slice(2).map do |s|
      width = s.reduce(:-).abs
      x = 0.5 * s.reduce(:+)
      ys = poly.select(x, nil).map { |line| line.get_y(x) }
      ys.sort!
      s = ys.zip(ys.rotate).find { |a, b| y.between?(a, b) }
      # TODO: de-hack
      next unless s
      height = 2 * [(y-s[0]).abs, (y-s[1]).abs].min
      Star.new([x, y], [width, height])
    end
  end

  #TODO: de-hack
  stars.reject{|s| s.nil?}
end