Point in polygon (Gmap)

polygon_utilities.rb

# encoding : utf-8
class Numeric
  def to_rad
    self.to_f / 180.0 * Math::PI
  end

  def to_deg
    self.to_f * 180.0 / Math::PI
  end
end
module PolygonUtilities


  #This function returns an array like [{:x => 12, :y => 22}, {:x => 12, :y => 22}, {:x => 12, :y => 22}]
  def to_polygon(conv = :rad)
    point_tab = []
    if conv == :rad
      coordinates.split.map{|p| p.split(',')}.each do |e|
        point_tab << {:x => e[0].to_f.to_rad, :y => e[1].to_f.to_rad}
      end
    else
      coordinates.split.map{|p| p.split(',')}.each do |e|
        point_tab << {:x => e[0].to_f, :y => e[1].to_f}
      end
    end
    point_tab
  end

  #This function returns true or false whether a point in is in the polygon or not
  def point_in_polygon?(lat, lng)
    i = 0
    p1 = p2 = {}
    poly = to_polygon
    poly_size = poly.size
    p1 = poly[0]
    xinters = 0.00
    counter = 0
    p = {:x => lat.to_rad, :y => lng.to_rad}

    while i <= poly_size
      p2 = poly[i % poly_size]
      if p[:y] > min(p1[:y], p2[:y])
        if p[:y] <= max(p1[:y], p2[:y])
          if p[:x] <= max(p1[:x],p2[:x])
            if p1[:y] != p2[:y]
              xinters = (p[:y] - p1[:y]) * (p2[:x] - p1[:x]) / (p2[:y] - p1[:y]) + p1[:x]
              if p1[:x] == p2[:x] || p[:x] <= xinters
                counter += 1
              end
            end
          end
        end
      end
      p1 = p2
      i += 1
    end
    counter % 2 == 0 ? false : true
  end

  private

  def min(x, y)
    x < y ? x : y
  end

  def max(x, y)
    x < y ? y : x
  end

end