Skip to content

Instantly share code, notes, and snippets.

@itsSaad

itsSaad/point-in-polygon.rb

Forked from kidbrax/point-in-polygon.rb
Last active August 29, 2015 14:06
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save itsSaad/71445483bd50ee670c1b to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save itsSaad/71445483bd50ee670c1b to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. @kidbrax kidbrax created this gist Sep 22, 2011.
    34 changes: 34 additions & 0 deletions point-in-polygon.rb
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,34 @@
    def point_in_polygon?(polygonPoints)
    return false if self.latitude.blank? or self.longitude.blank?
    polygonPoints.each do |point|
    point[0] = point[0].to_f
    point[1] = point[1].to_f
    end

    contains_point = false
    i = -1
    j = polygonPoints.size - 1
    while (i += 1) < polygonPoints.size
    a_point_on_polygon = polygonPoints[i]
    trailing_point_on_polygon = polygonPoints[j]
    if point_is_between_the_ys_of_the_line_segment?(a_point_on_polygon, trailing_point_on_polygon)
    if ray_crosses_through_line_segment?(a_point_on_polygon, trailing_point_on_polygon)
    contains_point = !contains_point
    end
    end
    j = i
    end
    contains_point
    end

    private

    def point_is_between_the_ys_of_the_line_segment?(a_point_on_polygon, trailing_point_on_polygon)
    (a_point_on_polygon[0] <= self.latitude && self.latitude < trailing_point_on_polygon[0]) ||
    (trailing_point_on_polygon[0] <= self.latitude && self.latitude < a_point_on_polygon[0])
    end

    def ray_crosses_through_line_segment?(a_point_on_polygon, trailing_point_on_polygon)
    (self.longitude < (trailing_point_on_polygon[1] - a_point_on_polygon[1]) * (self.latitude - a_point_on_polygon[0]) /
    (trailing_point_on_polygon[0] - a_point_on_polygon[0]) + a_point_on_polygon[1])
    end