Class: BorderPatrol::Polygon

Inherits:
Array
  • Object
show all
Defined in:
lib/border_patrol/polygon.rb

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Polygon

Returns a new instance of Polygon.

Raises:



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# File 'lib/border_patrol/polygon.rb', line 3

def initialize(* args)
  args.flatten!
  args.uniq!
  raise InsufficientPointsToActuallyFormAPolygonError unless args.size > 2
  super(args)
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/border_patrol/polygon.rb', line 10

def ==(other)
  # Do we have the right number of points?
  return false unless other.size == size

  # Are the points in the right order?
  first, second = self.first(2)
  index = other.index(first)
  return false unless index
  direction = (other[index-1] == second) ? -1 : 1
  # Check if the two polygons have the same edges and the same points
  # i.e. [point1, point2, point3] is the same as [point2, point3, point1] is the same as [point3, point2, point1]
  each do |i|
    return false unless i == other[index]
    index = index + direction
    index = 0 if index == size
  end
  true
end

#bounding_box ⇒ Object 



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# File 'lib/border_patrol/polygon.rb', line 62

def bounding_box
  max_x, min_x, max_y, min_y = -Float::MAX, Float::MAX, -Float::MAX, Float::MAX
  each do |point|
    max_y = point.y if point.y > max_y
    min_y = point.y if point.y < min_y
    max_x = point.x if point.x > max_x
    min_x = point.x if point.x < min_x
  end
  [Point.new(min_x, max_y), Point.new(max_x, min_y)]
end

#contains_point?(point) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/border_patrol/polygon.rb', line 34

def contains_point?(point)
  return false unless inside_bounding_box?(point)
  c = false
  i = -1
  j = self.size - 1
  while (i += 1) < self.size
    if ((self[i].y <= point.y && point.y < self[j].y) ||
      (self[j].y <= point.y && point.y < self[i].y))
      if (point.x < (self[j].x - self[i].x) * (point.y - self[i].y) /
        (self[j].y - self[i].y) + self[i].x)
        c = !c
      end
    end
    j = i
  end
  return c
end

#hash ⇒ Object

Quick and dirty hash function



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# File 'lib/border_patrol/polygon.rb', line 30

def hash
  inject(0) { |sum, point| sum += point.x + point.y }
end

#inside_bounding_box?(point) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/border_patrol/polygon.rb', line 52

def inside_bounding_box?(point)
  bb_point_1, bb_point_2 = bounding_box
  max_x = [bb_point_1.x, bb_point_2.x].max
  max_y = [bb_point_1.y, bb_point_2.y].max
  min_x = [bb_point_1.x, bb_point_2.x].min
  min_y = [bb_point_1.y, bb_point_2.y].min

  !(point.x < min_x || point.x > max_x || point.y < min_y || point.y > max_y)
end