Class: Geospatial::Tiles

Inherits:
Object
  • Object
show all
Defined in:
lib/geospatial/tiles.rb

Constant Summary collapse

R2D =

Radians to degrees multiplier

(180.0 / Math::PI)
D2R = 
(Math::PI / 180.0)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(box, zoom = 5) ⇒ Tiles

Returns a new instance of Tiles.



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# File 'lib/geospatial/tiles.rb', line 29

def initialize(box, zoom = 5)
	@box = box
	@zoom = zoom
end

Instance Attribute Details

#box ⇒ Object (readonly)

Returns the value of attribute box.



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# File 'lib/geospatial/tiles.rb', line 34

def box
  @box
end

#zoom ⇒ Object (readonly)

Returns the value of attribute zoom.



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# File 'lib/geospatial/tiles.rb', line 35

def zoom
  @zoom
end

Instance Method Details

#each(zoom = @zoom) ⇒ Object 



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# File 'lib/geospatial/tiles.rb', line 54

def each(zoom = @zoom)
	return to_enum(:each, zoom) unless block_given?
	
	min = map(*@box.min, zoom)
	max = map(*@box.max, zoom)
	
	(min[0].floor...max[0].ceil).each do |x|
		# The y axis is reversed... (i.e. the origin is in the top left)
		(max[1].floor...min[1].ceil).each do |y|
			yield zoom, x, y
		end
	end
end

#map(longitude, latitude, zoom = @zoom) ⇒ Object 



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# File 'lib/geospatial/tiles.rb', line 37

def map(longitude, latitude, zoom = @zoom)
	n = 2 ** zoom
	
	x = n * ((longitude + 180.0) / 360.0)
	y = n * (1.0 - (Math::log(Math::tan(latitude * D2R) + (1.0 / Math::cos(latitude * D2R))) / Math::PI)) / 2.0
	
	return x, y
end

#unmap(x, y, zoom = @zoom) ⇒ Object 



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# File 'lib/geospatial/tiles.rb', line 46

def unmap(x, y, zoom = @zoom)
	n = 2 ** zoom
	longitude = x / n * 360.0 - 180.0
	latitude = Math::arctan(Math::sinh(Math::PI * (1.0 - 2.0 * y / n))) * R2D
	
	return longitude, latitude
end