Class: GeoMonitor::LatLngPoint

Inherits:
Object
  • Object
show all
Defined in:
lib/geo_monitor/lat_lng_point.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(lat: 0, lng: 0) ⇒ LatLngPoint

Returns a new instance of LatLngPoint.



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# File 'lib/geo_monitor/lat_lng_point.rb', line 4

def initialize(lat: 0, lng: 0)
  @lat = lat.to_f
  @lng = lng.to_f
end

Instance Attribute Details

#lat ⇒ Object

Returns the value of attribute lat.



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# File 'lib/geo_monitor/lat_lng_point.rb', line 3

def lat
  @lat
end

#lng ⇒ Object

Returns the value of attribute lng.



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# File 'lib/geo_monitor/lat_lng_point.rb', line 3

def lng
  @lng
end

Class Method Details

.from_number(xtile, ytile, zoom) ⇒ Object

Get the lat/lng for a specific tile at a zoom level From wiki.openstreetmap.org/wiki/Slippy_map_tilenames#Pseudo-code



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# File 'lib/geo_monitor/lat_lng_point.rb', line 24

def self.from_number(xtile, ytile, zoom)
  n = 2.0**zoom
  lng = xtile / n * 360.0 - 180.0
  lat_rad = Math.atan(Math.sinh(Math::PI * (1 - 2 * ytile / n)))
  lat = 180.0 * (lat_rad / Math::PI)
  new(lat: lat, lng: lng)
end

Instance Method Details

#to_3857 ⇒ Object

This needs better documentation, but projecting from EPSG:4326 to EPSG:3857



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# File 'lib/geo_monitor/lat_lng_point.rb', line 12

def to_3857
  d = Math::PI / 180
  max = 1 - 1E-15
  sin = [[Math.sin(lat * d), max].min, -max].max
  self.class.new(
    lng: ::GeoMonitor::Constants::R * lng * d,
    lat: ::GeoMonitor::Constants::R * Math.log((1 + sin) / (1 - sin)) / 2
  )
end