Module: Navigate

Defined in:
lib/navigate.rb,
lib/navigate/position.rb

Defined Under Namespace

Classes: Position

Constant Summary collapse

EARTH_RADIUS = 
{ 'KM' => 6371.009, 'MI' => 3958.761, 'NM' => 3440.070, 'YD' => 6967420, 'FT' => 20902260 }

Class Method Summary collapse

Class Method Details

.bearing(position1, position2) ⇒ Object 



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# File 'lib/navigate.rb', line 12

def self.bearing(position1, position2)
  dLon = (position2.longitude - position1.longitude).to_radians

  y = Math::sin(dLon) * Math::cos(position2.latitude.to_radians)
  x = Math::cos(position1.latitude.to_radians) * Math::sin(position2.latitude.to_radians) -
      Math::sin(position1.latitude.to_radians) * Math::cos(position2.latitude.to_radians) * Math::cos(dLon)

  Math::atan2(y, x).to_bearing
end

.destination(position, options = {}) ⇒ Object 



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# File 'lib/navigate.rb', line 22

def self.destination(position, options = {})
  radius = EARTH_RADIUS[options[:radius_unit] || 'KM']
  distance = options[:distance] || 100.0
  brng = options[:bearing] || 90.0

  new_lat = Math::asin(
          Math::sin(position.latitude.to_radians) * Math::cos(distance / radius) +
          Math::cos(position.latitude.to_radians) * Math::sin(distance / radius) *
          Math::cos(brng)
        )

  new_lon = position.longitude.to_radians + Math::atan2(
                  Math::sin(brng) * Math::sin(distance / radius) * Math::cos(position.latitude.to_radians),
                  Math::cos(distance / radius) - Math::sin(position.latitude.to_radians) * Math::sin(new_lat)
                )

  new_lon = (new_lon + Math::PI) % (2 * Math::PI) - Math::PI

  Position.new new_lat.to_degrees, new_lon.to_degrees
end

.distance_between(position1, position2, radius_unit = 'KM') ⇒ Object 



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# File 'lib/navigate.rb', line 4

def self.distance_between(position1, position2, radius_unit = 'KM')
  Math::acos(
    Math::sin(position1.latitude.to_radians) * Math::sin(position2.latitude.to_radians) +
    Math::cos(position1.latitude.to_radians) * Math::cos(position2.latitude.to_radians) *
    Math::cos((position2.longitude - position1.longitude).to_radians)
  ) * EARTH_RADIUS[radius_unit]
end