Module: GeoCalc::Destination

Defined in:
lib/geo_calc/calc/destination.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.destination_point(base_point, brng, dist) ⇒ Array

Returns the destination point from this point having travelled the given distance (in km) on the given initial bearing (bearing may vary before destination is reached)

see(#williams.best.vwh.net/avform.htm#LL)

Parameters:

  • Initial (Numeric) —

    bearing in degrees

  • Distance (Numeric) —

    in km

Returns:

  • (Array) —

    Destination point



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# File 'lib/geo_calc/calc/destination.rb', line 16

def self.destination_point base_point, brng, dist
  dist = dist / base_point.earth_radius_km  # convert dist to angular distance in radians
  brng = brng.to_rad 
  lat1 = base_point.lat.to_rad
  lon1 = base_point.lon.to_rad

  lat2 = Math.asin( Math.sin(lat1) * Math.cos(dist) + Math.cos(lat1) * Math.sin(dist) * Math.cos(brng) )
  lon2 = lon1 + Math.atan2(Math.sin(brng) * Math.sin(dist) * Math.cos(lat1), Math.cos(dist) - Math.sin(lat1) * Math.sin(lat2))

  lon2 = (lon2 + 3*Math::PI) % (2*Math::PI) - Math::PI  # normalise to -180...+180   

  [lat2.to_deg, lon2.to_deg]
  # GeoPoint.new lat2.to_deg, lon2.to_deg      
end

Instance Method Details

#destination_point(brng, dist) ⇒ Object 



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# File 'lib/geo_calc/calc/destination.rb', line 3

def destination_point brng, dist
  GeoCalc::Destination.destination_point self, brng, dist
end