From 2acded222727efbde1e587631f3a97f9d95f7be5 Mon Sep 17 00:00:00 2001
From: zhaknafein <dabrigo@gmail.com>
Date: Tue, 5 Nov 2013 16:19:05 +0100
Subject: [PATCH] Added "endpoint" method
Added an "endpoint" method, to calculate a point given a starting point, distance and heading (in degrees)
---
lib/geocoder/calculations.rb | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/lib/geocoder/calculations.rb b/lib/geocoder/calculations.rb
index b543e662..eb43817f 100644
--- a/lib/geocoder/calculations.rb
+++ b/lib/geocoder/calculations.rb
@@ -254,6 +254,40 @@ module Geocoder
[center[0] + delta_lat, center[1] + delta_long]
end
+ ##
+ # Given a start point, distance, and heading (in degrees), provides
+ # an endpoint.
+ # The starting point is given in the same way that points are given to all
+ # Geocoder methods that accept points as arguments. It can be:
+ #
+ # * an array of coordinates ([lat,lon])
+ # * a geocodable address (string)
+ # * a geocoded object (one which implements a +to_coordinates+ method
+ # which returns a [lat,lon] array
+ #
+ def endpoint(start, heading, distance, units=nil)
+ units ||= Geocoder.config.units
+ radius = earth_radius(units)
+
+ start = extract_coordinates(start)
+
+ # convert degrees to radians
+ start = to_radians(start)
+
+ lat = start[0]
+ lon = start[1]
+ heading = to_radians(heading)
+ distance = distance.to_f
+
+ end_lat = Math.asin(Math.sin(lat)*Math.cos(distance/radius) +
+ Math.cos(lat)*Math.sin(distance/radius)*Math.cos(heading))
+
+ end_lon = lon+Math.atan2(Math.sin(heading)*Math.sin(distance/radius)*Math.cos(lat),
+ Math.cos(distance/radius)-Math.sin(lat)*Math.sin(end_lat))
+
+ to_degrees [end_lat, end_lon]
+ end
+
##
# Convert degrees to radians.
# If an array (or multiple arguments) is passed,
--
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