Set the map units to something OpenLayers? actually understands...

[rails.git] / lib / osm.rb

diff --git a/lib/osm.rb b/lib/osm.rb
index 1941d6dafc41b9532ffd23e6455428bc2d316494..ae8e70896a7d3c7a775a05cc7b637527b9ca17b9 100644 (file)
--- a/lib/osm.rb
+++ b/lib/osm.rb
@@ -22,10 +22,11 @@ module OSM
       @clat = lat
       @clon = lon
       @degrees_per_pixel = degrees_per_pixel
+      @degrees_per_pixel = 0.0000000001 if @degrees_per_pixel < 0.0000000001
       @width = width
       @height = height
-      @dlon = width / 2 * degrees_per_pixel
-      @dlat = height / 2 * degrees_per_pixel  * cos(@clat * PI / 180)
+      @dlon = width / 2 * @degrees_per_pixel
+      @dlat = height / 2 * @degrees_per_pixel  * cos(@clat * PI / 180)
 
       @tx = xsheet(@clon - @dlon)
       @ty = ysheet(@clat - @dlat)
@@ -197,7 +198,7 @@ module OSM
     end
 
     def get_icon(min_lat, min_lon, max_lat, max_lon)
-      puts "getting icon for bbox #{min_lat},#{min_lon} - #{max_lat},#{max_lon}"
+      #puts "getting icon for bbox #{min_lat},#{min_lon} - #{max_lat},#{max_lon}"
       width = 50
       height = 50
       rat= Math.cos( ((max_lat + min_lat)/2.0) /  180.0 * 3.141592)
@@ -240,6 +241,34 @@ module OSM
 
   end
 
+  class GreatCircle
+    include Math
+
+    # initialise with a base position
+    def initialize(lat, lon)
+      @lat = lat * PI / 180
+      @lon = lon * PI / 180
+    end
+
+    # get the distance from the base position to a given position
+    def distance(lat, lon)
+      lat = lat * PI / 180
+      lon = lon * PI / 180
+      return 6372.795 * 2 * asin(sqrt(sin((lat - @lat) / 2) ** 2 + cos(@lat) * cos(lat) * sin((lon - @lon)/2) ** 2))
+    end
+
+    # get the worst case bounds for a given radius from the base position
+    def bounds(radius)
+      latradius = 2 * asin(sqrt(sin(radius / 6372.795 / 2) ** 2))
+      lonradius = 2 * asin(sqrt(sin(radius / 6372.795 / 2) ** 2 / cos(@lat) ** 2))
+      minlat = (@lat - latradius) * 180 / PI
+      maxlat = (@lat + latradius) * 180 / PI
+      minlon = (@lon - lonradius) * 180 / PI
+      maxlon = (@lon + lonradius) * 180 / PI
+      return { :minlat => minlat, :maxlat => maxlat, :minlon => minlon, :maxlon => maxlon }
+    end
+  end
+
   class GeoRSS
     def initialize(feed_title='OpenStreetMap GPS Traces', feed_description='OpenStreetMap GPS Traces', feed_url='http://www.openstreetmap.org/traces/')
       @doc = XML::Document.new