updated nite overlay library to v1.2

Author: rossengeorgiev

js/nite-overlay.js

@@ -1,4 +1,4 @@
-/* Nite v1.0
+/* Nite v1.2
  * A tiny library to create a night overlay over the map
  * Author: Rossen Georgiev @ https://github.com/rossengeorgiev
  * Requires: GMaps API 3
@@ -14,13 +14,13 @@ var nite = {
     shadow_radius: parseInt(6371 * Math.PI * 500),
     sun_position: null,
 
-    init: function(map) {  
+    init: function(map) {
         if(typeof google === 'undefined'
            || typeof google.maps === 'undefined') throw "Nite Overlay: no google.maps detected";
-        
+
         this.map = map;
-        this.refreshSunZenith();
-        
+        this.sun_position = this.calculatePositionOfSun();
+
         this.marker_shadow = new google.maps.Circle({
             map: this.map,
             center: this.getShadowPosition(),
@@ -29,8 +29,8 @@ var nite = {
             fillOpacity: 0.1,
             strokeOpacity: 0,
             clickable: false,
-            editable: false 
-        }); 
+            editable: false
+        });
 
         this.marker_shadow_lite = new google.maps.Circle({
             map: this.map,
@@ -40,36 +40,40 @@ var nite = {
             fillOpacity: 0.1,
             strokeOpacity: 0,
             clickable: false,
-            editable: false 
-        }); 
+            editable: false
+        });
+    },
+    getSunPosition: function() {
+        return this.sun_position;
     },
     getShadowPosition: function() {
-        return new google.maps.LatLng(-this.sun_position.lat(), -this.sun_position.lng() + 180);
+        return (this.sun_position) ? new google.maps.LatLng(-this.sun_position.lat(), -this.sun_position.lng() + 180) : null;
     },
     refresh: function() {
         if(!this.isVisible()) return;
-        this.refreshSunZenith();
+        this.sun_position = this.calculatePositionOfSun(this.date);
         this.marker_shadow.setCenter(this.getShadowPosition());
         this.marker_shadow_lite.setCenter(this.getShadowPosition());
     },
-    refreshSunZenith: function() {
+    jday: function(date) {
+        return (date.getTime() / 86400000.0) + 2440587.5;
+    },
+    calculatePositionOfSun: function(date) {
+        date = (date instanceof Date) ? date : new Date();
+
         var rad = 0.017453292519943295;
 
         // based on NOAA solar calculations
-        var utc = new Date();
-        if(this.date) { utc = new Date(this.date); }
-        utc = new Date(utc.getTime() + utc.getTimezoneOffset() * 60000);
-        var mins_past_midnight = (utc.getHours() * 60 + utc.getMinutes()) / 1440;
-        var jd = 2415018.5 - ((new Date("01/01/1900 00:00:00 UTC")).getTime() - utc.getTime()) / 1000 / 60 / 60 / 24;
-        var jc = (jd - 2451545)/36525;
+        var mins_past_midnight = (date.getUTCHours() * 60 + date.getUTCMinutes()) / 1440;
+        var jc = (this.jday(date) - 2451545)/36525;
         var mean_long_sun = (280.46646+jc*(36000.76983+jc*0.0003032)) % 360;
         var mean_anom_sun = 357.52911+jc*(35999.05029-0.0001537*jc);
         var sun_eq = Math.sin(rad*mean_anom_sun)*(1.914602-jc*(0.004817+0.000014*jc))+Math.sin(rad*2*mean_anom_sun)*(0.019993-0.000101*jc)+Math.sin(rad*3*mean_anom_sun)*0.000289;
         var sun_true_long = mean_long_sun + sun_eq;
         var sun_app_long = sun_true_long - 0.00569 - 0.00478*Math.sin(rad*125.04-1934.136*jc);
         var mean_obliq_ecliptic = 23+(26+((21.448-jc*(46.815+jc*(0.00059-jc*0.001813))))/60)/60;
         var obliq_corr = mean_obliq_ecliptic + 0.00256*Math.cos(rad*125.04-1934.136*jc);
-        
+
         var lat = Math.asin(Math.sin(rad*obliq_corr)*Math.sin(rad*sun_app_long)) / rad;
 
         var eccent = 0.016708634-jc*(0.000042037+0.0000001267*jc);
@@ -78,25 +82,25 @@ var nite = {
         var true_solar_time = (mins_past_midnight*1440+rq_of_time) % 1440;
         var lng = (true_solar_time/4 < 0) ? true_solar_time/4 + 180 : true_solar_time/4 - 180;
 
-        this.sun_position = new google.maps.LatLng(lat, lng);
+        return new google.maps.LatLng(lat, lng);
     },
     setDate: function(date) {
-        this.date = date;        
+        this.date = date;
         this.refresh();
     },
     setMap: function(map) {
-        this.map = map;        
+        this.map = map;
     },
     show: function() {
-        this.marker_shadow.setVisible(true); 
-        this.marker_shadow_lite.setVisible(true); 
+        this.marker_shadow.setVisible(true);
+        this.marker_shadow_lite.setVisible(true);
         this.refresh();
     },
     hide: function() {
-        this.marker_shadow.setVisible(false); 
-        this.marker_shadow_lite.setVisible(false); 
+        this.marker_shadow.setVisible(false);
+        this.marker_shadow_lite.setVisible(false);
     },
     isVisible: function() {
-        return this.marker_shadow.getVisible(); 
+        return this.marker_shadow.getVisible();
     }
 }