openwebrx-clone/htdocs/nite-overlay.js

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2019-07-06 22:52:11 +00:00
/* Nite v1.7
* A tiny library to create a night overlay over the map
* Author: Rossen Georgiev @ https://github.com/rossengeorgiev
* Requires: GMaps API 3
*/
var nite = {
map: null,
date: null,
sun_position: null,
earth_radius_meters: 6371008,
marker_twilight_civil: null,
marker_twilight_nautical: null,
marker_twilight_astronomical: null,
marker_night: null,
init: function(map) {
if(typeof google === 'undefined'
|| typeof google.maps === 'undefined') throw "Nite Overlay: no google.maps detected";
this.map = map;
this.sun_position = this.calculatePositionOfSun();
this.marker_twilight_civil = new google.maps.Circle({
map: this.map,
center: this.getShadowPosition(),
radius: this.getShadowRadiusFromAngle(0.566666),
fillColor: "#000",
fillOpacity: 0.1,
strokeOpacity: 0,
clickable: false,
editable: false
});
this.marker_twilight_nautical = new google.maps.Circle({
map: this.map,
center: this.getShadowPosition(),
radius: this.getShadowRadiusFromAngle(6),
fillColor: "#000",
fillOpacity: 0.1,
strokeOpacity: 0,
clickable: false,
editable: false
});
this.marker_twilight_astronomical = new google.maps.Circle({
map: this.map,
center: this.getShadowPosition(),
radius: this.getShadowRadiusFromAngle(12),
fillColor: "#000",
fillOpacity: 0.1,
strokeOpacity: 0,
clickable: false,
editable: false
});
this.marker_night = new google.maps.Circle({
map: this.map,
center: this.getShadowPosition(),
radius: this.getShadowRadiusFromAngle(18),
fillColor: "#000",
fillOpacity: 0.1,
strokeOpacity: 0,
clickable: false,
editable: false
});
},
getShadowRadiusFromAngle: function(angle) {
var shadow_radius = this.earth_radius_meters * Math.PI * 0.5;
var twilight_dist = ((this.earth_radius_meters * 2 * Math.PI) / 360) * angle;
return shadow_radius - twilight_dist;
},
getSunPosition: function() {
return this.sun_position;
},
getShadowPosition: function() {
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.sun_position = this.calculatePositionOfSun(this.date);
var shadow_position = this.getShadowPosition();
this.marker_twilight_civil.setCenter(shadow_position);
this.marker_twilight_nautical.setCenter(shadow_position);
this.marker_twilight_astronomical.setCenter(shadow_position);
this.marker_night.setCenter(shadow_position);
},
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 ms_past_midnight = ((date.getUTCHours() * 60 + date.getUTCMinutes()) * 60 + date.getUTCSeconds()) * 1000 + date.getUTCMilliseconds();
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);
var y = Math.tan(rad*(obliq_corr/2))*Math.tan(rad*(obliq_corr/2));
var rq_of_time = 4*((y*Math.sin(2*rad*mean_long_sun)-2*eccent*Math.sin(rad*mean_anom_sun)+4*eccent*y*Math.sin(rad*mean_anom_sun)*Math.cos(2*rad*mean_long_sun)-0.5*y*y*Math.sin(4*rad*mean_long_sun)-1.25*eccent*eccent*Math.sin(2*rad*mean_anom_sun))/rad);
var true_solar_time_in_deg = ((ms_past_midnight+rq_of_time*60000) % 86400000) / 240000;
var lng = -((true_solar_time_in_deg < 0) ? true_solar_time_in_deg + 180 : true_solar_time_in_deg - 180);
return new google.maps.LatLng(lat, lng);
},
setDate: function(date) {
this.date = date;
this.refresh();
},
setMap: function(map) {
this.map = map;
this.marker_twilight_civil.setMap(this.map);
this.marker_twilight_nautical.setMap(this.map);
this.marker_twilight_astronomical.setMap(this.map);
this.marker_night.setMap(this.map);
},
show: function() {
this.marker_twilight_civil.setVisible(true);
this.marker_twilight_nautical.setVisible(true);
this.marker_twilight_astronomical.setVisible(true);
this.marker_night.setVisible(true);
this.refresh();
},
hide: function() {
this.marker_twilight_civil.setVisible(false);
this.marker_twilight_nautical.setVisible(false);
this.marker_twilight_astronomical.setVisible(false);
this.marker_night.setVisible(false);
},
isVisible: function() {
return this.marker_night.getVisible();
}
}