solarcompass/src/main/java/com/agnibho/android/solarcompass/CompassLogic.java

   1 /**********************************************************************
   2  * Title: Solar Compass
   3  * Description: Android app for finding directions using the sun
   4  * Author: Agnibho Mondal
   5  * Website: http://code.agnibho.com/solarcompass
   6  **********************************************************************
   7  Copyright (c) 2016 Agnibho Mondal
   8  All rights reserved
   9  **********************************************************************
  10  This file is part of Solar Compass.
  11
  12  Solar Compass is free software: you can redistribute it and/or modify
  13  it under the terms of the GNU General Public License as published by
  14  the Free Software Foundation, either version 3 of the License, or
  15  (at your option) any later version.
  16
  17  Solar Compass is distributed in the hope that it will be useful,
  18  but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  GNU General Public License for more details.
  21
  22  You should have received a copy of the GNU General Public License
  23  along with Solar Compass.  If not, see <http://www.gnu.org/licenses/>.
  24  **********************************************************************/
  25
  26 package com.agnibho.android.solarcompass;
  27
  28 import java.util.Calendar;
  29 import java.util.TimeZone;
  30
  31 public class CompassLogic {
  32
  33     /*
  34     Find Compass Angle
  35     Unit - Degrees
  36     */
  37     public static double getAngle(){
  38         return Math.toDegrees(getAzimuthAngle());
  39     }
  40
  41     /*
  42     Declination Angle
  43     Unit - Degrees
  44     */
  45     private static double getDeclinationAngle(){
  46         int dayNum= Calendar.getInstance().get(Calendar.DAY_OF_YEAR);
  47         return 23.45*Math.sin(Math.toRadians(360.0/365.0*(284.0+dayNum)));
  48     }
  49
  50     /*
  51     Hour Angle
  52     Unit - Degrees
  53      */
  54     private static double getHourAngle(){
  55         Calendar cal=Calendar.getInstance();
  56         cal.setTimeZone(TimeZone.getTimeZone("UTC"));
  57         double utc=(double)cal.get(Calendar.HOUR_OF_DAY)+(double)cal.get(Calendar.MINUTE)/60;
  58         double timeDiff=LocationData.getInstance().getLongitude()/15;
  59         double hour=(utc+timeDiff)%24.0;
  60         return (12-hour)*15;
  61     }
  62
  63     /*
  64     Altitude Angle
  65     Unit - Radians
  66      */
  67     private static double getAltitudeAngle(){
  68         double latitude=Math.toRadians(LocationData.getInstance().getLatitude());
  69         double declination=Math.toRadians(getDeclinationAngle());
  70         double hourAngle=Math.toRadians(getHourAngle());
  71         double sinAlt=Math.cos(latitude)*Math.cos(declination)*Math.cos(hourAngle)+Math.sin(latitude)*Math.sin(declination);
  72         return Math.asin(sinAlt);
  73     }
  74
  75     /*
  76     Azimuth Angle
  77     Unit - Radians
  78      */
  79     private static double getAzimuthAngle(){
  80         double latitude=Math.toRadians(LocationData.getInstance().getLatitude());
  81         double declination=Math.toRadians(getDeclinationAngle());
  82         double altitude=getAltitudeAngle();
  83         double cosAz=(Math.sin(altitude)*Math.sin(latitude)-Math.sin(declination))/(Math.cos(altitude)*Math.cos(latitude));
  84         double azimuth=Math.acos(cosAz);
  85         if(getHourAngle()<0){
  86             if(azimuth>0){
  87                 azimuth=-azimuth;
  88             }
  89         }
  90         else{
  91             if(azimuth<0){
  92                 azimuth=-azimuth;
  93             }
  94         }
  95         return azimuth;
  96     }
  97 }