GeoMatchUtil.java

package com.browseengine.bobo.util;

public class GeoMatchUtil {
  public static final float EARTH_RADIUS_MILES = 3956.0f;
  public static final float EARTH_RADIUS_KM = 6371.0f;

  public static final float LATITUDE_DEGREES_MIN = -90.0f;
  public static final float LATITUDE_DEGREES_MAX = 90.0f;
  public static final float LONGITUDE_DEGREES_MIN = -180.0f;
  public static final float LONGITUDE_DEGREES_MAX = 180.0f;

  public static float degreesToRadians(float degrees) {
    return (float) (degrees * (Math.PI / 180));
  }

  public static float getMilesRadiusCosine(float radiusInMiles) {
    float radiusCosine = (float) (Math.cos(radiusInMiles / EARTH_RADIUS_MILES));
    return radiusCosine;
  }

  public static float getKMRadiusCosine(float radiusInKM) {
    float radiusCosine = (float) (Math.cos(radiusInKM / EARTH_RADIUS_KM));
    return radiusCosine;
  }

  public static float[] geoMatchCoordsFromDegrees(float latDegrees, float lonDegrees) {
    float[] geoMatchCoords;

    if (Float.isNaN(latDegrees) || Float.isNaN(lonDegrees)) {
      geoMatchCoords = new float[] { Float.NaN, Float.NaN, Float.NaN };
    } else {
      geoMatchCoords = geoMatchCoordsFromRadians((float) (latDegrees * (Math.PI / 180)),
        (float) (lonDegrees * (Math.PI / 180)));
    }
    return geoMatchCoords;
  }

  public static float[] geoMatchCoordsFromRadians(float latRadians, float lonRadians) {
    float[] geoMatchCoords;

    if (Float.isNaN(latRadians) || Float.isNaN(lonRadians)) {
      geoMatchCoords = new float[] { Float.NaN, Float.NaN, Float.NaN };
    } else {
      geoMatchCoords = new float[] { geoMatchXCoordFromRadians(latRadians, lonRadians),
          geoMatchYCoordFromRadians(latRadians, lonRadians), geoMatchZCoordFromRadians(latRadians) };
    }

    return geoMatchCoords;
  }

  public static float geoMatchXCoordFromDegrees(float latDegrees, float lonDegrees) {
    if (Float.isNaN(latDegrees) || Float.isNaN(lonDegrees)) {
      return Float.NaN;
    }

    return geoMatchXCoordFromRadians((float) (latDegrees * (Math.PI / 180)),
      (float) (lonDegrees * (Math.PI / 180)));
  }

  public static float geoMatchYCoordFromDegrees(float latDegrees, float lonDegrees) {
    if (Float.isNaN(latDegrees) || Float.isNaN(lonDegrees)) {
      return Float.NaN;
    }

    return geoMatchYCoordFromRadians((float) (latDegrees * (Math.PI / 180)),
      (float) (lonDegrees * (Math.PI / 180)));
  }

  public static float geoMatchZCoordFromDegrees(float latDegrees) {
    if (Float.isNaN(latDegrees)) {
      return Float.NaN;
    }

    return geoMatchZCoordFromRadians((float) (latDegrees * (Math.PI / 180)));
  }

  public static float geoMatchXCoordFromRadians(float latRadians, float lonRadians) {
    if (Float.isNaN(latRadians) || Float.isNaN(lonRadians)) {
      return Float.NaN;
    }

    return (float) (Math.cos(latRadians) * Math.cos(lonRadians));
  }

  public static float geoMatchYCoordFromRadians(float latRadians, float lonRadians) {
    if (Float.isNaN(latRadians) || Float.isNaN(lonRadians)) {
      return Float.NaN;
    }

    return (float) (Math.cos(latRadians) * Math.sin(lonRadians));
  }

  public static float geoMatchZCoordFromRadians(float latRadians) {
    if (Float.isNaN(latRadians)) {
      return Float.NaN;
    }

    return (float) Math.sin(latRadians);
  }

  public static float getMatchLatDegreesFromXYZCoords(float x, float y, float z) {
    return (float) Math.toDegrees(Math.asin(z));
  }

  public static float getMatchLonDegreesFromXYZCoords(float x, float y, float z) {
    float lon = (float) Math.toDegrees(Math.asin(y / Math.cos(Math.asin(z))));

    if (x < 0 && y > 0) return 180.0f - lon;
    else if (y < 0 && x < 0) return -180.0f - lon;
    else return lon;
  }

}