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routeguide: reimplement distance calculation

This commit is contained in:
Jan Tattermusch 2018-03-22 12:43:05 +01:00 committed by Eric Anderson
parent 19a64cc336
commit 92f95de3cb
1 changed files with 10 additions and 12 deletions
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22
examples/src/main/java/io/grpc/examples/routeguide/RouteGuideServer.java
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@ -268,25 +268,23 @@ public class RouteGuideServer {
/** /**
* Calculate the distance between two points using the "haversine" formula. * Calculate the distance between two points using the "haversine" formula.
* This code was taken from http://www.movable-type.co.uk/scripts/latlong.html. * The formula is based on http://mathforum.org/library/drmath/view/51879.html.
* *
* @param start The starting point * @param start The starting point
* @param end The end point * @param end The end point
* @return The distance between the points in meters * @return The distance between the points in meters
*/ */
private static int calcDistance(Point start, Point end) { private static int calcDistance(Point start, Point end) {
double lat1 = RouteGuideUtil.getLatitude(start); int r = 6371000; // earth radius in meters
double lat2 = RouteGuideUtil.getLatitude(end); double lat1 = toRadians(RouteGuideUtil.getLatitude(start));
double lon1 = RouteGuideUtil.getLongitude(start); double lat2 = toRadians(RouteGuideUtil.getLatitude(end));
double lon2 = RouteGuideUtil.getLongitude(end); double lon1 = toRadians(RouteGuideUtil.getLongitude(start));
int r = 6371000; // meters double lon2 = toRadians(RouteGuideUtil.getLongitude(end));
double phi1 = toRadians(lat1); double deltaLat = lat2 - lat1;
double phi2 = toRadians(lat2); double deltaLon = lon2 - lon1;
double deltaPhi = toRadians(lat2 - lat1);
double deltaLambda = toRadians(lon2 - lon1);
double a = sin(deltaPhi / 2) * sin(deltaPhi / 2) double a = sin(deltaLat / 2) * sin(deltaLat / 2)
+ cos(phi1) * cos(phi2) * sin(deltaLambda / 2) * sin(deltaLambda / 2); + cos(lat1) * cos(lat2) * sin(deltaLon / 2) * sin(deltaLon / 2);
double c = 2 * atan2(sqrt(a), sqrt(1 - a)); double c = 2 * atan2(sqrt(a), sqrt(1 - a));
return (int) (r * c); return (int) (r * c);