--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gnv-artifacts/src/main/java/de/intevation/gnv/utils/DistanceCalculator.java	Fri Sep 28 12:13:56 2012 +0200
@@ -0,0 +1,106 @@
+package de.intevation.gnv.utils;
+
+import com.vividsolutions.jts.geom.Coordinate;
+import com.vividsolutions.jts.geom.Point;
+
+import java.util.List;
+
+/**
+ * A helper class to calculate distances between points and coordinates.
+ *
+ * @author <a href="mailto:tim.englich@intevation.de">Tim Englich</a>
+ *
+ */
+public class DistanceCalculator {
+
+    private final static double flattening = 1.0 / 298.257233563;
+
+    private final static double earthRadius = 6378137.0 / 1000.0 ;
+
+    /**
+     * Constructor
+     */
+    public DistanceCalculator() {
+    }
+
+
+    /**
+     * Calculates the distance between two points.
+     *
+     * @param p1 First point.
+     * @param p2 Second point.
+     * @return the distance.
+     */
+    public static double calculateDistance(Point p1, Point p2){
+        return calculateDistance(p1.getCoordinate(), p2.getCoordinate());
+    }
+
+
+    /**
+     * Calculates the distance between two coordinates.
+     *
+     * @param p1 First coordinate.
+     * @param p2 Second coordinate.
+     * @return the distance.
+     */
+    public static double calculateDistance(Coordinate p1, Coordinate p2){
+        double resultValue = 0.0;
+
+        double b1 = p1.y;
+        double b2 = p2.y;
+
+        double l1 = p1.x;
+        double l2 = p2.x;
+
+
+        double F = (b1 + b2) / 2.0;
+        double G = (b1 - b2) / 2.0;
+        double l = (l1 - l2) / 2.0;
+
+        F = (Math.PI / 180.0) * F;
+        G = (Math.PI / 180.0) * G;
+        l = (Math.PI / 180.0) * l;
+
+        double S = ((Math.sin(G) * Math.sin(G)) * ((Math.cos(l) * Math.cos(l))))+
+                   ((Math.cos(F) * Math.cos(F)) * ((Math.sin(l) * Math.sin(l))));
+
+        double C = ((Math.cos(G) * Math.cos(G)) * ((Math.cos(l) * Math.cos(l))))+
+                   ((Math.sin(F) * Math.sin(F)) * ((Math.sin(l) * Math.sin(l))));
+
+        double w = Math.atan(Math.sqrt((S/C)));
+
+        double D = 2.0 * w * earthRadius;
+
+        double R = Math.sqrt((S*C)) / w;
+
+        double H1 = (3.0 * R - 1.0 ) / (2.0 * C);
+        double H2 = (3.0 * R + 1.0 ) / (2.0 * S);
+
+        resultValue = D * (1 + (flattening * H1 * (Math.sin(F) * Math.sin(F)) *
+                                                  (Math.cos(G) * Math.cos(G))) -
+                           (flattening * H2 * (Math.cos(F) * Math.cos(F)) *
+                                              (Math.sin(G) * Math.sin(G))));
+
+        return resultValue;
+    }
+
+    /**
+     * Calculates the length of a path specified by coordinates in <i>path</i>.
+     *
+     * @param path A list of coordinates.
+     * @return the length of the given path.
+     */
+    public static final double calculateDistance(List<Coordinate> path) {
+        int N = path.size();
+        if (N < 2) {
+            return 0d;
+        }
+        double sum = 0d;
+        for (int i = 1; i < N; ++i) {
+            sum += calculateDistance(path.get(i-1), path.get(i));
+        }
+        return sum;
+    }
+
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :