--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/StaticWKmsArtifact.java	Tue Jul 10 13:26:13 2012 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/StaticWKmsArtifact.java	Tue Jul 10 15:31:56 2012 +0000
@@ -16,6 +16,7 @@
 import de.intevation.artifacts.Artifact;
 import de.intevation.artifacts.ArtifactFactory;
 import de.intevation.artifacts.CallMeta;
+import de.intevation.flys.artifacts.math.Distance;
 import de.intevation.flys.artifacts.math.Linear;
 
 import de.intevation.flys.artifacts.model.CrossSectionWaterLineFacet;
@@ -34,6 +35,7 @@
 
 import de.intevation.flys.model.FastCrossSectionLine;
 
+
 /**
  * Artifact to access additional "waterlevel"-type of data, like the height
  * of protective measures (dikes).
@@ -52,6 +54,11 @@
     public static final String STATIC_STATE_NAME =
         "state.additional_wkms.static";
 
+    /** Data Item name to know whether we are Heighmarks and reveive
+     * some data slightly different. */
+    public static final String DATA_HEIGHT_TYPE =
+        "height_marks";
+
     /** One and only state to be in. */
     protected transient State state = null;
 
@@ -110,6 +117,7 @@
                 String name;
                 if (parts[0].equals(HEIGHTMARKS_POINTS)) {
                     name = HEIGHTMARKS_POINTS;
+                    addStringData(DATA_HEIGHT_TYPE, "true");
                 }
                 else {
                     name = STATIC_WKMS;
@@ -266,6 +274,34 @@
 
 
     /**
+     * Get the W at a specific km, only if it is closer to km than to any of
+     * the other given km.
+     * Return Double.NaN otherwise
+     *
+     * @param wkms WKms in which to search for a spatially close W value.
+     * @param km the input km, which is compared to values from wkms.
+     * @param next the next available input km.
+     * @param prev the previous available input km.
+     *
+     * @return W in wkms that is closer to km than to next and prev, or Double.NaN.
+     */
+    public double getWAtCloseKm(WKms wkms, double km, double next, double prev) {
+        int size = wkms.size();
+        // TODO handle edge cases (with no next or prev).
+        for (int i = 0; i < size; i++) {
+            double wkmsKm = wkms.getKm(i);
+            double dist = Distance.distance(wkmsKm, km);
+            if ((prev != km && dist <= Distance.distance(wkmsKm, prev))
+                && dist <= Distance.distance(wkmsKm, next)) {
+                return wkms.getW(i);    
+            }
+        }
+
+        return Double.NaN;
+    }
+
+
+    /**
      * Returns W at Km of WKms, searching linearly.
      * Returns -1 if not found.
      * @param wkms the WKms object to search for given km.
@@ -273,10 +309,11 @@
      * @return W at given km if in WKms, -1 if not found.
      */
     public static double getWAtKm(WKms wkms, double km) {
-        // Uninformed search.
+        // Uninformed search, intolerant.
+        double TOLERANCE = 0.0d;
         int size = wkms.size();
         for (int i = 0; i < size; i++) {
-            if (wkms.getKm(i) == km) {
+            if (Distance.within(wkms.getKm(i), km, TOLERANCE)) {
                 return wkms.getW(i);
             }
         }
@@ -288,12 +325,19 @@
     /**
      * Get points of line describing the surface of water at cross section.
      *
+     * @param idx Index of facet and in wkms array.
+     * @param csl FastCrossSectionLine to compute water surface agains.
+     * @param next The km of the next crosssectionline.
+     * @param prev The km of the previous crosssectionline.
+     *
      * @return an array holding coordinates of points of surface of water (
      *         in the form {{x1, x2}, {y1, y2}} ).
      */
     @Override
-    public Lines.LineData getWaterLines(int idx, FastCrossSectionLine csl) {
-        logger.debug("getWaterLines(" + idx + ")");
+    public Lines.LineData getWaterLines(int idx, FastCrossSectionLine csl,
+        double next, double prev
+    ) {
+        logger.debug("getWaterLines(" + idx + ")/" + identifier());
 
         List<Point2D> points = csl.getPoints();
 
@@ -302,8 +346,18 @@
         double km = csl.getKm();
 
         // Find W at km.
-        double wAtKm = getWAtKm(wkms, km);
-        if (wAtKm == -1) {
+        double wAtKm;
+
+        // If heightmarks, only deliver if data snaps.
+        if (getDataAsString(DATA_HEIGHT_TYPE) != null &&
+            getDataAsString(DATA_HEIGHT_TYPE).equals("true")) {
+            wAtKm = getWAtCloseKm(wkms, km, next, prev);
+        }
+        else {
+            wAtKm = getWAtKm(wkms, km);
+        }
+
+        if (wAtKm == -1 || Double.isNaN(wAtKm)) {
             logger.warn("Waterlevel at km " + km + " unknown.");
             return new Lines.LineData(new double[][] {{}}, 0d, 0d);
         }