--- a/artifacts/src/main/java/org/dive4elements/river/artifacts/WaterLineArtifact.java	Fri Aug 17 14:29:05 2018 +0200
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/WaterLineArtifact.java	Fri Aug 17 15:31:02 2018 +0200
@@ -8,24 +8,33 @@
 
 package org.dive4elements.river.artifacts;
 
-import org.dive4elements.artifacts.CallContext;
+import java.io.Serializable;
 
-import org.dive4elements.river.artifacts.geom.Lines;
-import org.dive4elements.river.model.FastCrossSectionLine;
-
+import org.dive4elements.artifacts.CallContext;
+import org.dive4elements.river.artifacts.states.DefaultState.ComputeType;
 
 /**
  * Interface, Artifact can create WaterLines (Water against Cross-Profile).
  */
 public interface WaterLineArtifact {
 
-    /** Get points that define a line of a (water)facet against a cross-
-     * section. */
-    public Lines.LineData getWaterLines(
-        int                  facetIdx,
-        FastCrossSectionLine      csl,
-        double                      d,
-        double                      w,
-        CallContext           context);
-}
-// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
+    /**
+     * Get points that define a line of a (water)facet against a cross-
+     * section.
+     *
+     * @param stateId
+     * @param hash
+     *
+     * @param waterLineIndex
+     *            The object whith wich this artifact determines which of the waterlevels to return. Given to the facet when
+     *            constructed. Can be an integer in the simple case, or a more complex description.
+     */
+    // REMARK: we are giving type, hash and stateId so individual artifacts may call back on their compute method, which
+    // needs
+    // those to hash the result data.
+    // Currently, the old implementations don't do that but simply execute the whole computation each time they are
+    // called...
+    // TODO: instead we should compute outside and provide the computed data to this method.
+    double getWaterLevel(ComputeType type, String hash, String stateId, double currentKm, Serializable waterLineIndex, double nextKm, double prevKm,
+            CallContext context);
+}
\ No newline at end of file