--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/Utils.java	Thu Apr 25 12:06:39 2013 +0200
@@ -0,0 +1,61 @@
+package org.dive4elements.river.artifacts.math;
+
+
+public final class Utils {
+
+    public static final double EPSILON = 1e-3;
+
+    private Utils() {
+    }
+
+    public static final boolean epsilonEquals(double a, double b) {
+        return epsilonEquals(a, b, EPSILON);
+    }
+
+    public static final boolean epsilonEquals(double a, double b, double eps) {
+        return Math.abs(a - b) < eps;
+    }
+
+    public static int relativeCCW(
+        double x1, double y1,
+        double x2, double y2,
+        double px, double py
+    ) {
+        if ((epsilonEquals(x1, x2) && epsilonEquals(y1, y2))
+        || ((epsilonEquals(x1, px) && epsilonEquals(y1, py)))) {
+            return 0; // Coincident points.
+        }
+        // Translate to the origin.
+        x2 -= x1;
+        y2 -= y1;
+        px -= x1;
+        py -= y1;
+        double slope2 = y2 / x2;
+        double slopep = py / px;
+        if (epsilonEquals(slope2, slopep)
+        || (epsilonEquals(x2, 0.0) && epsilonEquals(px, 0.0))) {
+            return y2 > EPSILON // Colinear.
+                ? (py < -EPSILON ? -1 : py > y2 ? 1 : 0)
+                : (py > -EPSILON ? -1 : py < y2 ? 1 : 0);
+        }
+        if (x2 >= EPSILON && slope2 >= EPSILON) {
+            return px >= EPSILON // Quadrant 1.
+                ? (slope2 > slopep ? 1 : -1)
+                : (slope2 < slopep ? 1 : -1);
+        }
+
+        if (y2 > EPSILON) {
+            return px < -EPSILON // Quadrant 2.
+                ? (slope2 > slopep ? 1 : -1)
+                : (slope2 < slopep ? 1 : -1);
+        }
+        if (slope2 >= EPSILON) {
+            return px >= EPSILON // Quadrant 3.
+                ? (slope2 < slopep ? 1 : -1)
+                : (slope2 > slopep ? 1 : -1);
+        }
+        return px < -EPSILON // Quadrant 4.
+            ? (slope2 < slopep ? 1 : -1)
+            : (slope2 > slopep ? 1 : -1);
+    }
+}