1 files changed, 72 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/geometry/spherical/twod/SubCircle.java b/src/main/java/org/apache/commons/math3/geometry/spherical/twod/SubCircle.java
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index 0000000..97164cc
--- /dev/null
+++ b/src/main/java/org/apache/commons/math3/geometry/spherical/twod/SubCircle.java
@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.math3.geometry.spherical.twod;
+
+import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;
+import org.apache.commons.math3.geometry.partitioning.AbstractSubHyperplane;
+import org.apache.commons.math3.geometry.partitioning.Hyperplane;
+import org.apache.commons.math3.geometry.partitioning.Region;
+import org.apache.commons.math3.geometry.spherical.oned.Arc;
+import org.apache.commons.math3.geometry.spherical.oned.ArcsSet;
+import org.apache.commons.math3.geometry.spherical.oned.Sphere1D;
+import org.apache.commons.math3.util.FastMath;
+
+/** This class represents a sub-hyperplane for {@link Circle}.
+ * @since 3.3
+ */
+public class SubCircle extends AbstractSubHyperplane<Sphere2D, Sphere1D> {
+
+    /** Simple constructor.
+     * @param hyperplane underlying hyperplane
+     * @param remainingRegion remaining region of the hyperplane
+     */
+    public SubCircle(final Hyperplane<Sphere2D> hyperplane,
+                     final Region<Sphere1D> remainingRegion) {
+        super(hyperplane, remainingRegion);
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    protected AbstractSubHyperplane<Sphere2D, Sphere1D> buildNew(final Hyperplane<Sphere2D> hyperplane,
+                                                                 final Region<Sphere1D> remainingRegion) {
+        return new SubCircle(hyperplane, remainingRegion);
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public SplitSubHyperplane<Sphere2D> split(final Hyperplane<Sphere2D> hyperplane) {
+
+        final Circle thisCircle   = (Circle) getHyperplane();
+        final Circle otherCircle  = (Circle) hyperplane;
+        final double angle = Vector3D.angle(thisCircle.getPole(), otherCircle.getPole());
+
+        if (angle < thisCircle.getTolerance() || angle > FastMath.PI - thisCircle.getTolerance()) {
+            // the two circles are aligned or opposite
+            return new SplitSubHyperplane<Sphere2D>(null, null);
+        } else {
+            // the two circles intersect each other
+            final Arc    arc          = thisCircle.getInsideArc(otherCircle);
+            final ArcsSet.Split split = ((ArcsSet) getRemainingRegion()).split(arc);
+            final ArcsSet plus        = split.getPlus();
+            final ArcsSet minus       = split.getMinus();
+            return new SplitSubHyperplane<Sphere2D>(plus  == null ? null : new SubCircle(thisCircle.copySelf(), plus),
+                                                    minus == null ? null : new SubCircle(thisCircle.copySelf(), minus));
+        }
+
+    }
+
+}