SubCircle.java

/*
 * 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
 *
 *      https://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.
 */

/*
 * This is not the original file distributed by the Apache Software Foundation
 * It has been modified by the Hipparchus project
 */
package org.hipparchus.geometry.spherical.twod;

import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.geometry.partitioning.AbstractSubHyperplane;
import org.hipparchus.geometry.partitioning.Region;
import org.hipparchus.geometry.spherical.oned.Arc;
import org.hipparchus.geometry.spherical.oned.ArcsSet;
import org.hipparchus.geometry.spherical.oned.LimitAngle;
import org.hipparchus.geometry.spherical.oned.S1Point;
import org.hipparchus.geometry.spherical.oned.Sphere1D;
import org.hipparchus.geometry.spherical.oned.SubLimitAngle;
import org.hipparchus.util.FastMath;

/** This class represents a sub-hyperplane for {@link Circle}.
 */
public class SubCircle
    extends AbstractSubHyperplane<Sphere2D, S2Point, Circle, SubCircle, Sphere1D, S1Point, LimitAngle, SubLimitAngle> {

    /** Simple constructor.
     * @param hyperplane underlying hyperplane
     * @param remainingRegion remaining region of the hyperplane
     */
    public SubCircle(final Circle hyperplane,
                     final Region<Sphere1D, S1Point, LimitAngle, SubLimitAngle> remainingRegion) {
        super(hyperplane, remainingRegion);
    }

    /** {@inheritDoc} */
    @Override
    protected SubCircle buildNew(final Circle hyperplane, final Region<Sphere1D, S1Point, LimitAngle, SubLimitAngle> remainingRegion) {
        return new SubCircle(hyperplane, remainingRegion);
    }

    /** {@inheritDoc} */
    @Override
    public S2Point getInteriorPoint() {
        return isEmpty() ? null : getHyperplane().toSpace(getRemainingRegion().getInteriorPoint());
    }

    /** {@inheritDoc} */
    @Override
    public SplitSubHyperplane<Sphere2D, S2Point, Circle, SubCircle> split(final Circle hyperplane) {

        final double angle = Vector3D.angle(getHyperplane().getPole(), hyperplane.getPole());

        if (angle < getHyperplane().getTolerance() || angle > FastMath.PI - getHyperplane().getTolerance()) {
            // the two circles are aligned or opposite
            return new SplitSubHyperplane<>(null, null);
        } else {
            // the two circles intersect each other
            final Arc    arc          = getHyperplane().getInsideArc(hyperplane);
            final ArcsSet.Split split = ((ArcsSet) getRemainingRegion()).split(arc);
            final ArcsSet plus        = split.getPlus();
            final ArcsSet minus       = split.getMinus();
            return new SplitSubHyperplane<>(plus  == null ? null : new SubCircle(getHyperplane().copySelf(), plus),
                                            minus == null ? null : new SubCircle(getHyperplane().copySelf(), minus));
        }

    }

}