    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017    package org.apache.commons.math3.geometry.partitioning;
    018
    019    import org.apache.commons.math3.geometry.Space;
    020
    021    /** This interface represents the remaining parts of an hyperplane after
    022     * other parts have been chopped off.
    023
    024     * <p>sub-hyperplanes are obtained when parts of an {@link
    025     * Hyperplane hyperplane} are chopped off by other hyperplanes that
    026     * intersect it. The remaining part is a convex region. Such objects
    027     * appear in {@link BSPTree BSP trees} as the intersection of a cut
    028     * hyperplane with the convex region which it splits, the chopping
    029     * hyperplanes are the cut hyperplanes closer to the tree root.</p>
    030
    031     * @param <S> Type of the embedding space.
    032
    033     * @version $Id: SubHyperplane.java 1416643 2012-12-03 19:37:14Z tn $
    034     * @since 3.0
    035     */
    036    public interface SubHyperplane<S extends Space> {
    037
    038        /** Copy the instance.
    039         * <p>The instance created is completely independent of the original
    040         * one. A deep copy is used, none of the underlying objects are
    041         * shared (except for the nodes attributes and immutable
    042         * objects).</p>
    043         * @return a new sub-hyperplane, copy of the instance
    044         */
    045        SubHyperplane<S> copySelf();
    046
    047        /** Get the underlying hyperplane.
    048         * @return underlying hyperplane
    049         */
    050        Hyperplane<S> getHyperplane();
    051
    052        /** Check if the instance is empty.
    053         * @return true if the instance is empty
    054         */
    055        boolean isEmpty();
    056
    057        /** Get the size of the instance.
    058         * @return the size of the instance (this is a length in 1D, an area
    059         * in 2D, a volume in 3D ...)
    060         */
    061        double getSize();
    062
    063        /** Compute the relative position of the instance with respect
    064         * to an hyperplane.
    065         * @param hyperplane hyperplane to check instance against
    066         * @return one of {@link Side#PLUS}, {@link Side#MINUS}, {@link Side#BOTH},
    067         * {@link Side#HYPER}
    068         */
    069        Side side(Hyperplane<S> hyperplane);
    070
    071        /** Split the instance in two parts by an hyperplane.
    072         * @param hyperplane splitting hyperplane
    073         * @return an object containing both the part of the instance
    074         * on the plus side of the instance and the part of the
    075         * instance on the minus side of the instance
    076         */
    077        SplitSubHyperplane<S> split(Hyperplane<S> hyperplane);
    078
    079        /** Compute the union of the instance and another sub-hyperplane.
    080         * @param other other sub-hyperplane to union (<em>must</em> be in the
    081         * same hyperplane as the instance)
    082         * @return a new sub-hyperplane, union of the instance and other
    083         */
    084        SubHyperplane<S> reunite(SubHyperplane<S> other);
    085
    086        /** Class holding the results of the {@link #split split} method.
    087         * @param <U> Type of the embedding space.
    088         */
    089        public static class SplitSubHyperplane<U extends Space> {
    090
    091            /** Part of the sub-hyperplane on the plus side of the splitting hyperplane. */
    092            private final SubHyperplane<U> plus;
    093
    094            /** Part of the sub-hyperplane on the minus side of the splitting hyperplane. */
    095            private final SubHyperplane<U> minus;
    096
    097            /** Build a SplitSubHyperplane from its parts.
    098             * @param plus part of the sub-hyperplane on the plus side of the
    099             * splitting hyperplane
    100             * @param minus part of the sub-hyperplane on the minus side of the
    101             * splitting hyperplane
    102             */
    103            public SplitSubHyperplane(final SubHyperplane<U> plus,
    104                                      final SubHyperplane<U> minus) {
    105                this.plus  = plus;
    106                this.minus = minus;
    107            }
    108
    109            /** Get the part of the sub-hyperplane on the plus side of the splitting hyperplane.
    110             * @return part of the sub-hyperplane on the plus side of the splitting hyperplane
    111             */
    112            public SubHyperplane<U> getPlus() {
    113                return plus;
    114            }
    115
    116            /** Get the part of the sub-hyperplane on the minus side of the splitting hyperplane.
    117             * @return part of the sub-hyperplane on the minus side of the splitting hyperplane
    118             */
    119            public SubHyperplane<U> getMinus() {
    120                return minus;
    121            }
    122
    123        }
    124
    125    }