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 */
017package org.apache.commons.geometry.core.internal;
018
019import org.apache.commons.geometry.core.Point;
020import org.apache.commons.geometry.core.Region;
021import org.apache.commons.geometry.core.RegionLocation;
022import org.apache.commons.geometry.core.partitioning.EmbeddingHyperplane;
023
024/** Utility methods for {@link org.apache.commons.geometry.core.partitioning.HyperplaneSubset}
025 * implementations.
026 */
027public final class HyperplaneSubsets {
028
029    /** Utility class; no instantiation. */
030    private HyperplaneSubsets() {
031    }
032
033    /** Classify a point against a region embedded in a hyperplane.
034     * @param <P> Point implementation class
035     * @param <S> Subspace point implementation class
036     * @param <H> Hyperplane implementation class
037     * @param <R> Region implementation class
038     * @param pt the point to classify
039     * @param hyperplane hyperplane containing the embedded region
040     * @param embeddedRegion embedded region to classify against
041     * @return the region location of the given point
042     */
043    public static <
044        P extends Point<P>,
045        S extends Point<S>,
046        H extends EmbeddingHyperplane<P, S>,
047        R extends Region<S>> RegionLocation classifyAgainstEmbeddedRegion(final P pt,
048                final H hyperplane, final R embeddedRegion) {
049
050        if (hyperplane.contains(pt)) {
051            final S subPoint = hyperplane.toSubspace(pt);
052
053            return embeddedRegion.classify(subPoint);
054        }
055
056        return RegionLocation.OUTSIDE;
057    }
058
059    /** Return the closest point to a given point in a region embedded in a hyperplane.
060     * @param <P> Point implementation class
061     * @param <S> Subspace point implementation class
062     * @param <H> Hyperplane implementation class
063     * @param <R> Region implementation class
064     * @param pt point to find the closest point to
065     * @param hyperplane hyperplane containing the embedded region
066     * @param embeddedRegion embedded region to find the closest point in
067     * @return the closest point to {@code pt} in the embedded region
068     */
069    public static <
070        P extends Point<P>,
071        S extends Point<S>,
072        H extends EmbeddingHyperplane<P, S>,
073        R extends Region<S>> P closestToEmbeddedRegion(final P pt,
074                final H hyperplane, final R embeddedRegion) {
075
076        final S subPt = hyperplane.toSubspace(pt);
077
078        if (embeddedRegion.contains(subPt)) {
079            return hyperplane.toSpace(subPt);
080        }
081
082        final S subProjected = embeddedRegion.project(subPt);
083        if (subProjected != null) {
084            return hyperplane.toSpace(subProjected);
085        }
086
087        return null;
088    }
089}