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.Vector;
020    import org.apache.commons.math3.geometry.Space;
021    
022    /** This interface represents an hyperplane of a space.
023    
024     * <p>The most prominent place where hyperplane appears in space
025     * partitioning is as cutters. Each partitioning node in a {@link
026     * BSPTree BSP tree} has a cut {@link SubHyperplane sub-hyperplane}
027     * which is either an hyperplane or a part of an hyperplane. In an
028     * n-dimensions euclidean space, an hyperplane is an (n-1)-dimensions
029     * hyperplane (for example a traditional plane in the 3D euclidean
030     * space). They can be more exotic objects in specific fields, for
031     * example a circle on the surface of the unit sphere.</p>
032    
033     * @param <S> Type of the space.
034    
035     * @version $Id: Hyperplane.java 1416643 2012-12-03 19:37:14Z tn $
036     * @since 3.0
037     */
038    public interface Hyperplane<S extends Space> {
039    
040        /** Copy the instance.
041         * <p>The instance created is completely independant of the original
042         * one. A deep copy is used, none of the underlying objects are
043         * shared (except for immutable objects).</p>
044         * @return a new hyperplane, copy of the instance
045         */
046        Hyperplane<S> copySelf();
047    
048        /** Get the offset (oriented distance) of a point.
049         * <p>The offset is 0 if the point is on the underlying hyperplane,
050         * it is positive if the point is on one particular side of the
051         * hyperplane, and it is negative if the point is on the other side,
052         * according to the hyperplane natural orientation.</p>
053         * @param point point to check
054         * @return offset of the point
055         */
056        double getOffset(Vector<S> point);
057    
058        /** Check if the instance has the same orientation as another hyperplane.
059         * <p>This method is expected to be called on parallel hyperplanes. The
060         * method should <em>not</em> re-check for parallelism, only for
061         * orientation, typically by testing something like the sign of the
062         * dot-products of normals.</p>
063         * @param other other hyperplane to check against the instance
064         * @return true if the instance and the other hyperplane have
065         * the same orientation
066         */
067        boolean sameOrientationAs(Hyperplane<S> other);
068    
069        /** Build a sub-hyperplane covering the whole hyperplane.
070         * @return a sub-hyperplane covering the whole hyperplane
071         */
072        SubHyperplane<S> wholeHyperplane();
073    
074        /** Build a region covering the whole space.
075         * @return a region containing the instance
076         */
077        Region<S> wholeSpace();
078    
079    }