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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.geometry.enclosing.euclidean.threed;
    18
    19  import java.util.ArrayList;
    20  import java.util.Arrays;
    21  import java.util.List;
    22
    23  import org.apache.commons.geometry.core.GeometryTestUtils;
    24  import org.apache.commons.geometry.core.precision.DoublePrecisionContext;
    25  import org.apache.commons.geometry.core.precision.EpsilonDoublePrecisionContext;
    26  import org.apache.commons.geometry.enclosing.EnclosingBall;
    27  import org.apache.commons.geometry.euclidean.threed.Vector3D;
    28  import org.apache.commons.rng.UniformRandomProvider;
    29  import org.apache.commons.rng.sampling.UnitSphereSampler;
    30  import org.apache.commons.rng.simple.RandomSource;
    31  import org.junit.Assert;
    32  import org.junit.Test;
    33
    34  public class WelzlEncloser3DTest {
    35
    36      private static final double TEST_EPS = 1e-10;
    37
    38      private static final DoublePrecisionContext TEST_PRECISION =
    39              new EpsilonDoublePrecisionContext(TEST_EPS);
    40
    41      private final WelzlEncloser3D encloser = new WelzlEncloser3D(TEST_PRECISION);
    42
    43      @Test
    44      public void testNoPoints() {
    45          // arrange
    46          final String msg = "Unable to generate enclosing ball: no points given";
    47
    48          // act/assert
    49          GeometryTestUtils.assertThrows(() -> {
    50              encloser.enclose(null);
    51          }, IllegalArgumentException.class, msg);
    52
    53          GeometryTestUtils.assertThrows(() -> {
    54              encloser.enclose(new ArrayList<Vector3D>());
    55          }, IllegalArgumentException.class, msg);
    56      }
    57
    58      @Test
    59      public void testReducingBall() {
    60          // arrange
    61          final List<Vector3D> list =
    62                  Arrays.asList(Vector3D.of(-7.140397329568118, -16.571661242582177, 11.714458961735405),
    63                                Vector3D.of(-7.137986707455888, -16.570767323375720, 11.708602108715928),
    64                                Vector3D.of(-7.139185068549035, -16.570891204702250, 11.715554057357394),
    65                                Vector3D.of(-7.142682716997507, -16.571609818234290, 11.710787934580328),
    66                                Vector3D.of(-7.139018392423351, -16.574405614157020, 11.710518716711425),
    67                                Vector3D.of(-7.140870659936730, -16.567993074240455, 11.710914678204503),
    68                                Vector3D.of(-7.136350173659562, -16.570498228820930, 11.713965225900928),
    69                                Vector3D.of(-7.141675762759172, -16.572852471407028, 11.714033471449508),
    70                                Vector3D.of(-7.140453077221105, -16.570212820780647, 11.708624578004980),
    71                                Vector3D.of(-7.140322188726825, -16.574152894557717, 11.710305611121410),
    72                                Vector3D.of(-7.141116131477088, -16.574061164624560, 11.712938509321699));
    73
    74          // act
    75          final EnclosingBall<Vector3D> ball = encloser.enclose(list);
    76
    77          // assert
    78          Assert.assertTrue(ball.getRadius() > 0);
    79      }
    80
    81      @Test
    82      public void testInfiniteLoop() {
    83          // arrange
    84          // this test used to generate an infinite loop
    85          final List<Vector3D> list =
    86                  Arrays.asList(Vector3D.of(-0.89227075512164380, -2.89317694645713900, 14.84572323743355500),
    87                                Vector3D.of(-0.92099498940693580, -2.31086108263908940, 12.92071026467688300),
    88                                Vector3D.of(-0.85227999411005200, -3.06314731441320730, 15.40163831651287000),
    89                                Vector3D.of(-1.77399413020785970, -3.65630391378114260, 14.13190097751873400),
    90                                Vector3D.of(0.33157833272465354, -2.22813591757792160, 14.21225234159008200),
    91                                Vector3D.of(-1.53065579165484400, -1.65692084770139570, 14.61483055714788500),
    92                                Vector3D.of(-1.08457093941217140, -1.96100325935602980, 13.09265170575555000),
    93                                Vector3D.of(0.30029469589708850, -3.05470831395667370, 14.56352400426342600),
    94                                Vector3D.of(-0.95007443938638460, -1.86810946486118360, 15.14491234340057000),
    95                                Vector3D.of(-1.89661503804130830, -2.17004080885185860, 14.81235128513927000),
    96                                Vector3D.of(-0.72193328761607530, -1.44513142833618270, 14.52355724218561800),
    97                                Vector3D.of(-0.26895980939606550, -3.69512371522084140, 14.72272846327652000),
    98                                Vector3D.of(-1.53501693431786170, -3.25055166611021900, 15.15509062584274800),
    99                                Vector3D.of(-0.71727553535519410, -3.62284279460799100, 13.26256700929380700),
    100                               Vector3D.of(-0.30220950676137365, -3.25410412500779070, 13.13682612771606000),
    101                               Vector3D.of(-0.04543996608267075, -1.93081853923797750, 14.79497997883171400),
    102                               Vector3D.of(-1.53348892951571640, -3.66688919703524900, 14.73095600812074200),
    103                               Vector3D.of(-0.98034899533935820, -3.34004481162763960, 13.03245014017556800));
    104
    105         // act
    106         final EnclosingBall<Vector3D> ball = encloser.enclose(list);
    107
    108         // assert
    109         Assert.assertTrue(ball.getRadius() > 0);
    110     }
    111
    112     @Test
    113     public void testLargeSamples() {
    114         // arrange
    115         final UniformRandomProvider random = RandomSource.create(RandomSource.WELL_1024_A,
    116                                                                  0x35ddecfc78131e1dL);
    117         final UnitSphereSampler sr = new UnitSphereSampler(3, random);
    118         for (int k = 0; k < 50; ++k) {
    119
    120             // define the reference sphere we want to compute
    121             final double d = 25 * random.nextDouble();
    122             final double refRadius = 10 * random.nextDouble();
    123             final Vector3D refCenter = Vector3D.linearCombination(d, Vector3D.of(sr.nextVector()));
    124             // set up a large sample inside the reference sphere
    125             final int nbPoints = random.nextInt(1000);
    126
    127             final List<Vector3D> points = new ArrayList<>();
    128             for (int i = 0; i < nbPoints; ++i) {
    129                 final double r = refRadius * random.nextDouble();
    130                 points.add(Vector3D.linearCombination(1.0, refCenter, r, Vector3D.of(sr.nextVector())));
    131             }
    132
    133             // act/assert
    134             // test we find a sphere at most as large as the one used for random drawings
    135             checkSphere(points, refRadius);
    136         }
    137     }
    138
    139     private void checkSphere(final List<Vector3D> points, final double refRadius) {
    140
    141         final EnclosingBall<Vector3D> sphere = checkSphere(points);
    142
    143         // compare computed sphere with bounding sphere
    144         Assert.assertTrue(sphere.getRadius() <= refRadius);
    145
    146         // check removing any point of the support Sphere fails to enclose the point
    147         for (int i = 0; i < sphere.getSupportSize(); ++i) {
    148             final List<Vector3D> reducedSupport = new ArrayList<>();
    149             int count = 0;
    150             for (final Vector3D s : sphere.getSupport()) {
    151                 if (count++ != i) {
    152                     reducedSupport.add(s);
    153                 }
    154             }
    155             final EnclosingBall<Vector3D> reducedSphere = new SphereGenerator(TEST_PRECISION)
    156                     .ballOnSupport(reducedSupport);
    157             boolean foundOutside = false;
    158             for (int j = 0; j < points.size() && !foundOutside; ++j) {
    159                 if (!reducedSphere.contains(points.get(j), TEST_PRECISION)) {
    160                     foundOutside = true;
    161                 }
    162             }
    163             Assert.assertTrue(foundOutside);
    164         }
    165     }
    166
    167     private EnclosingBall<Vector3D> checkSphere(final List<Vector3D> points) {
    168
    169         final EnclosingBall<Vector3D> sphere = encloser.enclose(points);
    170
    171         // all points are enclosed
    172         for (final Vector3D v : points) {
    173             Assert.assertTrue(sphere.contains(v, TEST_PRECISION));
    174         }
    175
    176         // all support points are on the boundary
    177         final Vector3D center = sphere.getCenter();
    178         final double radius = sphere.getRadius();
    179
    180         for (final Vector3D s : sphere.getSupport()) {
    181             Assert.assertTrue(TEST_PRECISION.eqZero(center.distance(s) - radius));
    182         }
    183
    184         return sphere;
    185     }
    186 }