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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.euclidean.threed;
    18
    19  import java.util.ArrayList;
    20  import java.util.List;
    21  import java.util.Objects;
    22  import java.util.stream.Collectors;
    23  import java.util.stream.Stream;
    24
    25  import org.apache.commons.geometry.euclidean.threed.line.LineConvexSubset3D;
    26  import org.apache.commons.geometry.euclidean.threed.line.LinecastPoint3D;
    27  import org.apache.commons.geometry.euclidean.threed.line.Linecastable3D;
    28
    29  /** Class that performs linecast operations against arbitrary {@link BoundarySource3D}
    30   * instances. This class performs a brute-force computation of the intersections of the
    31   * line or line convex subset against all boundaries. Some data structures may support more
    32   * efficient algorithms and should therefore prefer those instead.
    33   */
    34  final class BoundarySourceLinecaster3D implements Linecastable3D {
    35
    36      /** The boundary source instance providing boundaries for the linecast operation. */
    37      private final BoundarySource3D boundarySrc;
    38
    39      /** Construct a new instance for linecasting against the given boundary source.
    40       * @param boundarySrc boundary source to linecast against.
    41       */
    42      BoundarySourceLinecaster3D(final BoundarySource3D boundarySrc) {
    43          this.boundarySrc = boundarySrc;
    44      }
    45
    46      /** {@inheritDoc} */
    47      @Override
    48      public List<LinecastPoint3D> linecast(final LineConvexSubset3D subset) {
    49          try (Stream<LinecastPoint3D> stream = getIntersectionStream(subset)) {
    50
    51              final List<LinecastPoint3D> results = stream.collect(Collectors.toCollection(ArrayList::new));
    52              LinecastPoint3D.sortAndFilter(results);
    53
    54              return results;
    55          }
    56      }
    57
    58      /** {@inheritDoc} */
    59      @Override
    60      public LinecastPoint3D linecastFirst(final LineConvexSubset3D subset) {
    61          try (Stream<LinecastPoint3D> stream = getIntersectionStream(subset)) {
    62              return stream.min(LinecastPoint3D.ABSCISSA_ORDER)
    63                      .orElse(null);
    64          }
    65      }
    66
    67      /** Return a stream containing intersections between the boundary source and the
    68       * given line convex subset.
    69       * @param subset line subset to intersect
    70       * @return a stream containing linecast intersections
    71       */
    72      private Stream<LinecastPoint3D> getIntersectionStream(final LineConvexSubset3D subset) {
    73          return boundarySrc.boundaryStream()
    74                  .map(boundary -> computeIntersection(boundary, subset))
    75                  .filter(Objects::nonNull);
    76      }
    77
    78      /** Compute the intersection between a boundary plane subset and line subset. Null is
    79       * returned if no intersection is discovered.
    80       * @param planeSubset plane subset from the boundary source
    81       * @param lineSubset line subset to intersect with
    82       * @return the linecast intersection between the two arguments or null if there is no such
    83       *      intersection
    84       */
    85      private LinecastPoint3D computeIntersection(final PlaneConvexSubset planeSubset,
    86              final LineConvexSubset3D lineSubset) {
    87          final Vector3D intersectionPt = planeSubset.intersection(lineSubset);
    88
    89          if (intersectionPt != null) {
    90              final Vector3D normal = planeSubset.getPlane().getNormal();
    91
    92              return new LinecastPoint3D(intersectionPt, normal, lineSubset.getLine());
    93          }
    94
    95          return null; // no intersection
    96      }
    97  }