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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.Collections;
    21  import java.util.List;
    22  import java.util.stream.Collectors;
    23
    24  import org.apache.commons.geometry.core.Transform;
    25  import org.apache.commons.geometry.euclidean.internal.EuclideanUtils;
    26
    27  /** Internal {@link ConvexPolygon3D} implementation class that uses a list of vertices
    28   * to represent the plane subset.
    29   */
    30  final class VertexListConvexPolygon3D extends AbstractConvexPolygon3D {
    31
    32      /** Vertex loop defining the convex polygon. */
    33      private final List<Vector3D> vertices;
    34
    35      /** Construct a new instance with the given plane and list of vertices. Callers are responsible
    36       * for ensuring that the given vertices form a convex subset lying in {@code plane}. The list of
    37       * vertices should not contain the duplicated first endpoint. No validation is performed.
    38       * @param plane plane containing convex polygon
    39       * @param vertices vertices defining the convex polygon
    40       * @throws IllegalArgumentException if fewer than 3 vertices are given
    41       */
    42      VertexListConvexPolygon3D(final Plane plane, final List<Vector3D> vertices) {
    43          super(plane);
    44
    45          // sanity check
    46          if (vertices.size() < EuclideanUtils.TRIANGLE_VERTEX_COUNT) {
    47              throw new IllegalArgumentException("Convex polygon requires at least " +
    48                      EuclideanUtils.TRIANGLE_VERTEX_COUNT + " points; found " + vertices.size());
    49          }
    50
    51          this.vertices = Collections.unmodifiableList(vertices);
    52      }
    53
    54      /** {@inheritDoc} */
    55      @Override
    56      public List<Vector3D> getVertices() {
    57          return vertices;
    58      }
    59
    60      /** {@inheritDoc} */
    61      @Override
    62      public List<Triangle3D> toTriangles() {
    63          return Planes.convexPolygonToTriangleFan(getPlane(), vertices);
    64      }
    65
    66      /** {@inheritDoc} */
    67      @Override
    68      public VertexListConvexPolygon3D transform(final Transform<Vector3D> transform) {
    69          final Plane tPlane = getPlane().transform(transform);
    70          final List<Vector3D> tVertices = vertices.stream()
    71                  .map(transform)
    72                  .collect(Collectors.toList());
    73
    74          return new VertexListConvexPolygon3D(tPlane, tVertices);
    75      }
    76
    77      /** {@inheritDoc} */
    78      @Override
    79      public VertexListConvexPolygon3D reverse() {
    80          final Plane rPlane = getPlane().reverse();
    81          final List<Vector3D> rVertices = new ArrayList<>(vertices);
    82          Collections.reverse(rVertices);
    83
    84          return new VertexListConvexPolygon3D(rPlane, rVertices);
    85      }
    86  }