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