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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.Collections;
20  import java.util.List;
21  
22  import org.apache.commons.geometry.core.Transform;
23  import org.apache.commons.geometry.core.partitioning.Hyperplane;
24  import org.apache.commons.geometry.core.partitioning.HyperplaneConvexSubset;
25  import org.apache.commons.geometry.core.partitioning.Split;
26  import org.apache.commons.geometry.euclidean.twod.ConvexArea;
27  
28  /** Interface representing a finite or infinite convex subset of points in a plane in Euclidean 3D
29   * space.
30   */
31  public interface PlaneConvexSubset extends PlaneSubset, HyperplaneConvexSubset<Vector3D> {
32  
33      /** {@inheritDoc} */
34      @Override
35      PlaneConvexSubset reverse();
36  
37      /** {@inheritDoc} */
38      @Override
39      PlaneConvexSubset transform(Transform<Vector3D> transform);
40  
41      /** {@inheritDoc} */
42      @Override
43      Split<PlaneConvexSubset> split(Hyperplane<Vector3D> splitter);
44  
45      /** {@inheritDoc} */
46      @Override
47      PlaneConvexSubset.Embedded getEmbedded();
48  
49      /** Get the vertices for the convex subset in a counter-clockwise order as viewed looking down the plane
50       * normal. Each vertex in the returned list is unique. If the boundary of the subset is closed, the start
51       * vertex is <em>not</em> repeated at the end of the list.
52       *
53       * <p>It is important to note that, in general, the list of vertices returned by this method
54       * is not sufficient to completely characterize the subset. For example, a simple triangle
55       * has 3 vertices, but an infinite area constructed from two parallel lines and two lines that
56       * intersect between them will also have 3 vertices. It is also possible for non-empty subsets to
57       * contain no vertices at all. For example, a subset with no boundaries (representing the full
58       * plane), a subset with a single boundary (ie, a half-plane), or a subset with two parallel boundaries will
59       * not contain any vertices.</p>
60       * @return the list of vertices for the plane convex subset in a counter-clockwise order as viewed looking
61       *      down the plane normal
62       */
63      List<Vector3D> getVertices();
64  
65      /** {@inheritDoc}
66       *
67       * <p>This method simply returns a singleton list containing this object.</p>
68       */
69      @Override
70      default List<PlaneConvexSubset> toConvex() {
71          return Collections.singletonList(this);
72      }
73  
74      /** Interface used to represent plane convex subsets as embedded 2D subspace regions.
75       */
76      interface Embedded extends PlaneSubset.Embedded {
77  
78          /** {@inheritDoc} */
79          @Override
80          ConvexArea getSubspaceRegion();
81      }
82  }