1   /* Copyright 2013 Applied Defense Solutions, Inc.
2    * Licensed to CS Communication & Systèmes (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS 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.orekit.propagation.events.handlers;
18  
19  import org.hipparchus.ode.events.Action;
20  import org.orekit.propagation.SpacecraftState;
21  import org.orekit.propagation.events.EventDetector;
22  
23  
24  /** Handle a detection event and choose what to do next.
25   * <p>The implementation behavior is to {@link
26   * Action#CONTINUE continue} propagation when ascending and to
27   * {@link Action#STOP stop} propagation when descending.</p>
28   *
29   * @author Hank Grabowski
30   *
31   * @since 6.1
32   */
33  public class StopOnDecreasing implements EventHandler {
34  
35      /** Empty constructor.
36       * <p>
37       * This constructor is not strictly necessary, but it prevents spurious
38       * javadoc warnings with JDK 18 and later.
39       * </p>
40       * @since 12.0
41       */
42      public StopOnDecreasing() {
43          // nothing to do
44      }
45  
46      /** Handle a detection event and choose what to do next.
47       * <p>The implementation behavior is to {@link
48       * Action#CONTINUE continue} propagation when ascending and to
49       * {@link Action#STOP stop} propagation when descending.</p>
50       * @param s the current state information : date, kinematics, attitude
51       * @param detector the detector object calling this method (not used in the evaluation)
52       * @param increasing if true, the value of the switching function increases
53       * when times increases around event
54       * @return {@link Action#STOP} or {@link Action#CONTINUE}
55       */
56      public Action eventOccurred(final SpacecraftState s, final EventDetector detector, final boolean increasing) {
57          return increasing ? Action.CONTINUE : Action.STOP;
58      }
59  
60  }