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   * @param <T> class type for the generic version
32   * @since 6.1
33   */
34  public class StopOnDecreasing <T extends EventDetector> implements EventHandler<T> {
35  
36      /** Handle a detection event and choose what to do next.
37       * <p>The implementation behavior is to {@link
38       * Action#CONTINUE continue} propagation when ascending and to
39       * {@link Action#STOP stop} propagation when descending.</p>
40       * @param s the current state information : date, kinematics, attitude
41       * @param detector the detector object calling this method (not used in the evaluation)
42       * @param increasing if true, the value of the switching function increases
43       * when times increases around event
44       * @return {@link Action#STOP} or {@link Action#CONTINUE}
45       */
46      public Action eventOccurred(final SpacecraftState s, final T detector, final boolean increasing) {
47          return increasing ? Action.CONTINUE : Action.STOP;
48      }
49  
50  }