1   /* Copyright 2002-2020 CS Group
2    * Licensed to CS Group (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;
18  
19  import org.hipparchus.util.FastMath;
20  
21  /** Enumerate for triggering visibility of spherical bodies.
22   * @see CircularFieldOfViewDetector
23   * @see FieldOfViewDetector
24   * @author Luc Maisonobe
25   * @since 10.0
26   */
27  public enum VisibilityTrigger {
28  
29      /** Trigger for bodies that are considered visible only when fully inside Field Of View. */
30      VISIBLE_ONLY_WHEN_FULLY_IN_FOV(+1.0),
31  
32      /** Trigger for bodies that are considered visible as soon as a part touches Field Of View. */
33      VISIBLE_AS_SOON_AS_PARTIALLY_IN_FOV(-1.0);
34  
35      /** Sign of the radius correction. */
36      private final double sign;
37  
38      /** Simple constructor.
39       * @param sign sign of the radius correction
40       */
41      VisibilityTrigger(final double sign) {
42          this.sign = sign;
43      }
44  
45      /** Apply radius correction.
46       * @param angularRadius target body angular radius
47       * @return corrected radius
48       * @since 10.1
49       */
50      public double radiusCorrection(final double angularRadius) {
51          return FastMath.copySign(angularRadius, sign);
52      }
53  
54  }