1   /* Copyright 2022-2025 Romain Serra
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.forces.radiation;
18  
19  import org.hipparchus.CalculusFieldElement;
20  import org.hipparchus.Field;
21  import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
22  import org.hipparchus.geometry.euclidean.threed.Vector3D;
23  import org.orekit.propagation.FieldSpacecraftState;
24  import org.orekit.propagation.SpacecraftState;
25  import org.orekit.propagation.events.EventDetector;
26  import org.orekit.propagation.events.FieldEventDetector;
27  import org.orekit.time.AbsoluteDate;
28  import org.orekit.time.FieldAbsoluteDate;
29  
30  import java.util.List;
31  
32  /**
33   * Interface describing flux models from a light source, including shadowing effects from occulting bodies.
34   * Defines the flux vector itself as well as detectors for entry and exit of the different eclipse zones, if any.
35   *
36   * @author Romain Serra
37   * @since 12.1
38   */
39  public interface LightFluxModel {
40  
41      /**
42       * Perform initialization steps before starting propagation.
43       * @param initialState initial state
44       * @param targetDate target date for propagation
45       * @since 12.2
46       */
47      default void init(SpacecraftState initialState, final AbsoluteDate targetDate) {
48          // nothing by default
49      }
50  
51      /**
52       * Perform initialization steps before starting propagation.
53       * @param initialState initial state
54       * @param targetDate target date for propagation
55       * @param <T> field type
56       * @since 12.2
57       */
58      default <T extends CalculusFieldElement<T>> void init(FieldSpacecraftState<T> initialState,
59                                                            final FieldAbsoluteDate<T> targetDate) {
60          // nothing by default
61      }
62  
63      /**
64       * Get the light flux vector in the state's frame.
65       * @param state state
66       * @return light flux
67       */
68      Vector3D getLightFluxVector(SpacecraftState state);
69  
70      /**
71       * Get the light flux vector in the state's frame. Field version.
72       * @param state state
73       * @return light flux
74       * @param <T> field type
75       */
76      <T extends CalculusFieldElement<T>> FieldVector3D<T> getLightFluxVector(FieldSpacecraftState<T> state);
77  
78      /**
79       * Retrieve detectors finding entries and exits in different eclipse zones.
80       * @return list of event detectors
81       */
82      List<EventDetector> getEclipseConditionsDetector();
83  
84      /**
85       * Retrieve Field detectors finding entries and exits in different eclipse zones.
86       * @param field calculus field
87       * @return list of event detectors
88       * @param <T> field type
89       */
90      <T extends CalculusFieldElement<T>> List<FieldEventDetector<T>> getFieldEclipseConditionsDetector(Field<T> field);
91  }