1   /* Copyright 2002-2025 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.attitudes;
18  
19  import org.hipparchus.CalculusFieldElement;
20  import org.orekit.frames.Frame;
21  import org.orekit.time.AbstractFieldTimeInterpolator;
22  import org.orekit.time.FieldTimeInterpolator;
23  import org.orekit.utils.TimeStampedFieldAngularCoordinates;
24  
25  import java.util.List;
26  import java.util.stream.Collectors;
27  import java.util.stream.Stream;
28  
29  /**
30   * Class for attitude interpolation.
31   * <p>
32   * The type of interpolation used is defined by given time stamped angular coordinates interpolator at construction.
33   *
34   * @param <KK> type of the field element
35   *
36   * @author Vincent Cucchietti
37   * @see TimeStampedFieldAngularCoordinates
38   * @see FieldTimeInterpolator
39   */
40  public class FieldAttitudeInterpolator<KK extends CalculusFieldElement<KK>>
41          extends AbstractFieldTimeInterpolator<FieldAttitude<KK>, KK> {
42  
43      /** Reference frame from which attitude is defined. */
44      private final Frame referenceFrame;
45  
46      /** Time stamped angular coordinates interpolator. */
47      private final FieldTimeInterpolator<TimeStampedFieldAngularCoordinates<KK>, KK> interpolator;
48  
49      /**
50       * Constructor.
51       *
52       * @param referenceFrame reference frame from which attitude is defined
53       * @param interpolator time stamped angular coordinates interpolator
54       */
55      public FieldAttitudeInterpolator(final Frame referenceFrame,
56                                       final FieldTimeInterpolator<TimeStampedFieldAngularCoordinates<KK>, KK> interpolator) {
57          super(interpolator.getNbInterpolationPoints(), interpolator.getExtrapolationThreshold());
58          this.referenceFrame = referenceFrame;
59          this.interpolator   = interpolator;
60      }
61  
62      /** Get reference frame from which attitude is defined.
63       * @return reference frame from which attitude is defined
64       */
65      public Frame getReferenceFrame() {
66          return referenceFrame;
67      }
68  
69      /** Get time stamped angular coordinates interpolator.
70       * @return time stamped angular coordinates interpolator
71       */
72      public FieldTimeInterpolator<TimeStampedFieldAngularCoordinates<KK>, KK> getAngularInterpolator() {
73          return interpolator;
74      }
75  
76      /** {@inheritDoc} */
77      @Override
78      protected FieldAttitude<KK> interpolate(final InterpolationData interpolationData) {
79  
80          // Convert sample to stream
81          final Stream<FieldAttitude<KK>> sample = interpolationData.getNeighborList().stream();
82  
83          // Express all attitudes in the same reference frame
84          final Stream<FieldAttitude<KK>> consistentSample =
85                  sample.map(attitude -> attitude.withReferenceFrame(referenceFrame));
86  
87          // Map time stamped angular coordinates
88          final List<TimeStampedFieldAngularCoordinates<KK>> angularSample =
89                  consistentSample.map(FieldAttitude::getOrientation).collect(Collectors.toList());
90  
91          // Interpolate
92          final TimeStampedFieldAngularCoordinates<KK> interpolated =
93                  interpolator.interpolate(interpolationData.getInterpolationDate(), angularSample);
94  
95          return new FieldAttitude<>(referenceFrame, interpolated);
96      }
97  }