1   /* Copyright 2022-2025 Luc Maisonobe
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  
18  package org.orekit.utils;
19  
20  import org.hipparchus.geometry.euclidean.threed.Vector3D;
21  import org.orekit.frames.Frame;
22  import org.orekit.time.AbsoluteDate;
23  
24  /** Provider using simple {@link PVCoordinates#shiftedBy(double)}  shiftedBy} and frame transforms for evolution.
25   * @author Luc Maisonobe
26   * @since 12.1
27   */
28  public class ShiftingPVCoordinatesProvider implements PVCoordinatesProvider {
29  
30      /** Reference coordinates. */
31      private final TimeStampedPVCoordinates referencePV;
32  
33      /** Frame in which {@link #referencePV} is defined. */
34      private final Frame referenceFrame;
35  
36      /** Simple constructor.
37       * @param referencePV reference coordinates
38       * @param referenceFrame frame in which {@code reference} is defined
39       */
40      public ShiftingPVCoordinatesProvider(final TimeStampedPVCoordinates referencePV,
41                                           final Frame referenceFrame) {
42          this.referencePV    = referencePV;
43          this.referenceFrame = referenceFrame;
44      }
45  
46      /** {@inheritDoc} */
47      @Override
48      public TimeStampedPVCoordinates getPVCoordinates(final AbsoluteDate date,
49                                                       final Frame frame) {
50          final TimeStampedPVCoordinates shifted = referencePV.shiftedBy(date.durationFrom(referencePV));
51          return referenceFrame.getTransformTo(frame, date).transformPVCoordinates(shifted);
52      }
53  
54      /** {@inheritDoc} */
55      @Override
56      public Vector3D getPosition(final AbsoluteDate date, final Frame frame) {
57          final double duration = date.durationFrom(referencePV);
58          final Vector3D position = referencePV.getPosition().add((referencePV.getVelocity().add(referencePV.getAcceleration().scalarMultiply(duration / 2))).scalarMultiply(duration));
59          return referenceFrame.getStaticTransformTo(frame, date).transformPosition(position);
60      }
61  }