1   /* Copyright 2002-2024 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.models.earth.weather;
18  
19  import java.util.List;
20  import java.util.SortedSet;
21  
22  import org.hipparchus.CalculusFieldElement;
23  import org.hipparchus.util.FastMath;
24  import org.hipparchus.util.MathUtils;
25  import org.orekit.errors.OrekitException;
26  import org.orekit.errors.OrekitMessages;
27  
28  /** Container for a complete grid.
29   * @author Bryan Cazabonne
30   * @author Luc Maisonobe
31   * @since 12.1
32   */
33  class Grid {
34  
35      /** Latitude sample. */
36      private final SortedSet<Integer> latitudeSample;
37  
38      /** Longitude sample. */
39      private final SortedSet<Integer> longitudeSample;
40  
41      /** Grid entries. */
42      private final GridEntry[][] entries;
43  
44      /** Simple constructor.
45       * @param latitudeSample latitude sample
46       * @param longitudeSample longitude sample
47       * @param loadedEntries loaded entries, organized as a simple list
48       * @param name file name
49       */
50      Grid(final SortedSet<Integer> latitudeSample, final SortedSet<Integer> longitudeSample,
51           final List<GridEntry> loadedEntries, final String name) {
52  
53          final int nA         = latitudeSample.size();
54          final int nO         = longitudeSample.size() + 1; // we add one here for wrapping the grid
55          this.entries         = new GridEntry[nA][nO];
56          this.latitudeSample  = latitudeSample;
57          this.longitudeSample = longitudeSample;
58  
59          // organize entries in the regular grid
60          for (final GridEntry entry : loadedEntries) {
61              final int latitudeIndex  = latitudeSample.headSet(entry.getLatKey() + 1).size() - 1;
62              final int longitudeIndex = longitudeSample.headSet(entry.getLonKey() + 1).size() - 1;
63              entries[latitudeIndex][longitudeIndex] = entry;
64          }
65  
66          // finalize the grid
67          for (final GridEntry[] row : entries) {
68  
69              // check for missing entries
70              for (int longitudeIndex = 0; longitudeIndex < nO - 1; ++longitudeIndex) {
71                  if (row[longitudeIndex] == null) {
72                      throw new OrekitException(OrekitMessages.IRREGULAR_OR_INCOMPLETE_GRID, name);
73                  }
74              }
75  
76              // wrap the grid around the Earth in longitude
77              row[nO - 1] = row[0].buildWrappedEntry();
78  
79          }
80  
81      }
82  
83      /** Get index of South entries in the grid.
84       * @param latitude latitude to locate (radians)
85       * @return index of South entries in the grid
86       */
87      private int getSouthIndex(final double latitude) {
88  
89          final int latKey = (int) FastMath.rint(FastMath.toDegrees(latitude) * GridEntry.DEG_TO_MAS);
90          final int index  = latitudeSample.headSet(latKey + 1).size() - 1;
91  
92          // make sure we have at least one point remaining on North by clipping to size - 2
93          return FastMath.min(index, latitudeSample.size() - 2);
94  
95      }
96  
97      /** Get index of West entries in the grid.
98       * @param longitude longitude to locate (radians)
99       * @return index of West entries in the grid
100      */
101     private int getWestIndex(final double longitude) {
102 
103         final int lonKey = (int) FastMath.rint(FastMath.toDegrees(longitude) * GridEntry.DEG_TO_MAS);
104         final int index  = longitudeSample.headSet(lonKey + 1).size() - 1;
105 
106         // we don't do clipping in longitude because we have added a row to wrap around the Earth
107         return index;
108 
109     }
110 
111     /** Get interpolator within a cell.
112      * @param latitude latitude of point of interest
113      * @param longitude longitude of point of interest
114      * @return interpolator for the cell
115      */
116     CellInterpolator getInterpolator(final double latitude, final double longitude) {
117 
118         // keep longitude within grid range
119         final double normalizedLongitude =
120                         MathUtils.normalizeAngle(longitude,
121                                                  entries[0][0].getLongitude() + FastMath.PI);
122 
123         // find neighboring grid entries
124         final int southIndex = getSouthIndex(latitude);
125         final int westIndex  = getWestIndex(normalizedLongitude);
126 
127         // build interpolator
128         return new CellInterpolator(latitude, normalizedLongitude,
129                                     entries[southIndex    ][westIndex    ],
130                                     entries[southIndex    ][westIndex + 1],
131                                     entries[southIndex + 1][westIndex    ],
132                                     entries[southIndex + 1][westIndex + 1]);
133 
134     }
135 
136     /** Get interpolator within a cell.
137      * @param <T> type of the field elements
138      * @param latitude latitude of point of interest
139      * @param longitude longitude of point of interest
140      * @return interpolator for the cell
141      */
142     <T extends CalculusFieldElement<T>> FieldCellInterpolator<T> getInterpolator(final T latitude, final T longitude) {
143 
144         // keep longitude within grid range
145         final T normalizedLongitude =
146                         MathUtils.normalizeAngle(longitude,
147                                                  longitude.newInstance(entries[0][0].getLongitude() + FastMath.PI));
148 
149         // find neighboring grid entries
150         final int southIndex = getSouthIndex(latitude.getReal());
151         final int westIndex  = getWestIndex(normalizedLongitude.getReal());
152 
153         // build interpolator
154         return new FieldCellInterpolator<>(latitude, normalizedLongitude,
155                                            entries[southIndex    ][westIndex    ],
156                                            entries[southIndex    ][westIndex + 1],
157                                            entries[southIndex + 1][westIndex    ],
158                                            entries[southIndex + 1][westIndex + 1]);
159 
160     }
161 
162     /** Check if grid contains all specified models.
163      * @param types models types
164      * @return true if grid contain the model
165      */
166     boolean hasModels(final SeasonalModelType... types) {
167         boolean hasAll = true;
168         for (final SeasonalModelType type : types) {
169             hasAll &= entries[0][0].getModel(type) != null;
170         }
171         return hasAll;
172     }
173 
174 }