TabulatedLofOffset.java
/* Copyright 2002-2019 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.attitudes;
import java.io.NotSerializableException;
import java.io.Serializable;
import java.util.List;
import java.util.stream.Collectors;
import org.hipparchus.RealFieldElement;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitInternalError;
import org.orekit.errors.OrekitMessages;
import org.orekit.frames.FieldTransform;
import org.orekit.frames.Frame;
import org.orekit.frames.LOFType;
import org.orekit.frames.Transform;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.AngularDerivativesFilter;
import org.orekit.utils.FieldPVCoordinates;
import org.orekit.utils.FieldPVCoordinatesProvider;
import org.orekit.utils.ImmutableTimeStampedCache;
import org.orekit.utils.PVCoordinates;
import org.orekit.utils.PVCoordinatesProvider;
import org.orekit.utils.TimeStampedAngularCoordinates;
import org.orekit.utils.TimeStampedFieldAngularCoordinates;
/**
* This class handles an attitude provider interpolating from a predefined table
* containing offsets from a Local Orbital Frame.
* <p>Instances of this class are guaranteed to be immutable.</p>
* @see LofOffset
* @see TabulatedProvider
* @author Luc Maisonobe
* @since 7.1
*/
public class TabulatedLofOffset implements AttitudeProvider {
/** Serializable UID. */
private static final long serialVersionUID = 20151211L;
/** Inertial frame with respect to which orbit should be computed. */
private final Frame inertialFrame;
/** Type of Local Orbital Frame. */
private LOFType type;
/** Cached attitude table. */
private final transient ImmutableTimeStampedCache<TimeStampedAngularCoordinates> table;
/** Filter for derivatives from the sample to use in interpolation. */
private final AngularDerivativesFilter filter;
/** Creates new instance.
* @param inertialFrame inertial frame with respect to which orbit should be computed
* @param type type of Local Orbital Frame
* @param table tabulated attitudes
* @param n number of attitude to use for interpolation
* @param filter filter for derivatives from the sample to use in interpolation
*/
public TabulatedLofOffset(final Frame inertialFrame, final LOFType type,
final List<TimeStampedAngularCoordinates> table,
final int n, final AngularDerivativesFilter filter) {
if (!inertialFrame.isPseudoInertial()) {
throw new OrekitException(OrekitMessages.NON_PSEUDO_INERTIAL_FRAME,
inertialFrame.getName());
}
this.inertialFrame = inertialFrame;
this.type = type;
this.table = new ImmutableTimeStampedCache<TimeStampedAngularCoordinates>(n, table);
this.filter = filter;
}
/** Get an unmodifiable view of the tabulated attitudes.
* @return unmodifiable view of the tabulated attitudes
*/
public List<TimeStampedAngularCoordinates> getTable() {
return table.getAll();
}
/** {@inheritDoc} */
public Attitude getAttitude(final PVCoordinatesProvider pvProv,
final AbsoluteDate date, final Frame frame) {
// get attitudes sample on which interpolation will be performed
final List<TimeStampedAngularCoordinates> sample = table.getNeighbors(date).collect(Collectors.toList());
// interpolate
final TimeStampedAngularCoordinates interpolated =
TimeStampedAngularCoordinates.interpolate(date, filter, sample);
// construction of the local orbital frame, using PV from inertial frame
final PVCoordinates pv = pvProv.getPVCoordinates(date, inertialFrame);
final Transform inertialToLof = type.transformFromInertial(date, pv);
// take into account the specified start frame (which may not be an inertial one)
final Transform frameToInertial = frame.getTransformTo(inertialFrame, date);
final Transform frameToLof = new Transform(date, frameToInertial, inertialToLof);
// compose with interpolated rotation
return new Attitude(date, frame,
interpolated.addOffset(frameToLof.getAngular()));
}
/** {@inheritDoc} */
public <T extends RealFieldElement<T>> FieldAttitude<T> getAttitude(final FieldPVCoordinatesProvider<T> pvProv,
final FieldAbsoluteDate<T> date,
final Frame frame) {
// get attitudes sample on which interpolation will be performed
final List<TimeStampedFieldAngularCoordinates<T>> sample =
table.
getNeighbors(date.toAbsoluteDate()).
map(ac -> new TimeStampedFieldAngularCoordinates<>(date.getField(), ac)).
collect(Collectors.toList());
// interpolate
final TimeStampedFieldAngularCoordinates<T> interpolated =
TimeStampedFieldAngularCoordinates.interpolate(date, filter, sample);
// construction of the local orbital frame, using PV from inertial frame
final FieldPVCoordinates<T> pv = pvProv.getPVCoordinates(date, inertialFrame);
final FieldTransform<T> inertialToLof = type.transformFromInertial(date, pv);
// take into account the specified start frame (which may not be an inertial one)
final FieldTransform<T> frameToInertial = frame.getTransformTo(inertialFrame, date);
final FieldTransform<T> frameToLof = new FieldTransform<>(date, frameToInertial, inertialToLof);
// compose with interpolated rotation
return new FieldAttitude<>(date, frame,
interpolated.addOffset(frameToLof.getAngular()));
}
/** Replace the instance with a data transfer object for serialization.
* @return data transfer object that will be serialized
* @exception NotSerializableException if the state mapper cannot be serialized (typically for DSST propagator)
*/
private Object writeReplace() throws NotSerializableException {
return new DataTransferObject(inertialFrame, type, table.getAll(), table.getNeighborsSize(), filter);
}
/** Internal class used only for serialization. */
private static class DataTransferObject implements Serializable {
/** Serializable UID. */
private static final long serialVersionUID = 20151211L;
/** Inertial frame with respect to which orbit should be computed. */
private final Frame inertialFrame;
/** Type of Local Orbital Frame. */
private LOFType type;
/** Cached attitude table. */
private final List<TimeStampedAngularCoordinates> list;
/** Number of attitude to use for interpolation. */
private final int n;
/** Filter for derivatives from the sample to use in interpolation. */
private final AngularDerivativesFilter filter;
/** Simple constructor.
* @param inertialFrame inertial frame with respect to which orbit should be computed
* @param type type of Local Orbital Frame
* @param list tabulated attitudes
* @param n number of attitude to use for interpolation
* @param filter filter for derivatives from the sample to use in interpolation
*/
DataTransferObject(final Frame inertialFrame, final LOFType type,
final List<TimeStampedAngularCoordinates> list,
final int n, final AngularDerivativesFilter filter) {
this.inertialFrame = inertialFrame;
this.type = type;
this.list = list;
this.n = n;
this.filter = filter;
}
/** Replace the deserialized data transfer object with a {@link TabulatedLofOffset}.
* @return replacement {@link TabulatedLofOffset}
*/
private Object readResolve() {
try {
return new TabulatedLofOffset(inertialFrame, type, list, n, filter);
} catch (OrekitException oe) {
// this should never happen
throw new OrekitInternalError(oe);
}
}
}
}