FieldAbstractRelativeProvider.java

/* Copyright 2002-2026 CS GROUP
 * Licensed to CS GROUP (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
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 */
package org.orekit.propagation.relative;

import org.hipparchus.CalculusFieldElement;
import org.orekit.frames.FieldTransform;
import org.orekit.frames.Frame;
import org.orekit.frames.LOF;
import org.orekit.orbits.FieldOrbit;
import org.orekit.utils.TimeStampedFieldPVCoordinates;

/**
 * Abstraction class for Field RelativeProvider.
 *
 * @param <T> Any scalar field.
 * @author Romain Cuvillon
 * @since 14.0
 */
public abstract class FieldAbstractRelativeProvider<T extends CalculusFieldElement<T>>
                implements FieldRelativeProvider<T> {

    /**
     * Additional equations name.
     */
    private final String additionalEquationsName;

    /**
     * Initial chaser PVT in the target's LOF.
     */
    private TimeStampedFieldPVCoordinates<T> initialChaserPVTLof;

    /**
     * Target's orbit.
     */
    private FieldOrbit<T> targetOrbit;

    /**
     * Local Orbital Frame.
     */
    private final LOF lof;

    /**
     * Builds a new RelativeProvider object from the target orbit and an initial PVT of the chaser.
     *
     * @param targetOrbit             Target orbit
     * @param initialChaserPVTLof     Chaser PVT in the target's  local orbital frame
     * @param additionalEquationsName Additional equations name
     * @param lof                     Local Orbital Frame
     */
    public FieldAbstractRelativeProvider(final FieldOrbit<T> targetOrbit,
                                         final TimeStampedFieldPVCoordinates<T> initialChaserPVTLof,
                                         final String additionalEquationsName,
                                         final LOF lof) {
        this.targetOrbit             = targetOrbit;
        this.initialChaserPVTLof     = initialChaserPVTLof;
        this.additionalEquationsName = additionalEquationsName;
        this.lof                     = lof;
    }

    /**
     * Builds a new Relativeprovider object from the target orbit and an initial PVT of the chaser expressed in
     * the given input frame.
     *
     * @param targetOrbit             Target orbit. Should be circular for better results
     * @param initialChaserPVT        Chaser PVT in given frame
     * @param inputPVTFrame           Input frame for the initial chaser PVT
     * @param additionalEquationsName Additional equations name
     * @param lof                     Local Orbital Frame
     */
    public FieldAbstractRelativeProvider(final FieldOrbit<T> targetOrbit,
                                         final TimeStampedFieldPVCoordinates<T> initialChaserPVT,
                                         final Frame inputPVTFrame,
                                         final String additionalEquationsName,
                                         final LOF lof) {
        // Copy input parameters
        this.targetOrbit             = targetOrbit;
        this.additionalEquationsName = additionalEquationsName;
        this.lof                     = lof;

        // Transform PV from input frame to inertial frame of target Orbit.
        final FieldTransform<T> inputFrameToInertial = inputPVTFrame.getTransformTo(targetOrbit.getFrame(),
                                                                                    targetOrbit.getDate());
        final TimeStampedFieldPVCoordinates<T> pvInertial = inputFrameToInertial.transformPVCoordinates(initialChaserPVT);

        // Transform and set PV from inertial to target's LOF.
        setInitialChaserPVTLof(getLof().transformFromInertial(targetOrbit.getDate(),
                                                              targetOrbit.getPVCoordinates())
                                       .transformPVCoordinates(pvInertial));
    }

    /** {@inheritDoc}. */
    @Override
    public LOF getLof() {
        return lof;
    }

    /** {@inheritDoc}. */
    @Override
    public void setInitialChaserPVTLof(final TimeStampedFieldPVCoordinates<T> initialChaserPVTLof) {
        this.initialChaserPVTLof = initialChaserPVTLof;
    }

    /** {@inheritDoc}. */
    @Override
    public TimeStampedFieldPVCoordinates<T> getInitialChaserPVTLof() {
        return initialChaserPVTLof;
    }

    /** {@inheritDoc}. */
    @Override
    public String getName() {
        return additionalEquationsName;
    }

    /** {@inheritDoc}. */
    @Override
    public FieldOrbit<T> getTargetOrbit() {
        return targetOrbit;
    }

    /** {@inheritDoc}. */
    @Override
    public void setTargetOrbit(final FieldOrbit<T> targetOrbit) {
        this.targetOrbit = targetOrbit;
    }
}