LOF.java

/* Copyright 2002-2025 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
 * limitations under the License.
 */
package org.orekit.frames;

import org.hipparchus.CalculusFieldElement;
import org.hipparchus.Field;
import org.hipparchus.analysis.differentiation.FieldUnivariateDerivative2;
import org.hipparchus.analysis.differentiation.FieldUnivariateDerivative2Field;
import org.hipparchus.analysis.differentiation.UnivariateDerivative2;
import org.hipparchus.analysis.differentiation.UnivariateDerivative2Field;
import org.hipparchus.geometry.euclidean.threed.FieldRotation;
import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
import org.hipparchus.geometry.euclidean.threed.Rotation;
import org.hipparchus.geometry.euclidean.threed.RotationConvention;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.AngularCoordinates;
import org.orekit.utils.FieldAngularCoordinates;
import org.orekit.utils.FieldPVCoordinates;
import org.orekit.utils.PVCoordinates;

/**
 * Interface for local orbital frame.
 *
 * @author Vincent Cucchietti
 */
public interface LOF {

    /**
     * Get the rotation from input to output {@link LOF local orbital frame}.
     * <p>
     * This rotation does not include any time derivatives. If first time derivatives (i.e. rotation rate) is needed as well,
     * the full {@link #transformFromLOFInToLOFOut(LOF, LOF, FieldAbsoluteDate, FieldPVCoordinates)} method must be called and
     * the complete rotation transform must be extracted from it.
     *
     * @param field field to which the elements belong
     * @param in input commonly used local orbital frame
     * @param out output commonly used local orbital frame
     * @param date date of the rotation
     * @param pv position-velocity of the spacecraft in some inertial frame
     * @param <T> type of the field elements
     *
     * @return rotation from input to output local orbital frame
     *
     * @since 11.3
     */
    static <T extends CalculusFieldElement<T>> FieldRotation<T> rotationFromLOFInToLOFOut(final Field<T> field,
                                                                                          final LOF in, final LOF out,
                                                                                          final FieldAbsoluteDate<T> date,
                                                                                          final FieldPVCoordinates<T> pv) {
        return out.rotationFromLOF(field, in, date, pv);
    }

    /**
     * Get the transform from input to output {@link LOF local orbital frame}.
     *
     * @param in input commonly used local orbital frame
     * @param out output commonly used local orbital frame
     * @param date date of the transform
     * @param pv position-velocity of the spacecraft in some inertial frame
     * @param <T> type of the field elements
     *
     * @return rotation from input to output local orbital frame.
     *
     * @since 11.3
     */
    static <T extends CalculusFieldElement<T>> FieldTransform<T> transformFromLOFInToLOFOut(final LOF in, final LOF out,
                                                                                            final FieldAbsoluteDate<T> date,
                                                                                            final FieldPVCoordinates<T> pv) {
        return out.transformFromLOF(in, date, pv);
    }

    /**
     * Get the rotation from input to output {@link LOF local orbital frame}.
     * <p>
     * This rotation does not include any time derivatives. If first time derivatives (i.e. rotation rate) is needed as well,
     * the full {@link #transformFromLOFInToLOFOut(LOF, LOF, AbsoluteDate, PVCoordinates)}   method must be called and
     * the complete rotation transform must be extracted from it.
     *
     * @param in input commonly used local orbital frame
     * @param out output commonly used local orbital frame
     * @param date date of the rotation
     * @param pv position-velocity of the spacecraft in some inertial frame
     *
     * @return rotation from input to output local orbital frame.
     *
     * @since 11.3
     */
    static Rotation rotationFromLOFInToLOFOut(final LOF in, final LOF out, final AbsoluteDate date, final PVCoordinates pv) {
        return out.rotationFromLOF(in, date, pv);
    }

    /**
     * Get the transform from input to output {@link LOF local orbital frame}.
     *
     * @param in input commonly used local orbital frame
     * @param out output commonly used local orbital frame
     * @param date date of the transform
     * @param pv position-velocity of the spacecraft in some inertial frame
     *
     * @return rotation from input to output local orbital frame
     *
     * @since 11.3
     */
    static Transform transformFromLOFInToLOFOut(final LOF in, final LOF out, final AbsoluteDate date,
                                                final PVCoordinates pv) {
        return out.transformFromLOF(in, date, pv);
    }

    /**
     * Get the rotation from input {@link LOF local orbital frame} to the instance.
     * <p>
     * This rotation does not include any time derivatives. If first time derivatives (i.e. rotation rate) is needed as well,
     * the full {@link #transformFromLOF(LOF, FieldAbsoluteDate, FieldPVCoordinates)}   method must be called and
     * the complete rotation transform must be extracted from it.
     *
     * @param field field to which the elements belong
     * @param fromLOF input local orbital frame
     * @param date date of the rotation
     * @param pv position-velocity of the spacecraft in some inertial frame
     * @param <T> type of the field elements
     *
     * @return rotation from input local orbital frame to the instance
     *
     * @since 11.3
     */
    default <T extends CalculusFieldElement<T>> FieldRotation<T> rotationFromLOF(final Field<T> field,
                                                                                 final LOF fromLOF,
                                                                                 final FieldAbsoluteDate<T> date,
                                                                                 final FieldPVCoordinates<T> pv) {

        // First compute the rotation from the input LOF to the pivot inertial
        final FieldRotation<T> fromLOFToInertial = fromLOF.rotationFromInertial(field, date, pv).revert();

        // Then compute the rotation from the pivot inertial to the output LOF
        final FieldRotation<T> inertialToThis = this.rotationFromInertial(field, date, pv);

        // Output composed rotation
        return fromLOFToInertial.compose(inertialToThis, RotationConvention.FRAME_TRANSFORM);
    }

    /**
     * Get the rotation from input {@link LOF commonly used local orbital frame} to the instance.
     *
     * @param fromLOF input local orbital frame
     * @param date date of the transform
     * @param pv position-velocity of the spacecraft in some inertial frame
     * @param <T> type of the field elements
     *
     * @return rotation from input local orbital frame to the instance
     *
     * @since 11.3
     */
    default <T extends CalculusFieldElement<T>> FieldTransform<T> transformFromLOF(final LOF fromLOF,
                                                                                   final FieldAbsoluteDate<T> date,
                                                                                   final FieldPVCoordinates<T> pv) {

        // Get transform from input local orbital frame to inertial
        final FieldTransform<T> fromLOFToInertial = fromLOF.transformFromInertial(date, pv).getInverse();

        // Get transform from inertial to output local orbital frame
        final FieldTransform<T> inertialToLOFOut = this.transformFromInertial(date, pv);

        // Output composition of both transforms
        return new FieldTransform<>(date, fromLOFToInertial, inertialToLOFOut);
    }

    /**
     * Get the transform from an inertial frame defining position-velocity and the local orbital frame.
     *
     * @param date current date
     * @param pv position-velocity of the spacecraft in some inertial frame
     * @param <T> type of the fields elements
     *
     * @return transform from the frame where position-velocity are defined to local orbital frame
     *
     * @since 9.0
     */
    default <T extends CalculusFieldElement<T>> FieldTransform<T> transformFromInertial(final FieldAbsoluteDate<T> date,
                                                                                        final FieldPVCoordinates<T> pv) {
        final Field<T> field = date.getField();
        if (isQuasiInertial()) {
            return new FieldTransform<>(date, pv.getPosition().negate(), rotationFromInertial(field, date, pv));

        } else if (pv.getAcceleration().equals(FieldVector3D.getZero(field))) {
            // we consider that the acceleration is not known
            // compute the translation part of the transform
            final FieldTransform<T> translation = new FieldTransform<>(date, pv.negate());

            // compute the rotation part of the transform
            final FieldRotation<T> r        = rotationFromInertial(date.getField(), date, pv);
            final FieldVector3D<T> p        = pv.getPosition();
            final FieldVector3D<T> momentum = pv.getMomentum();
            final FieldTransform<T> rotation = new FieldTransform<>(date, r,
                    new FieldVector3D<>(p.getNormSq().reciprocal(), r.applyTo(momentum)));

            return new FieldTransform<>(date, translation, rotation);

        } else {
            // use automatic differentiation
            // create date with independent variable
            final FieldUnivariateDerivative2Field<T> fud2Field = FieldUnivariateDerivative2Field.getUnivariateDerivative2Field(field);
            final FieldAbsoluteDate<FieldUnivariateDerivative2<T>> fud2Date = date.toFUD2Field();
            // create PV with independent variable
            final FieldPVCoordinates<FieldUnivariateDerivative2<T>> fud2PV = pv.toUnivariateDerivative2PV();
            // compute rotation
            final FieldRotation<FieldUnivariateDerivative2<T>> fud2Rotation = rotationFromInertial(fud2Field, fud2Date,
                fud2PV);
            // turn into FieldTransform whilst adding the translation
            final FieldAngularCoordinates<T> fieldAngularCoordinates = new FieldAngularCoordinates<>(fud2Rotation);
            return new FieldTransform<>(date, new FieldTransform<>(date, pv.negate()),
                new FieldTransform<>(date, fieldAngularCoordinates));
        }
    }

    /**
     * Get the rotation from inertial frame to local orbital frame.
     * <p>
     * This rotation does not include any time derivatives. If first time derivatives (i.e. rotation rate) is needed as well,
     * the full {@link #transformFromInertial(FieldAbsoluteDate, FieldPVCoordinates)} method must be
     * called and the complete rotation transform must be extracted from it.
     * </p>
     *
     * @param field field to which the elements belong
     * @param date date of the rotation
     * @param pv position-velocity of the spacecraft in some inertial frame
     * @param <T> type of the field elements
     *
     * @return rotation from inertial frame to local orbital frame
     *
     * @since 9.0
     */
    <T extends CalculusFieldElement<T>> FieldRotation<T> rotationFromInertial(Field<T> field, FieldAbsoluteDate<T> date,
                                                                              FieldPVCoordinates<T> pv);

    /**
     * Get the rotation from input {@link LOF local orbital frame} to the instance.
     * <p>
     * This rotation does not include any time derivatives. If first time derivatives (i.e. rotation rate) is needed as well,
     * the full {@link #transformFromLOF(LOF, AbsoluteDate, PVCoordinates)}  method must be called and
     * the complete rotation transform must be extracted from it.
     *
     * @param fromLOF input local orbital frame
     * @param date date of the rotation
     * @param pv position-velocity of the spacecraft in some inertial frame
     *
     * @return rotation from input local orbital frame to the instance
     *
     * @since 11.3
     */
    default Rotation rotationFromLOF(final LOF fromLOF, final AbsoluteDate date, final PVCoordinates pv) {

        // First compute the rotation from the input LOF to the pivot inertial
        final Rotation fromLOFToInertial = fromLOF.rotationFromInertial(date, pv).revert();

        // Then compute the rotation from the pivot inertial to the output LOF
        final Rotation inertialToThis = this.rotationFromInertial(date, pv);

        // Output composed rotation
        return fromLOFToInertial.compose(inertialToThis, RotationConvention.FRAME_TRANSFORM);
    }

    /**
     * Get the rotation from input {@link LOF local orbital frame} to the instance.
     *
     * @param fromLOF input local orbital frame
     * @param date date of the transform
     * @param pv position-velocity of the spacecraft in some inertial frame
     *
     * @return rotation from input local orbital frame to the instance
     *
     * @since 11.3
     */
    default Transform transformFromLOF(final LOF fromLOF, final AbsoluteDate date, final PVCoordinates pv) {

        // First compute the rotation from the input LOF to the pivot inertial
        final Transform fromLOFToInertial = fromLOF.transformFromInertial(date, pv).getInverse();

        // Then compute the rotation from the pivot inertial to the output LOF
        final Transform inertialToThis = this.transformFromInertial(date, pv);

        // Output composed rotation
        return new Transform(date, fromLOFToInertial, inertialToThis);
    }

    /**
     * Get the transform from an inertial frame defining position-velocity and the local orbital frame.
     *
     * @param date current date
     * @param pv position-velocity of the spacecraft in some inertial frame
     *
     * @return transform from the frame where position-velocity are defined to local orbital frame
     */
    default Transform transformFromInertial(final AbsoluteDate date, final PVCoordinates pv) {
        if (isQuasiInertial()) {
            return new Transform(date, pv.getPosition().negate(), rotationFromInertial(date, pv));

        } else if (pv.getAcceleration().equals(Vector3D.ZERO)) {
            // compute the rotation part of the transform assuming there is no known acceleration
            final Rotation  r        = rotationFromInertial(date, pv);
            final Vector3D  p        = pv.getPosition();
            final Vector3D  momentum = pv.getMomentum();
            final AngularCoordinates angularCoordinates = new AngularCoordinates(r,
                new Vector3D(1.0 / p.getNormSq(), r.applyTo(momentum)));

            return new Transform(date, pv.negate(), angularCoordinates);

        } else {
            // use automatic differentiation
            // create date with independent variable
            final UnivariateDerivative2Field ud2Field = UnivariateDerivative2Field.getInstance();
            final UnivariateDerivative2 dt = new UnivariateDerivative2(0, 1, 0);
            final FieldAbsoluteDate<UnivariateDerivative2> ud2Date = new FieldAbsoluteDate<>(ud2Field, date).shiftedBy(dt);
            // create PV with independent variable
            final FieldPVCoordinates<UnivariateDerivative2> ud2PVCoordinates = pv.toUnivariateDerivative2PV();
            // compute Field rotation
            final FieldRotation<UnivariateDerivative2> ud2Rotation = rotationFromInertial(ud2Field, ud2Date,
                ud2PVCoordinates);
            // turn into Transform whilst adding translation
            final AngularCoordinates angularCoordinates = new AngularCoordinates(ud2Rotation);
            return new Transform(date, pv.negate(), angularCoordinates);
        }
    }

    /**
     * Get the rotation from inertial frame to local orbital frame.
     * <p>
     * This rotation does not include any time derivatives. If first time derivatives (i.e. rotation rate) is needed as well,
     * the full {@link #transformFromInertial(AbsoluteDate, PVCoordinates) transformFromInertial} method must be called and
     * the complete rotation transform must be extracted from it.
     *
     * @param date date of the rotation
     * @param pv position-velocity of the spacecraft in some inertial frame
     *
     * @return rotation from inertial frame to local orbital frame
     */
    Rotation rotationFromInertial(AbsoluteDate date, PVCoordinates pv);

    /** Get flag that indicates if current local orbital frame shall be treated as pseudo-inertial.
     * @return flag that indicates if current local orbital frame shall be treated as pseudo-inertial
     */
    default boolean isQuasiInertial() {
        return false;
    }

    /** Get name of the local orbital frame.
     * @return name of the local orbital frame
     */
    String getName();

}