AbstractLightFluxModel.java
/* Copyright 2022-2024 Romain Serra
* 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.forces.radiation;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.orekit.frames.Frame;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.propagation.SpacecraftState;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.ExtendedPositionProvider;
/**
* Abstract class for light flux models.
* Via the definition of the lighting ratio and the unocculted flux vector, derives the final value.
*
* @author Romain Serra
* @see LightFluxModel
* @since 12.1
*/
public abstract class AbstractLightFluxModel implements LightFluxModel {
/** Direction provider for the occulted body e.g. the Sun. */
private final ExtendedPositionProvider occultedBody;
/**
* Constructor.
* @param occultedBody position provider for light source
*/
protected AbstractLightFluxModel(final ExtendedPositionProvider occultedBody) {
this.occultedBody = occultedBody;
}
/**
* Getter for the occulted body's position provider.
* @return occulted body
*/
public ExtendedPositionProvider getOccultedBody() {
return occultedBody;
}
/** {@inheritDoc} */
@Override
public Vector3D getLightFluxVector(final SpacecraftState state) {
final Vector3D position = state.getPosition();
final Vector3D lightSourcePosition = getOccultedBodyPosition(state.getDate(), state.getFrame());
final double lightingRatio = getLightingRatio(position, lightSourcePosition);
if (lightingRatio != 0.) {
final Vector3D relativePosition = position.subtract(lightSourcePosition);
final Vector3D unoccultedFlux = getUnoccultedFluxVector(relativePosition);
return unoccultedFlux.scalarMultiply(lightingRatio);
} else {
return Vector3D.ZERO;
}
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> FieldVector3D<T> getLightFluxVector(final FieldSpacecraftState<T> state) {
final FieldVector3D<T> position = state.getPosition();
final FieldVector3D<T> lightSourcePosition = getOccultedBodyPosition(state.getDate(), state.getFrame());
final T lightingRatio = getLightingRatio(position, lightSourcePosition);
final FieldVector3D<T> relativePosition = position.subtract(lightSourcePosition);
final FieldVector3D<T> unoccultedFlux = getUnoccultedFluxVector(relativePosition);
return unoccultedFlux.scalarMultiply(lightingRatio);
}
/**
* Method computing the occulted body's position at a given date and frame.
* @param date date
* @param frame frame
* @return position
*/
protected Vector3D getOccultedBodyPosition(final AbsoluteDate date, final Frame frame) {
return occultedBody.getPosition(date, frame);
}
/**
* Method computing the occulted body's position at a given date and frame. Field version.
* @param date date
* @param frame frame
* @param <T> field type
* @return position
*/
protected <T extends CalculusFieldElement<T>> FieldVector3D<T> getOccultedBodyPosition(final FieldAbsoluteDate<T> date,
final Frame frame) {
return occultedBody.getPosition(date, frame);
}
/** Get the light flux vector, not considering any shadowing effect.
* @param relativePosition relative position w.r.t. light source
* @return unocculted flux
*/
protected abstract Vector3D getUnoccultedFluxVector(Vector3D relativePosition);
/** Get the light flux vector, not considering any shadowing effect. Field version.
* @param relativePosition relative position w.r.t. light source
* @param <T> field type
* @return unocculted flux
*/
protected abstract <T extends CalculusFieldElement<T>> FieldVector3D<T> getUnoccultedFluxVector(FieldVector3D<T> relativePosition);
/** Get the lighting ratio ([0-1]).
* @param state state
* @return lighting ratio
*/
public double getLightingRatio(final SpacecraftState state) {
final Vector3D position = state.getPosition();
final Vector3D lightSourcePosition = getOccultedBodyPosition(state.getDate(), state.getFrame());
return getLightingRatio(position, lightSourcePosition);
}
/** Get the lighting ratio ([0-1]).
* @param position object's position
* @param occultedBodyPosition occulted body position in same frame
* @return lighting ratio
*/
protected abstract double getLightingRatio(Vector3D position, Vector3D occultedBodyPosition);
/** Get the lighting ratio ([0-1]).
* @param state state
* @param <T> field type
* @return lighting ratio
*/
public <T extends CalculusFieldElement<T>> T getLightingRatio(final FieldSpacecraftState<T> state) {
final FieldVector3D<T> position = state.getPosition();
final FieldVector3D<T> lightSourcePosition = getOccultedBodyPosition(state.getDate(), state.getFrame());
return getLightingRatio(position, lightSourcePosition);
}
/** Get the lighting ratio ([0-1]). Field version.
* @param position object's position
* @param occultedBodyPosition occulted body position in same frame
* @param <T> field type
* @return lighting ratio
*/
protected abstract <T extends CalculusFieldElement<T>> T getLightingRatio(FieldVector3D<T> position,
FieldVector3D<T> occultedBodyPosition);
}