MultisatStepNormalizer.java
- /* Copyright 2002-2024 Luc Maisonobe
- * 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.propagation.sampling;
- import java.util.ArrayList;
- import java.util.List;
- import java.util.stream.Collectors;
- import org.hipparchus.util.FastMath;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.time.AbsoluteDate;
- /**
- * This class wraps an object implementing {@link MultiSatFixedStepHandler}
- * into a {@link MultiSatStepHandler}.
- * <p>It mirrors the <code>StepNormalizer</code> interface from <a
- * href="https://hipparchus.org/">Hipparchus</a> but
- * provides a space-dynamics interface to the methods.</p>
- * @author Luc Maisonobe
- * @since 12.0
- */
- public class MultisatStepNormalizer implements MultiSatStepHandler {
- /** Fixed time step. */
- private double h;
- /** Underlying fixed step handler. */
- private MultiSatFixedStepHandler handler;
- /** Last State vectors. */
- private List<SpacecraftState> lastStates;
- /** Integration direction indicator. */
- private boolean forward;
- /** Simple constructor.
- * @param h fixed time step (sign is not used)
- * @param handler fixed time step handler to wrap
- */
- public MultisatStepNormalizer(final double h, final MultiSatFixedStepHandler handler) {
- this.h = FastMath.abs(h);
- this.handler = handler;
- this.lastStates = null;
- this.forward = true;
- }
- /** Get the fixed time step.
- * @return fixed time step
- */
- public double getFixedTimeStep() {
- return h;
- }
- /** Get the underlying fixed step handler.
- * @return underlying fixed step handler
- */
- public MultiSatFixedStepHandler getFixedStepHandler() {
- return handler;
- }
- /** {@inheritDoc} */
- public void init(final List<SpacecraftState> s0, final AbsoluteDate t) {
- lastStates = new ArrayList<>(s0);
- forward = true;
- handler.init(s0, t, h);
- }
- /** {@inheritDoc} */
- public void handleStep(final List<OrekitStepInterpolator> interpolators) {
- if (lastStates == null) {
- // initialize lastState in the first step case
- lastStates = interpolators.stream().map(i -> i.getPreviousState()).collect(Collectors.toList());
- }
- // take the propagation direction into account
- double step = h;
- forward = interpolators.get(0).isForward();
- if (!forward) {
- step = -h;
- }
- // use the interpolator to push fixed steps events to the underlying handler
- AbsoluteDate nextTime = lastStates.get(0).getDate().shiftedBy(step);
- boolean nextInStep = forward ^ nextTime.compareTo(interpolators.get(0).getCurrentState().getDate()) > 0;
- while (nextInStep) {
- // output the stored previous step
- handler.handleStep(lastStates);
- // store the next step
- final AbsoluteDate time = nextTime;
- lastStates = interpolators.stream().map(i -> i.getInterpolatedState(time)).collect(Collectors.toList());
- // prepare next iteration
- nextTime = nextTime.shiftedBy(step);
- nextInStep = forward ^ nextTime.compareTo(interpolators.get(0).getCurrentState().getDate()) > 0;
- }
- }
- /** {@inheritDoc} */
- @Override
- public void finish(final List<SpacecraftState> finalStates) {
- // there will be no more steps,
- // the stored one should be handled now
- handler.handleStep(lastStates);
- // and the final state handled too
- handler.finish(finalStates);
- }
- }