edu.mit.fss.tutorial.part2.MobileElement.java Source code

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Here is the source code for edu.mit.fss.tutorial.part2.MobileElement.java

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/*
 * Copyright 2015 Paul T. Grogan
 * 
 * Licensed 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 edu.mit.fss.tutorial.part2;

import java.util.ArrayList;
import java.util.Collection;

import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;

import edu.mit.fss.ReferenceFrame;
import edu.mit.fss.SimObject;
import edu.mit.fss.SurfaceElement;

/**
 * A simple surface element which updates position using (inaccurate) 
 * Euler integration of velocity and reports geodetic coordinates 
 * using an (inaccurate) spherical Earth model.
 * 
 * @author Paul T. Grogan, ptgrogan@mit.edu
 * @version 0.2.0
 * @since 0.1.0
 */
public class MobileElement implements SurfaceElement {
    private String name;
    private Vector3D position, nextPosition, initialPosition;
    private Vector3D velocity, nextVelocity, initialVelocity;

    /**
     * Instantiates a new mobile element.
     *
     * @param name the name
     */
    public MobileElement(String name, Vector3D initialVelocity) {
        this.name = name;
        position = new Vector3D(0, 0, 0);
        initialPosition = new Vector3D(0, 0, 0);
        velocity = new Vector3D(0, 0, 0);
        this.initialVelocity = initialVelocity;
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.SurfaceElement#getAltitude()
     */
    @Override
    public double getAltitude() {
        return position.getNorm() - 6371e3;
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.Element#getFrame()
     */
    @Override
    public ReferenceFrame getFrame() {
        return ReferenceFrame.ITRF2008;
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.SurfaceElement#getLatitude()
     */
    @Override
    public double getLatitude() {
        return Math.toDegrees(Math.atan2(position.getZ(), position.getX()));
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.SurfaceElement#getLongitude()
     */
    @Override
    public double getLongitude() {
        return Math.toDegrees(Math.atan2(position.getY(), position.getX()));
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.SimObject#getName()
     */
    @Override
    public String getName() {
        return name;
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.SimObject#getNestedObjects()
     */
    @Override
    public Collection<? extends SimObject> getNestedObjects() {
        return new ArrayList<SimObject>();
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.Element#getPosition()
     */
    @Override
    public Vector3D getPosition() {
        return position;
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.Element#getVelocity()
     */
    @Override
    public Vector3D getVelocity() {
        return velocity;
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.SimObject#initialize(long)
     */
    @Override
    public void initialize(long time) {
        position = initialPosition;
        nextPosition = initialPosition;
        velocity = initialVelocity;
        nextVelocity = initialVelocity;
    }

    /**
     * Sets the velocity.
     *
     * @param velocity the new velocity
     */
    public void setVelocity(Vector3D velocity) {
        nextVelocity = velocity;
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.SimObject#tick(long)
     */
    @Override
    public void tick(long duration) {
        nextPosition = position.add(velocity.scalarMultiply(duration / 1000d));
    }

    /* (non-Javadoc)
     * @see edu.mit.fss.SimObject#tock()
     */
    @Override
    public void tock() {
        position = nextPosition;
        velocity = nextVelocity;
    }
}