253 lines
9.5 KiB
Java
253 lines
9.5 KiB
Java
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/*
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File: KeplerEquation.java
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University of Applied Science Berne,HTA-Biel/Bienne,
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Computer Science Department.
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Diploma thesis J3D Solar System Simulator
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Originally written by Marcel Portner & Bernhard Hari (c) 2000
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CVS - Information :
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$Header: /var/cvsreps/projects/c450/2000/sss3d/source_diploma/sss3d/calculations/keplerequation/KeplerEquation.java,v 1.10 2000/12/13 13:36:38 portm Exp $
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$Author: portm $
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$Date: 2000/12/13 13:36:38 $
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$State: Exp $
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*/
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package sss3d.calculations.keplerequation;
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import sss3d.calculations.constants.AstronomicalConstants;
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import sss3d.utils.SSS3dConstants;
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import sss3d.utils.astronomy.*;
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import sss3d.calculations.*;
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import sss3d.contentbranch.*;
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import javax.vecmath.Point3f;
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import javax.vecmath.Matrix3d;
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/**
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* Used to calculate the planet positions using kepler equation.<br>
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* This part is left as a exercise for the diploma work, at the end of
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* October 2000. We use the simpler ellipse equation method instead.
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* For example:
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* <pre>
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* use :
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* KeplerEquation keplereq = new KeplerEquation();
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* Point3f [] positions = keplereq.getPositions(CelestialObjectInfo,time);
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* </pre>
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*
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* @author Marcel Portner & Bernhard Hari
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* @version $Revision: 1.10 $
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* @see sss3d.calculations.ellipseequation.EllipseEquation
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*/
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public class KeplerEquation extends OrbitCalculator {
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private CelestialObjectInfo objInfo;
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private double jDay;
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private boolean compressed;
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private boolean kepler;
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private int nbrOfPoints;
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private Point3f[] positions;
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/**
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* Returns the positions of the given planet.
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* The algorithm used is the kepler equation.
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*
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* @param objInfo Information about the planet.
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* @param jDay calculates positions corresponding to the given julian day
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* @param compressed true if the universe is logorithmic compressed or false if
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* it has the real proportion.
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* @return Point3f[] an array of vectors containing the positions.
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*/
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public Point3f[] getPositions(CelestialObjectInfo objInfo, double jDay, boolean compressed) {
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this.objInfo = objInfo;
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// modifiziertes julianisches Datum
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this.jDay = jDay - 2400000.5;
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this.compressed = compressed;
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kepler = false;
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// last is used to mark the end of the array.
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nbrOfPoints = objInfo.getNbrOfPositions();
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positions = new Point3f[nbrOfPoints];
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String type = objInfo.getType();
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if(type.equals(SSS3dConstants.TYPES[SSS3dConstants.PLANET_TYPE])) {
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int planetNr = -1;
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String name = objInfo.getName();
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if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.MERCURY])) {
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planetNr = SSS3dConstants.MERCURY;
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} else if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.VENUS])) {
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planetNr = SSS3dConstants.VENUS;
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} else if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.EARTH])) {
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planetNr = SSS3dConstants.EARTH;
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} else if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.MARS])) {
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planetNr = SSS3dConstants.MARS;
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} else if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.JUPITER])) {
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planetNr = SSS3dConstants.JUPITER;
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} else if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.SATURN])) {
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planetNr = SSS3dConstants.SATURN;
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} else if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.URANUS])) {
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planetNr = SSS3dConstants.URANUS;
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} else if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.NEPTUNE])) {
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planetNr = SSS3dConstants.NEPTUNE;
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} else if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.PLUTO])) {
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planetNr = SSS3dConstants.PLUTO;
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} else {
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System.out.println("Error in KeplerEquation: planet not knowned");
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return null;
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}
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calcPlanetPos(planetNr);
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} else if(type.equals(SSS3dConstants.TYPES[SSS3dConstants.MOON_TYPE])) {
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String name = objInfo.getName();
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if(name.equals(SSS3dConstants.CELESTIAL[SSS3dConstants.MOON])) {
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calcOurMoonPos();
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} else {
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calcMoonPos();
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}
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} else if(type.equals(SSS3dConstants.TYPES[SSS3dConstants.COMET_TYPE])) {
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calcCometPos();
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} else {
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System.out.println("Error in KeplerEquation: Other not supported yet");
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return null;
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}
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return positions;
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}
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/**
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* Returns an array of positons for the given positions, based
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* on the given jDay.<br>
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*
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* @param objPos actual positions of the object.
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* @param jDay calculates positions corresponding to the given julian day
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* @param compressed true if the universe is logorithmic compressed or false if
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* it has the real proportion.
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* @return Point3f[] an array of vectors containing the points
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*/
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public Point3f[] updatePositions(Point3f[] objPos, double jDay, boolean compressed) {
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return objPos;
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}
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/**
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* Calculate the positions of the given planet as kepler ellipse.
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*
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* @param planetNr the planet number for the identification.
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*/
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private void calcPlanetPos(int planetNr) {
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double step = objInfo.getOrbitPeriod() /
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(double)nbrOfPoints * AstronomicalConstants.DAYS;
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Planets planet = new Planets();
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PrecNut prec = new PrecNut();
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for(int i = 0; i < nbrOfPoints; i++) {
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double time = ((double)i * step + jDay -
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AstronomicalConstants.MJD_J2000) / 36525.0;
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Vec3D planpos;
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if(kepler) {
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planpos = planet.kepPosition(planetNr, time);
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} else {
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planpos = planet.pertPosition(planetNr, time);
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}
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// logarithmic or scalar !!!
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if(compressed) {
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planpos.scaleDistance(compressed, 5.0);
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} else {
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planpos.scaleDistance(compressed, AstronomicalConstants.AU / SSS3dConstants.SCALE);
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}
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// Praezession und aequatoriale Koordinaten
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Matrix3d p = prec.precMatrix_Ecl(time, AstronomicalConstants.T_J2000);
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planpos.mul(p);
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positions[i] = new Point3f((float) planpos.x,
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(float) planpos.z,
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(float)-planpos.y);
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}
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}
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/**
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* Calculate the positions of our moon.
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*/
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private void calcOurMoonPos() {
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double step = objInfo.getOrbitPeriod() / (double)nbrOfPoints;
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Moon moon = new Moon();
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for(int i = 0; i < nbrOfPoints; i++) {
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double time = ((double)i * step + jDay -
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AstronomicalConstants.MJD_J2000) / 36525.0;
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Vec3D moonpos = moon.moonEqu(time);
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// logarithmic or scalar !!!
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if(compressed) {
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moonpos.scaleDistance(compressed, 3e-6);
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} else {
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moonpos.scaleDistance(compressed, 1 / SSS3dConstants.SCALE);
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}
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positions[i] = new Point3f((float) moonpos.x,
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(float) moonpos.z,
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(float)-moonpos.y);
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}
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}
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/**
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* Calculate the positions of any moon as a circle.
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*/
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private void calcMoonPos() {
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double x, y, z, phi, r;
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if(compressed) {
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r = StrictMath.log(objInfo.getDistance() / 1000) / 5;
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} else {
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r = objInfo.getDistance() / SSS3dConstants.SCALE;
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}
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double theta = StrictMath.toRadians(objInfo.getOrbitInclinationToEcliptic());
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for(int i = 0; i < nbrOfPoints; i++) {
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phi = ((double)i / nbrOfPoints) * MoreMath.PI2;
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x = r * StrictMath.cos(phi);
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z = -r * StrictMath.sin(phi);
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y = -x * StrictMath.tan(theta);
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positions[i] = new Point3f((float)x, (float)y, (float)z);
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}
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}
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/**
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* Calculate the positions of any comet as kepler ellipse.
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*/
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private void calcCometPos() {
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double step = objInfo.getOrbitPeriod() /
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(double)nbrOfPoints * AstronomicalConstants.DAYS;
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Kepler kepler = new Kepler();
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PrecNut prec = new PrecNut();
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Matrix3d pqr = kepler.gaussVec(MoreMath.RAD * objInfo.getLongitudeNode(),
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MoreMath.RAD * objInfo.getOrbitInclinationToEcliptic(),
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MoreMath.RAD * objInfo.getPerihelion());
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pqr.mul(prec.precMatrix_Ecl((objInfo.getEquinox() - 2000.0) / 100.0,
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(2000.0 - 2000.0) / 100.0));
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for(int i = 0; i < nbrOfPoints; i++) {
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double time = (double)i * step + jDay;
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Vec3D[] vec = kepler.kepler(AstronomicalConstants.GM_SUN,
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objInfo.getEpoch(),
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time,
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objInfo.getDistance(),
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objInfo.getOrbitEccentricity(),
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pqr);
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// logarithmic or scalar !!!
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if(compressed) {
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vec[0].scaleDistance(compressed, 5.0);
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} else {
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vec[0].scaleDistance(compressed, AstronomicalConstants.AU / SSS3dConstants.SCALE);
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}
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positions[i] = new Point3f((float) vec[0].x,
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(float) vec[0].z,
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(float)-vec[0].y);
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}
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}
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}
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