215 lines
6.1 KiB
C++
215 lines
6.1 KiB
C++
// astro.h
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//
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// Copyright (C) 2001-2006 Chris Laurel <claurel@shatters.net>
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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#ifndef _CELENGINE_ASTRO_H_
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#define _CELENGINE_ASTRO_H_
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#include <iostream>
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#include <string>
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#include <cmath>
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#include <celmath/vecmath.h>
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#include <celengine/univcoord.h>
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#ifndef TARGET_OS_MAC
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#ifdef __GNUC__
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#include <iconv.h>
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#endif
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#endif
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#define SOLAR_ABSMAG 4.83f
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#define LN_MAG 1.085736
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#define LY_PER_PARSEC 3.26167
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#define KM_PER_LY 9460730472580.8
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// Old incorrect value; will be required for cel:// URL compatibility
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// #define OLD_KM_PER_LY 9466411842000.000
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#define KM_PER_AU 149597870.7
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#define AU_PER_LY (KM_PER_LY / KM_PER_AU)
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namespace astro
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{
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class Date
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{
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public:
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Date();
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Date(int Y, int M, int D);
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Date(double);
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enum Format
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{
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Locale = 0,
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TZName = 1,
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UTCOffset = 2,
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};
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const char* toCStr(Format format = Locale) const;
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operator double() const;
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public:
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int year;
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int month;
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int day;
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int hour;
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int minute;
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int wday; // week day, 0 Sunday to 6 Saturday
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int utc_offset; // offset from utc in seconds
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std::string tzname; // timezone name
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double seconds;
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#ifndef TARGET_OS_MAC
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#ifdef __GNUC__
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private:
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// Static members used to store locale related UTF-8 information
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static bool utf8Locale;
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static bool utf8LocaleSet;
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static iconv_t utf8Iconv;
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#endif
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#endif
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};
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bool parseDate(const std::string&, Date&);
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enum CoordinateSystem
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{
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Universal = 0,
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Ecliptical = 1,
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Equatorial = 2,
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Geographic = 3,
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ObserverLocal = 4,
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PhaseLock = 5,
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Chase = 6,
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};
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// Time scale conversions
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// UTC - Coordinated Universal Time
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// TAI - International Atomic Time
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// TT - Terrestrial Time
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// TCB - Barycentric Coordinate Time
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// TDB - Barycentric Dynamical Time
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inline double secsToDays(double s)
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{
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return s * (1.0 / 86400.0);
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}
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inline double daysToSecs(double d)
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{
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return d * 86400.0;
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}
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// Convert to and from UTC dates
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double UTCtoTAI(const astro::Date& utc);
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astro::Date TAItoUTC(double tai);
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double UTCtoTDB(const astro::Date& utc);
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astro::Date TDBtoUTC(double tdb);
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astro::Date TDBtoLocal(double tdb);
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// Convert among uniform time scales
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double TTtoTAI(double tt);
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double TAItoTT(double tai);
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double TTtoTDB(double tt);
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double TDBtoTT(double tdb);
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// Conversions to and from Julian Date UTC--other time systems
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// should be preferred, since UTC Julian Dates aren't defined
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// during leapseconds.
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double JDUTCtoTAI(double utc);
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double TAItoJDUTC(double tai);
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// Magnitude conversions
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float lumToAbsMag(float lum);
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float lumToAppMag(float lum, float lyrs);
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float absMagToLum(float mag);
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float appMagToLum(float mag, float lyrs);
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template<class T> T absToAppMag(T absMag, T lyrs)
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{
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return (T) (absMag - 5 + 5 * log10(lyrs / LY_PER_PARSEC));
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}
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template<class T> T appToAbsMag(T appMag, T lyrs)
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{
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return (T) (appMag + 5 - 5 * log10(lyrs / LY_PER_PARSEC));
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}
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// Distance conversions
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float lightYearsToParsecs(float);
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double lightYearsToParsecs(double);
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float parsecsToLightYears(float);
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double parsecsToLightYears(double);
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float lightYearsToKilometers(float);
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double lightYearsToKilometers(double);
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float kilometersToLightYears(float);
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double kilometersToLightYears(double);
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float lightYearsToAU(float);
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double lightYearsToAU(double);
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// TODO: templatize the rest of the conversion functions
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template<class T> T AUtoLightYears(T au)
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{
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return au / (T) AU_PER_LY;
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}
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float AUtoKilometers(float);
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double AUtoKilometers(double);
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float kilometersToAU(float);
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double kilometersToAU(double);
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float microLightYearsToKilometers(float);
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double microLightYearsToKilometers(double);
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float kilometersToMicroLightYears(float);
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double kilometersToMicroLightYears(double);
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float microLightYearsToAU(float);
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double microLightYearsToAU(double);
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float AUtoMicroLightYears(float);
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double AUtoMicroLightYears(double);
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double secondsToJulianDate(double);
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double julianDateToSeconds(double);
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void decimalToDegMinSec(double angle, int& degrees, int& minutes, double& seconds);
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double degMinSecToDecimal(int degrees, int minutes, double seconds);
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void decimalToHourMinSec(double angle, int& hours, int& minutes, double& seconds);
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float sphereIlluminationFraction(Point3d spherePos,
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Point3d viewerPos);
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Point3d heliocentricPosition(const UniversalCoord& universal,
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const Point3f& starPosition);
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UniversalCoord universalPosition(const Point3d& heliocentric,
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const Point3f& starPosition);
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UniversalCoord universalPosition(const Point3d& heliocentric,
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const UniversalCoord& starPosition);
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Point3f equatorialToCelestialCart(float ra, float dec, float distance);
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Point3d equatorialToCelestialCart(double ra, double dec, double distance);
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void anomaly(double meanAnomaly, double eccentricity,
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double& trueAnomaly, double& eccentricAnomaly);
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double meanEclipticObliquity(double jd);
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extern const double J2000;
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extern const double speedOfLight; // km/s
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extern const double G; // gravitational constant
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extern const double SolarMass;
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extern const double EarthMass;
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extern const double LunarMass;
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extern const double J2000Obliquity;
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};
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// Convert a date structure to a Julian date
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std::ostream& operator<<(std::ostream& s, const astro::Date);
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#endif // _CELENGINE_ASTRO_H_
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