Skybright.hpp

 /*
 * Copyright (C) 2003 Fabien Chereau
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA  02110-1335, USA.
 */

#ifndef _SKYBRIGHT_HPP_
#define _SKYBRIGHT_HPP_

// GZ: tentative additions to the documentation.
class Skybright
{
public:
    Skybright();

    void setDate(const int year, const int month, const float moonPhase);

    void setLocation(const float latitude, const float altitude, const float temperature=15.f, const float relativeHumidity=40.f);

    void setSunMoon(const float cosDistMoonZenith, const float cosDistSunZenith);

    float getLuminance(float cosDistMoon, const float cosDistSun, const float cosDistZenith) const;

private:
    float airMassMoon;  // Air mass for the Moon
    float airMassSun;   // Air mass for the Sun
    float magMoon;      // Moon magnitude
    float RA;           // Extremely crude estimate of Right Ascension of the Sun!
    float K;            // Summary extinction coefficient
    float C3;           // Term for moon brightness computation
    float C4;           // Term for sky brightness computation
    float SN;           // Snellen Ratio (20/20=1.0, good 20/10=2.0)

    // Optimisation variables
    float bNightTerm;
    float bMoonTerm1;
    float bTwilightTerm;
};

#endif // _SKYBRIGHT_HPP_