RefractionExtinction.hpp

/*
 * Stellarium
 * Copyright (C) 2010 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.
 *
 * Refraction and extinction computations.
 * Implementation: 2010-03-23 GZ=Georg Zotti, Georg.Zotti@univie.ac.at
 * 2010-12 FC split into 2 classes, implemented Refraction */

#ifndef _REFRACTIONEXTINCTION_HPP_
#define _REFRACTIONEXTINCTION_HPP_
// USABILITY: added 3 more flags/switches in GUI:
// Temperature [C] [influences refraction]
// Pressure [mbar]  [influences refraction]
// extinction Coeff. k=0...(0.01)...1, [if k=0, no ext. effect]
// SUGGESTION: Allow Temperature/Pressure/ex.Coeff./LightPollution set in the landscape files

#include "VecMath.hpp"
#include "StelProjector.hpp"

class Extinction
{
public:
    enum UndergroundExtinctionMode {
        UndergroundExtinctionZero = 0,  
        UndergroundExtinctionMax = 1,   
        UndergroundExtinctionMirror = 2 
    };
    
    Extinction();
    
    void forward(const Vec3d& altAzPos, float* mag) const
    {
        Q_ASSERT(std::fabs(altAzPos.length()-1.f)<0.001f);
        *mag += airmass(altAzPos[2], false) * ext_coeff;
    }
    
    void forward(const Vec3f& altAzPos, float* mag) const
    {
        Q_ASSERT(std::fabs(altAzPos.length()-1.f)<0.001f);
        *mag += airmass(altAzPos[2], false) * ext_coeff;
    }

    void backward(const Vec3d& altAzPos, float* mag) const
    {
        *mag -= airmass(altAzPos[2], false) * ext_coeff;
    }
    
    void backward(const Vec3f& altAzPos, float* mag) const
    {
        *mag -= airmass(altAzPos[2], false) * ext_coeff;
    }

    void setExtinctionCoefficient(float k) { ext_coeff=k; }
    float getExtinctionCoefficient() const {return ext_coeff;}

    void setUndergroundExtinctionMode(UndergroundExtinctionMode mode) {undergroundExtinctionMode=mode;}
    UndergroundExtinctionMode getUndergroundExtinctionMode() const {return undergroundExtinctionMode;}
    
private:
    float airmass(float cosZ, const bool apparent_z=true) const;

    float ext_coeff;

    UndergroundExtinctionMode undergroundExtinctionMode;
};


class Refraction: public StelProjector::ModelViewTranform
{
public:
    Refraction();

    void forward(Vec3d& altAzPos) const;

    void backward(Vec3d& altAzPos) const;

    void forward(Vec3f& altAzPos) const;

    void backward(Vec3f& altAzPos) const;

    void combine(const Mat4d& m)
    {
        setPreTransfoMat(preTransfoMat*m);
    }

    Mat4d getApproximateLinearTransfo() const {return postTransfoMat*preTransfoMat;}

    StelProjector::ModelViewTranformP clone() const {Refraction* refr = new Refraction(); *refr=*this; return StelProjector::ModelViewTranformP(refr);}

    void setPressure(float p_mbar);
    float getPressure() const {return pressure;}

    void setTemperature(float t_C);
    float getTemperature() const {return temperature;}

    void setPreTransfoMat(const Mat4d& m);
    void setPostTransfoMat(const Mat4d& m);

private:
    void updatePrecomputed();

    void innerRefractionForward(Vec3d& altAzPos) const;
    void innerRefractionBackward(Vec3d& altAzPos) const;
    
    float pressure;
    float temperature;
    float press_temp_corr;

    Mat4d preTransfoMat;
    Mat4d invertPreTransfoMat;
    Mat4f preTransfoMatf;
    Mat4f invertPreTransfoMatf;

    Mat4d postTransfoMat;
    Mat4d invertPostTransfoMat;
    Mat4f postTransfoMatf;
    Mat4f invertPostTransfoMatf;
};

#endif  // _REFRACTIONEXTINCTION_HPP_