ZodiacalLight.hpp

/*
 * Stellarium
 * Copyright (C) 2002 Fabien Chereau
 * Copyright (C) 2014 Georg Zotti: ZodiacalLight
 * 
 * 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 _ZODIACALLIGHT_
#define _ZODIACALLIGHT_

#include <QVector>
#include "StelModule.hpp"
#include "VecMath.hpp"
#include "StelTextureTypes.hpp"
#include "StelLocation.hpp"

// GZ OCRed and hand-edited the table in Excel, first filling the missing data around the sun with values based on
// Leinert 1975: Zodiacal Light - A Measure of the Interplanetary Environment. Space Science Reviews 18, 281-339.
// From the combined table, I tried to create a texture. Image editing hides the numbers, so I finally exported the
// data (power 0.75) into a 3D surface which I edited in Sketchup: fill the data hole "mountain" with believeable values.
// Export to OBJ, extract and mirror vertices. Then, in ArcGIS10,
// 3D Analyst Toolbox -> From File -> ASCII 3D to Feature Class
// 3D Analyst Toolbox -> Raster Interpolation -> IDW: cell size: 1 (degree), power:2, var.dist., 12points.
// Spatial Analyst Tools -> Math -> Power: 1.3333 (to invert the 0.75 above)
// Spatial Analyst Tools -> Math -> Log2 (to provide better scaling, matches better with visual impression)
// This float32 texture was then exported to a regular 8bit grayscale PNG texture.
// It turned out that the original distribution had a quite boxy appearance around the data hole.
// I had to do more editing, finally also within the data values, but I think much of the error is in these published data values.
// The true values would massively concentrate further around the sun, but a single 8bit texture cannot deliver more dynamic range in brightness.
// The current solution matches my own observations in a very dark location in Namibia, May 2014, and photos taken in Libya in March 2006.

class ZodiacalLight : public StelModule
{
    Q_OBJECT
    Q_PROPERTY(bool flagZodiacalLightDisplayed
           READ getFlagShow
           WRITE setFlagShow
           NOTIFY zodiacalLightDisplayedChanged)
    Q_PROPERTY(double intensity
           READ getIntensity
           WRITE setIntensity
           NOTIFY intensityChanged)
    Q_PROPERTY(Vec3f color
           READ getColor
           WRITE setColor
           NOTIFY colorChanged)

public:
    ZodiacalLight();
    virtual ~ZodiacalLight();
    
    // Methods defined in the StelModule class
    virtual void init();

    virtual void draw(StelCore* core);
    
    virtual void update(double deltaTime);
    
    virtual double getCallOrder(StelModuleActionName actionName) const;
    
    // Setter and getters
public slots:
    double getIntensity() const {return intensity;}
    void setIntensity(double aintensity) {if(aintensity!=intensity){intensity = aintensity; emit intensityChanged(intensity);}}
    
    Vec3f getColor() const {return color;}
    void setColor(const Vec3f& c) {if (c!=color) { color=c; emit colorChanged(c);}}
    
    void setFlagShow(bool b);
    bool getFlagShow(void) const;

private slots:
    void handleLocationChanged(StelLocation loc);

signals:
    void zodiacalLightDisplayedChanged(const bool displayed);
    void intensityChanged(double intensity);
    void colorChanged(Vec3f color);
    
private:
    StelTextureSP tex;
    Vec3f color; // global color
    double intensity;
    float intensityFovScale; // like for constellations: reduce brightness when zooming in.
    float intensityMinFov;
    float intensityMaxFov;
    class LinearFader* fader;
    double lastJD; // keep date of last computation. Position will be updated only if far enough away from last computation.

    struct StelVertexArray* vertexArray;
    QVector<Vec3d> eclipticalVertices;
};

#endif // _ZODIACALLIGHT_HPP_