atmosphere.h

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#include "gfx/vec.h"
#include "gfxlib_struct.h"
#include "gfx/matrix.h"
#include "gfx/mesh.h"
#include <vector>

class Atmosphere
{
public:
    struct Parameters
    {
        /* High level parameters */
        /* coefficients for capturing scattering effects of the
         *  atmospheric composition/density */
        float    radius;
        /* low angle */
        GFXColor low_color[2];
        /* low angle */
        GFXColor low_ambient_color[2];
        /* high angle */
        GFXColor high_color[2];
        /* high angle */
        GFXColor high_ambient_color[2];
        float    scattering;
        /* "scattering" coefficient, basically
         *                                        how much the low_color spreads around */
    };

private:
    Parameters user_params;

    class SunBox
    {
public: SunBox( Mesh *m ) : sunbox( m ) {}
        ~SunBox();
        Mesh *sunbox;
    };
    void setArray( float*, const GFXColor& );
    void setArray1( float*, const GFXColor& );
/* Internal state information */
    Mesh   *dome;                                        /* entire sky; for texture mapping */
/* 3 rendering passes, to preserve framerate */
    Mesh   *cap;                                         /* mid to zenith */
    Mesh   *stack;                               /* horizon to zenith */
/* box around the sun (single star for now) */
    std::vector< SunBox* >sunboxes;
    Matrix  tmatrix;
    QVector position;
/* lighting contexts for the above 3 */
    int     l0, l1, l2;
    int     divisions;

public: Atmosphere( const Parameters &params );
    ~Atmosphere();
    const Parameters& parameters();
    void SetParameters( const Parameters &params );

/* Update the precomputed mesh to the new parameters. This is
 *  expensive, so let the upper layers decide when to do this
 */

/* ugh, make update just change the lighting state */
    void Update( const QVector &position, const Matrix &tmatrix );
    void Draw();
    static void ProcessDrawQueue();
    void SetMatricesAndDraw( const QVector &position, const Matrix tmatrix );
/* inherit the orientation of
 *                                                                                the transformation matrix  */
    static void DrawAtmospheres();
};