Celestin Apprentice 5/Apprentice-Release5.iso/Source Code/Libraries/Dots & Pixels/headers/flowsettings.h

C/C++ Source or Header | 1995-09-29 | 5KB | 190 lines

#pragma once
//
// flowsettings: a simple way to read and write flow parameters
//
class flowsettings
{
    public:
        double translation_x;
        double translation_y;
        double expansion;
        double rotation;            // in degrees per second
        double shear_magnitude;
        double shear_direction;        // in degrees

        flowsettings();
        void init();

        int is_translation_free() const;
        int is_rotation_free() const;
        int is_expansion_free() const;
        int is_shear_free() const;
        int is_unity() const;

        int operator==( const flowsettings &that) const;

    friend ostream& operator<<( ostream& destroom,
                                const flowsettings &thesettings);

    friend istream& operator>>( istream& destroom, flowsettings &thesettings);
};
//
// flowexpsettings effectively contains three settings; the first is the
// reference flow, the second and third contain the starting and ending point
// of the 'trajectory' alongside which testing takes place.
// Note that usually, point_zero will equal the reference flow. We allow
// these to differ because we migth wish to ask for instance:
// 'which one rotates faster', where the reference flow is rotating and
// expanding, whereas the test flows are only rotating.
// The 'distance' between 'point_zero' and 'point_one' determines the 'unit'.
//
class flowexpsettings : public flowsettings
{
    public:
        flowsettings point_zero;
        flowsettings point_one;

        flowexpsettings();

        void getvalue( flowsettings *new_value, const double lambda);
        //
        // the ..._does_change members return true whenever the relevant
        // parts of point_zero and/or point_one differ.
        //
        int dx_does_change() const;
        int dy_does_change() const;
        int translation_does_change() const;
        int exp_does_change() const;
        int rot_does_change() const;
        int mag_does_change() const;
        int dir_does_change() const;
        int shear_does_change() const;

    friend ostream& operator<<( ostream& destroom,
                        const flowexpsettings &thesettings);

    friend istream& operator>>( istream& destroom,
                        flowexpsettings &thesettings);
    //
    // The advantage of 'shorthand_out' and 'longhand_out' over
    // "ostream &operator>>" is that they are better suited for import of the
    // data into a spreadsheet.
    //
    // Use 'shorthand_out' to write the settings in a non-recoverable format
    // 'shorthand_out' can be a convenient format for importing into a
    // spreadsheet, but the number of columns produced by 'shorthand_out'
    // varies with the number of varying parameters in the flowexpsettings.
    //
    // 'longhand_out' is a similar format, but with a fixed number of columns.
    //
    // If I knew how to do it, I would possibly implement this with an IOStream
    // manipulator.
    //
    // The flag 'force_three' is used to indicate that 'point_zero' should
    // also be output when it is equal to the reference flow.
    //
    void shorthand_out( ostream &destroom = cout, int force_three = false) const;
    void longhand_out( ostream &destroom = cout, int force_three = false) const;

    private:
        static double lin_interpolate( double start, double end, double lambda);
        static double log_interpolate( double start, double end, double lambda);
};

inline void flowsettings::init()
{
    translation_x   = 0.0;
    translation_y   = 0.0;
    expansion       = 1.0;
    rotation        = 0.0;
    shear_magnitude = 1.0;
    shear_direction = 0.0;
}

inline flowsettings::flowsettings()
{
    init();
}

inline int flowsettings::is_translation_free() const
{
    return ((translation_x == 0.0) && (translation_y == 0.0));
}

inline int flowsettings::is_rotation_free() const
{
    return (rotation == 0.0);
}

inline int flowsettings::is_expansion_free() const
{
    return (expansion == 1.0);
}

inline int flowsettings::is_shear_free() const
{
    return (shear_magnitude == 1.0);
}

inline int flowsettings::is_unity() const
{
    return ( is_translation_free() &&
        is_expansion_free() && is_rotation_free() &&
        is_shear_free() && (shear_direction == 0.0)
    );
}

inline flowexpsettings::flowexpsettings() : flowsettings()
{
    point_zero.init();
    point_one.init();
}

inline double flowexpsettings::lin_interpolate(
            double start, double end, double lambda)
{
    return (1.0 - lambda) * start + lambda * end;
}

inline double flowexpsettings::log_interpolate(
            double start, double end, double lambda)
{
    return exp( (1.0 - lambda) * log( start) + lambda * log( end));
}

inline int flowexpsettings::dx_does_change() const
{
    return ((translation_x != point_one.translation_x)
                || (translation_x != point_zero.translation_x));
}

inline int flowexpsettings::dy_does_change() const
{
    return ((translation_y != point_one.translation_y)
                || (translation_y != point_zero.translation_y));
}

inline int flowexpsettings::exp_does_change() const
{
    return ((expansion != point_one.expansion)
                || (expansion != point_zero.expansion));
}

inline int flowexpsettings::rot_does_change() const
{
    return ((rotation != point_one.rotation)
                || (rotation != point_zero.rotation));
}

inline int flowexpsettings::mag_does_change() const
{
    return ((shear_magnitude != point_one.shear_magnitude)
                || (shear_magnitude != point_zero.shear_magnitude));
}

inline int flowexpsettings::dir_does_change() const
{
    return ((shear_direction != point_one.shear_direction)
                || (shear_direction != point_zero.shear_direction));
}