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Spectrum.h

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/*
    File:       Spectrum.h

    Function:   Provides classes for manipulating spectra

    Author:     Andrew Willmott

    Copyright:  (c) 1999-2000, Andrew Willmott
*/

#ifndef __Spectrum__
#define __Spectrum__

#include "Geometry.h"
#include "Image.h"

class Spectrum : public Vecf
{
public:
    
                Spectrum() : Vecf(kComponents)
                { MakeZero(); };
                Spectrum(const Vecf &v) : Vecf(v)
                { Assert(Elts() == kComponents, "bad spectrum"); };
                Spectrum(Float k) : Vecf(kComponents)
                { MakeBlock(k); };

    Colour      ToCIE_XYZ();

    static Int  GetNumComponents()
                { return(kComponents); };

    static const Int    kComponents;    // number of (constant) basis functions
    static const Float  kStart;         // start of spectrum
    static const Float  kEnd;           // end of spectrum
};

class SpectralCurve
{
public:
    virtual         ~SpectralCurve();
    
                    operator Spectrum();

    virtual Float   Sample(Float lambda) const = 0;
                    // sample curve at wavelength lambda
    virtual Float   Integral(Float lambda) const;
                    // return integral of curve from 0 to lambda
    virtual Float   MaxCmpt() const;

    Void            MakeImage(Image &image, ClrReal maxAmplitude = -1.0);
                    // Plot the spectrum into image.
    Colour          ToCIE_XYZ();
                    // map the spectrum to the CIE XYZ colour system
};

class RegularSpectralCurve : public SpectralCurve
{
public:
                RegularSpectralCurve(Float *sdata, Int start, Int end, Int divisions);
                ~RegularSpectralCurve();

    Float       Sample(Float lambda) const;
//  Float       Integral(Float lambda) const;

protected:
    Float       *data;
    Float       *accumData;
    Int         waveDivs;
    Float       waveStart, waveEnd, waveDelta;
};

class IrregularSpectralCurve : public SpectralCurve
{
public:
                IrregularSpectralCurve();
                IrregularSpectralCurve(Float *amps, Float *wavs, Int divs);
                ~IrregularSpectralCurve();

    Float       Sample(Float lambda) const;
//  Float       Integral(Float lambda) const;

    IrregularSpectralCurve
                &ReadSDFile(FileName filename);

protected:
    Float       *amplitudes;
    Float       *accumAmplitudes;
    Float       *wavelengths;
    Int         divisions;
};

// --- CIE colour matching functions ------------------------------------

extern RegularSpectralCurve kCIE_xbar;
extern RegularSpectralCurve kCIE_ybar;
extern RegularSpectralCurve kCIE_zbar;

// --- useful utilities --------------------------------------------------

Colour      WavelengthToXYZ(ClrReal lambda);

class ChromaticitySpectrum : public SpectralCurve
{
public:
    ChromaticitySpectrum(ClrReal x, ClrReal y);

    Float       Sample(Float lambda) const;

protected:
    ClrReal     M1, M2;
};

class BlackBodySpectrum : public SpectralCurve
{
public:
    BlackBodySpectrum(Float temperature);

    Float       Sample(Float lambda) const;

protected:
    Float       temp;
};

Void DrawChromaticityImage(Image &image);

#endif

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