source: NonGTP/OpenEXR/include/Imath/ImathColorAlgo.h @ 855

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//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
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#ifndef INCLUDED_IMATHCOLORALGO_H
#define INCLUDED_IMATHCOLORALGO_H


#include <ImathColor.h>
#include <ImathMath.h>
#include <ImathLimits.h>

namespace Imath {


//
//      Non-templated helper routines for color conversion.
//      These routines eliminate type warnings under g++.
//

Vec3<double>    hsv2rgb_d(const Vec3<double> &hsv);

Color4<double>  hsv2rgb_d(const Color4<double> &hsv);


Vec3<double>    rgb2hsv_d(const Vec3<double> &rgb);

Color4<double>  rgb2hsv_d(const Color4<double> &rgb);


//
//      Color conversion functions and general color algorithms
//
//      hsv2rgb(), rgb2hsv(), rgb2packed(), packed2rgb()
//      see each funtion definition for details.
//

template<class T> 
Vec3<T>  
hsv2rgb(const Vec3<T> &hsv)
{
    if ( limits<T>::isIntegral() )
    {
        Vec3<double> v = Vec3<double>(hsv.x / double(limits<T>::max()),
                                      hsv.y / double(limits<T>::max()),
                                      hsv.z / double(limits<T>::max()));
        Vec3<double> c = hsv2rgb_d(v);
        return Vec3<T>((T) (c.x * limits<T>::max()),
                       (T) (c.y * limits<T>::max()),
                       (T) (c.z * limits<T>::max()));
    }
    else
    {
        Vec3<double> v = Vec3<double>(hsv.x, hsv.y, hsv.z);
        Vec3<double> c = hsv2rgb_d(v);
        return Vec3<T>((T) c.x, (T) c.y, (T) c.z);
    }
}


template<class T> 
Color4<T>  
hsv2rgb(const Color4<T> &hsv)
{
    if ( limits<T>::isIntegral() )
    {
        Color4<double> v = Color4<double>(hsv.r / float(limits<T>::max()),
                                          hsv.g / float(limits<T>::max()),
                                          hsv.b / float(limits<T>::max()),
                                          hsv.a / float(limits<T>::max()));
        Color4<double> c = hsv2rgb_d(v);
        return Color4<T>((T) (c.r * limits<T>::max()),
                         (T) (c.g * limits<T>::max()),
                         (T) (c.b * limits<T>::max()),
                         (T) (c.a * limits<T>::max()));
    }
    else
    {
        Color4<double> v = Color4<double>(hsv.r, hsv.g, hsv.g, hsv.a);
        Color4<double> c = hsv2rgb_d(v);
        return Color4<T>((T) c.r, (T) c.g, (T) c.b, (T) c.a);
    }
}


template<class T> 
Vec3<T>  
rgb2hsv(const Vec3<T> &rgb)
{
    if ( limits<T>::isIntegral() )
    {
        Vec3<double> v = Vec3<double>(rgb.x / double(limits<T>::max()),
                                      rgb.y / double(limits<T>::max()),
                                      rgb.z / double(limits<T>::max()));
        Vec3<double> c = rgb2hsv_d(v);
        return Vec3<T>((T) (c.x * limits<T>::max()),
                       (T) (c.y * limits<T>::max()),
                       (T) (c.z * limits<T>::max()));
    }
    else
    {
        Vec3<double> v = Vec3<double>(rgb.x, rgb.y, rgb.z);
        Vec3<double> c = rgb2hsv_d(v);
        return Vec3<T>((T) c.x, (T) c.y, (T) c.z);
    }
}


template<class T> 
Color4<T>  
rgb2hsv(const Color4<T> &rgb)
{
    if ( limits<T>::isIntegral() )
    {
        Color4<double> v = Color4<double>(rgb.r / float(limits<T>::max()),
                                          rgb.g / float(limits<T>::max()),
                                          rgb.b / float(limits<T>::max()),
                                          rgb.a / float(limits<T>::max()));
        Color4<double> c = rgb2hsv_d(v);
        return Color4<T>((T) (c.r * limits<T>::max()),
                         (T) (c.g * limits<T>::max()),
                         (T) (c.b * limits<T>::max()),
                         (T) (c.a * limits<T>::max()));
    }
    else
    {
        Color4<double> v = Color4<double>(rgb.r, rgb.g, rgb.g, rgb.a);
        Color4<double> c = rgb2hsv_d(v);
        return Color4<T>((T) c.r, (T) c.g, (T) c.b, (T) c.a);
    }
}

template <class T>
PackedColor
rgb2packed(const Vec3<T> &c)
{
    if ( limits<T>::isIntegral() )
    {
        float x = c.x / float(limits<T>::max());
        float y = c.y / float(limits<T>::max());
        float z = c.z / float(limits<T>::max());
        return rgb2packed( V3f(x,y,z) );
    }
    else
    {
        return (  (PackedColor) (c.x * 255)             |
                (((PackedColor) (c.y * 255)) << 8)      |
                (((PackedColor) (c.z * 255)) << 16)     | 0xFF000000 );
    }
}

template <class T>
PackedColor
rgb2packed(const Color4<T> &c)
{
    if ( limits<T>::isIntegral() )
    {
        float r = c.r / float(limits<T>::max());
        float g = c.g / float(limits<T>::max());
        float b = c.b / float(limits<T>::max());
        float a = c.a / float(limits<T>::max());
        return rgb2packed( C4f(r,g,b,a) );
    }
    else
    {
        return (  (PackedColor) (c.r * 255)             |
                (((PackedColor) (c.g * 255)) << 8)      |
                (((PackedColor) (c.b * 255)) << 16)     |
                (((PackedColor) (c.a * 255)) << 24));
    }
}

//
//      This guy can't return the result because the template
//      parameter would not be in the function signiture. So instead,
//      its passed in as an argument.
//

template <class T>
void
packed2rgb(PackedColor packed, Vec3<T> &out)
{
    if ( limits<T>::isIntegral() )
    {
        T f = limits<T>::max() / ((PackedColor)0xFF);
        out.x =  (packed &     0xFF) * f;
        out.y = ((packed &   0xFF00) >>  8) * f;
        out.z = ((packed & 0xFF0000) >> 16) * f;
    }
    else
    {
        T f = T(1) / T(255);
        out.x =  (packed &     0xFF) * f;
        out.y = ((packed &   0xFF00) >>  8) * f;
        out.z = ((packed & 0xFF0000) >> 16) * f;
    }
}

template <class T>
void
packed2rgb(PackedColor packed, Color4<T> &out)
{
    if ( limits<T>::isIntegral() )
    {
        T f = limits<T>::max() / ((PackedColor)0xFF);
        out.r =  (packed &       0xFF) * f;
        out.g = ((packed &     0xFF00) >>  8) * f;
        out.b = ((packed &   0xFF0000) >> 16) * f;
        out.a = ((packed & 0xFF000000) >> 24) * f;
    }
    else
    {
        T f = T(1) / T(255);
        out.r =  (packed &       0xFF) * f;
        out.g = ((packed &     0xFF00) >>  8) * f;
        out.b = ((packed &   0xFF0000) >> 16) * f;
        out.a = ((packed & 0xFF000000) >> 24) * f;
    }
}


} // namespace Imath

#endif