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ImathColorAlgo.cpp

///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
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// *       Redistributions in binary form must reproduce the above
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// distribution.
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// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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///////////////////////////////////////////////////////////////////////////


//----------------------------------------------------------------------------
//
//    Implementation of non-template items declared in ImathColorAlgo.h
//
//----------------------------------------------------------------------------

#include <ImathColorAlgo.h>

namespace Imath {


Vec3<double>
hsv2rgb_d(const Vec3<double> &hsv)
{
    double hue = hsv.x;
    double sat = hsv.y;
    double val = hsv.z;

    double x = 0.0, y = 0.0, z = 0.0;
    
    if (hue == 1) hue = 0;
    else hue *= 6;

    int i = int(Math<double>::floor(hue));
    double f = hue-i;
    double p = val*(1-sat);
    double q = val*(1-(sat*f));
    double t = val*(1-(sat*(1-f)));

    switch (i) 
    {
      case 0: x = val; y = t; z = p; break;
      case 1: x = q; y = val; z = p; break;
      case 2: x = p; y = val; z = t; break;
      case 3: x = p; y = q; z = val; break;
      case 4: x = t; y = p; z = val; break;
      case 5: x = val; y = p; z = q; break;
    }

    return Vec3<double>(x,y,z);
}


Color4<double>    
hsv2rgb_d(const Color4<double> &hsv)
{
    double hue = hsv.r;
    double sat = hsv.g;
    double val = hsv.b;

    double   r = 0.0, g = 0.0, b = 0.0;
    
    if (hue == 1) hue = 0;
    else hue *= 6;

    int i = int(Math<double>::floor(hue));
    double f = hue-i;
    double p = val*(1-sat);
    double q = val*(1-(sat*f));
    double t = val*(1-(sat*(1-f)));

    switch (i) 
    {
      case 0: r = val; g = t; b = p; break;
      case 1: r = q; g = val; b = p; break;
      case 2: r = p; g = val; b = t; break;
      case 3: r = p; g = q; b = val; break;
      case 4: r = t; g = p; b = val; break;
      case 5: r = val; g = p; b = q; break;
    }

    return Color4<double>(r,g,b,hsv.a);
}



Vec3<double>
rgb2hsv_d(const Vec3<double> &c)
{
    const double &x = c.x;
    const double &y = c.y;
    const double &z = c.z;

    double max     = (x > y) ? ((x > z) ? x : z) : ((y > z) ? y : z);
    double min     = (x < y) ? ((x < z) ? x : z) : ((y < z) ? y : z);
    double range = max - min;
    double val     = max;
    double sat   = 0;
    double hue   = 0;
    
    if (max != 0)   sat = range/max;
    
    if (sat != 0) 
    {
      double h;
      
      if      (x == max)      h =     (y - z) / range;
      else if (y == max)      h = 2 + (z - x) / range;
      else        h = 4 + (x - y) / range;

      hue = h/6.;
          
      if (hue < 0.)
          hue += 1.0;
    }
    return Vec3<double>(hue,sat,val);
}


Color4<double>
rgb2hsv_d(const Color4<double> &c)
{
    const double &r = c.r;
    const double &g = c.g;
    const double &b = c.b;

    double max     = (r > g) ? ((r > b) ? r : b) : ((g > b) ? g : b);
    double min     = (r < g) ? ((r < b) ? r : b) : ((g < b) ? g : b);
    double range = max - min;
    double val     = max;
    double sat   = 0;
    double hue   = 0;
    
    if (max != 0)   sat = range/max;
    
    if (sat != 0) 
    {
      double h;
      
      if      (r == max)      h =     (g - b) / range;
      else if (g == max)      h = 2 + (b - r) / range;
      else        h = 4 + (r - g) / range;

      hue = h/6.;
          
      if (hue < 0.)
          hue += 1.0;
    }
    return Color4<double>(hue,sat,val,c.a);
}


} // namespace Imath

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