//##################################################################################################
//
//   Custom Visualization Core library
//   Copyright (C) 2011-2012 Ceetron AS
//    
//   This library is free software: you can redistribute it and/or modify 
//   it under the terms of the GNU General Public License as published by 
//   the Free Software Foundation, either version 3 of the License, or 
//   (at your option) any later version. 
//    
//   This library is distributed in the hope that it will be useful, but WITHOUT ANY 
//   WARRANTY; without even the implied warranty of MERCHANTABILITY or 
//   FITNESS FOR A PARTICULAR PURPOSE.   
//    
//   See the GNU General Public License at <<http://www.gnu.org/licenses/gpl.html>> 
//   for more details. 
//
//##################################################################################################

#include "cvfScalarMapperContinuousLog.h"

#include "cvfMath.h"
#include "cvfTextureImage.h"
#include <cmath>
#include <limits>

namespace cvf {

//==================================================================================================
///
/// \class cvf::ScalarMapperContinuousLog
/// \ingroup Render
///
/// Maps scalar values to texture coordinates/colors using continuous logarithmic mapping
/// Configured by specifying a number of level colors and a min/max range. 
//==================================================================================================
ScalarMapperContinuousLog::ScalarMapperContinuousLog()
    : m_hasNegativeRange(false),
    m_logRange(0.0),
    m_logRangeMin(0.0)
{
  
}

//--------------------------------------------------------------------------------------------------
/// 
//--------------------------------------------------------------------------------------------------
double ScalarMapperContinuousLog::normalizedValue(double scalarValue) const
{
    if (m_hasNegativeRange) scalarValue = -1.0*scalarValue;

    double logValue;

    if (scalarValue <= 0) logValue = std::numeric_limits<double>::min_exponent10;
    else                  logValue = log10(scalarValue);

   if (m_logRange != 0)
    {
        return cvf::Math::clamp((logValue - m_logRangeMin)/m_logRange, 0.0, 1.0);
    }
    else
    {
        return 0;
    }
} 

//--------------------------------------------------------------------------------------------------
/// 
//--------------------------------------------------------------------------------------------------
double ScalarMapperContinuousLog::domainValue(double normalizedPosition) const
{
    double logValue = normalizedPosition*m_logRange + m_logRangeMin;
    double domainVal = pow(10, logValue);

    if (m_hasNegativeRange)
        domainVal *= -1.0;

    return domainVal;
}

//--------------------------------------------------------------------------------------------------
/// 
//--------------------------------------------------------------------------------------------------
void ScalarMapperContinuousLog::rangeUpdated()
{
    m_hasNegativeRange = false;

    double transformedRangeMax = m_rangeMax;
    double transformedRangeMin = m_rangeMin;

    if ( m_rangeMax <= 0 &&  m_rangeMin <= 0)
    { 
        m_hasNegativeRange = true;

        transformedRangeMax = -1.0*transformedRangeMax;
        transformedRangeMin = -1.0*transformedRangeMin;
    }

    double logRangeMax = (transformedRangeMax > 0) ? log10(transformedRangeMax): std::numeric_limits<double>::min_exponent10;
    m_logRangeMin      = (transformedRangeMin > 0) ? log10(transformedRangeMin): std::numeric_limits<double>::min_exponent10;

    m_logRange = logRangeMax - m_logRangeMin; 
}

} // namespace cvf
