TetraInterpolator.cpp

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#include "TetraInterpolator.hpp"
#include "Color.hpp"
#include "AbstractLut.hpp"

#include <cmath>

namespace tuttle {

template<class T>
T clamp( const T v, const T min, const T max )
{
    return std::max(min, std::min( v, max) );
}

Color TetraInterpolator::interpolate( const AbstractLut* lut, const double x, const double y, const double z ) const
{
        const std::size_t dimSize = lut->dimSize();

        const double xc = clamp( x, 0.0, 1.0 );
        const double yc = clamp( y, 0.0, 1.0 );
        const double zc = clamp( z, 0.0, 1.0 );
        const unsigned int x0 = (unsigned int)std::floor( xc * ( dimSize - 1 ) );
        const unsigned int y0 = (unsigned int)std::floor( yc * ( dimSize - 1 ) );
        const unsigned int z0 = (unsigned int)std::floor( zc * ( dimSize - 1 ) );

        // par defaut le pas de la grille est de 1
        const unsigned int x1 = x0 + 1;
        const unsigned int y1 = y0 + 1;
        const unsigned int z1 = z0 + 1;

        const Color p000 = lut->getIndexedColor( x0, y0, z0 );
        const Color p001 = lut->getIndexedColor( x0, y0, z1 );
        const Color p010 = lut->getIndexedColor( x0, y1, z0 );
        const Color p011 = lut->getIndexedColor( x0, y1, z1 );
        const Color p100 = lut->getIndexedColor( x1, y0, z0 );
        const Color p101 = lut->getIndexedColor( x1, y0, z1 );
        const Color p110 = lut->getIndexedColor( x1, y1, z0 );
        const Color p111 = lut->getIndexedColor( x1, y1, z1 );

        const double dx = x * ( dimSize - 1.0 ) - (double)x0;
        const double dy = y * ( dimSize - 1.0 ) - (double)y0;
        const double dz = z * ( dimSize - 1.0 ) - (double)z0;

        const Color c0 = p000;

        Color c1, c2, c3;
        if( dx >= dy && dy >= dz )     // T1
        {
                c1 = ( p100 - p000 ); c2 = ( p110 - p100 ); c3 = ( p111 - p110 );
        }
        else if( dx >= dz && dz >= dy ) // T2
        {
                c1 = ( p100 - p000 ); c2 = ( p111 - p101 ); c3 = ( p101 - p100 );
        }
        else if( dz >= dx && dx >= dy ) // T3
        {
                c1 = ( p101 - p001 ); c2 = ( p111 - p101 ); c3 = ( p001 - p000 );
        }
        else if( dy >= dx && dx >= dz ) // T4
        {
                c1 = ( p110 - p010 ); c2 = ( p010 - p000 ); c3 = ( p111 - p110 );
        }
        else if( dy >= dz && dz >= dx ) // T5
        {
                c1 = ( p111 - p011 ); c2 = ( p010 - p000 ); c3 = ( p011 - p010 );
        }
        else if( dz >= dy && dy >= dx ) // T6
        {
                c1 = ( p111 - p011 ); c2 = ( p011 - p001 ); c3 = ( p001 - p000 );
        }
        c1 *= dx; c2 *= dy; c3 *= dz;

        return Color( c0.x + c1.x + c2.x + c3.x,
                      c0.y + c1.y + c2.y + c3.y,
                      c0.z + c1.z + c2.z + c3.z );
}

};