TrilinInterpolator.cpp

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#include "TrilinInterpolator.hpp"
#include "Color.hpp"
#include "AbstractLut.hpp"
#include <cmath>

namespace tuttle {

Color TrilinInterpolator::interpolate( const AbstractLut* lut, const double x, const double y, const double z ) const
{
        Color p000, p001, p010, p011, p100, p101, p110, p111;
        unsigned int x0, y0, z0, x1, y1, z1;
        unsigned int x1MinusX0, y1MinusY0, z1MinusZ0;
        double oneByX1MinusX0, oneByY1MinusY0, oneByZ1MinusZ0;
        double dx, dy, dz;
        Color c0, c1, c2, c3, c4, c5, c6, c7;
        Color black( 0., 0., 0. );
        size_t dimSize = lut->dimSize();

        x0 = (unsigned int)std::floor( x * ( dimSize - 1 ) );
        y0 = (unsigned int)std::floor( y * ( dimSize - 1 ) );
        z0 = (unsigned int)std::floor( z * ( dimSize - 1 ) );

        x1 = x0 + 1;
        y1 = y0 + 1;
        z1 = z0 + 1;

        if( x1 >= dimSize )
                x1 = dimSize - 1;
        else if( x1 < 0 )
                x1 = 0;
        if( y1 >= dimSize )
                y1 = dimSize - 1;
        else if( y1 < 0 )
                y1 = 0;
        if( z1 >= dimSize )
                z1 = dimSize - 1;
        else if( z1 < 0 )
                z1 = 0;

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

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

        c0             = p000;
        x1MinusX0      = x1 - x0;
        y1MinusY0      = y1 - y0;
        z1MinusZ0      = z1 - z0;
        oneByX1MinusX0 = 1.0 / (double) x1MinusX0;
        oneByY1MinusY0 = 1.0 / (double) y1MinusY0;
        oneByZ1MinusZ0 = 1.0 / (double) z1MinusZ0;
        if( x1MinusX0 )
        {
                c1  = ( p100 - p000 ) * oneByX1MinusX0;
                c1 *= dx;
        }
        else
        {
                c1 = black;

        }
        if( y1MinusY0 )
        {
                c2  = ( p010 - p000 ) * oneByY1MinusY0;
                c2 *= dy;
        }
        else
                c2 = black;
        if( z1MinusZ0 )
        {
                c3  = ( p001 - p000 ) * oneByZ1MinusZ0;
                c3 *= dz;
        }
        else
                c3 = black;
        if( x1MinusX0 * y1MinusY0 )
        {
                c4  = ( p110 - p010 - p100 + p000 ) * ( oneByX1MinusX0 * oneByY1MinusY0 );
                c4 *= dx * dy;
        }
        else
                c4 = black;
        if( x1MinusX0 * z1MinusZ0 )
        {
                c5  = ( p101 - p001 - p100 + p000 ) * ( oneByX1MinusX0 * oneByZ1MinusZ0 );
                c5 *= dx * dz;
        }
        else
                c6 = black;
        if( y1MinusY0 * z1MinusZ0 )
        {
                c6  = ( p011 - p001 - p010 + p000 ) * ( oneByY1MinusY0 * oneByZ1MinusZ0 );
                c6 *= dy * dz;
        }
        else
                c6 = black;
        if( x1MinusX0 * y1MinusY0 * z1MinusZ0 )
        {
                c7  = ( p111 - p011 - p101 - p110 + p100 + p001 + p010 - p000 ) * ( oneByX1MinusX0 * oneByY1MinusY0 * oneByZ1MinusZ0 );
                c7 *= dx * dy * dz;
        }
        else
                c7 = black;

        return Color( c0.x + c1.x  + c2.x  + c3.x  + c4.x  + c5.x  + c6.x  + c7.x,
                      c0.y + c1.y  + c2.y  + c3.y  + c4.y  + c5.y  + c6.y  + c7.y,
                      c0.z + c1.z  + c2.z  + c3.z  + c4.z  + c5.z  + c6.z  + c7.z );
}

};