linearimage_texture.hpp

#ifndef PASTELGFX_LINEARIMAGE_TEXTURE_HPP
#define PASTELGFX_LINEARIMAGE_TEXTURE_HPP

#include "pastel/gfx/texture/linearimage_texture.h"

#include "pastel/sys/vector/vector_tools.h"

namespace Pastel
{

    template <typename Type, int N>
    Type sampleLinear(
        const Vector<dreal, N>& uv,
        const Array<Type, N>& image,
        const ArrayExtender<N, Type>& extender)
    {
        if (image.empty())
        {
            return Type();
        }

        // Gather all the neighboring 2^n samples.

        integer n = uv.size();
        integer samples = (integer)1 << n;

        Vector<integer, N> x = floor(uv - 0.5);
        Vector<dreal, N> st = (uv - 0.5) - Vector<dreal, N>(x);
        Tuple<Type, ModifyN<N, 1 << N>> valueSet(ofDimension(samples));
        Tuple<bool, N> s(ofDimension(n), false);

        for (integer i = 0;i < samples;++i)
        {
            valueSet[i] = extender(image, x);

            integer axis = 0;
            while(axis < N)
            {
                if (s[axis])
                {
                    s[axis] = false;
                    --x[axis];
                }
                else
                {
                    s[axis] = true;
                    ++x[axis];
                    break;
                }
                ++axis;
            }
        }

        return linear(st, 
            range(valueSet.begin(), valueSet.end()));
    }

}

#endif