bilinear texture sample with clamping

SampleClamp2D.cpp

//==================================================================
template <typename _T>
inline _T SampleClamp2D(
                    const DVec<_T> &samp,
                    int sampW,
                    int sampH,
                    float u,
                    float v )
{
    u = std::max( u, _T(0) ); // only clamp to min.. max comes below
    v = std::max( v, _T(0) );

    auto ui0 = (float)sampW * u;
    auto ui0_int = std::min( (int)ui0, sampW-1 );
    auto tu_sub = ui0 - (float)ui0_int;
    auto ui1_int = std::min( ui0_int+1, sampW-1 );

    auto vi0 = (float)sampH * v;
    auto vi0_int = std::min( (int)vi0, sampH-1 );
    auto tv_sub = vi0 - (float)vi0_int;
    auto vi1_int = std::min( vi0_int+1, sampH-1 );

    auto off0 = vi0_int * sampW;
    auto off1 = vi1_int * sampW;
    auto val_u_v0 = DLerp( samp[ui0_int + off0], samp[ui1_int + off0], tu_sub );
    auto val_u_v1 = DLerp( samp[ui0_int + off1], samp[ui1_int + off1], tu_sub );

    return DLerp( val_u_v0, val_u_v1, tv_sub );
}