Method initialize

src/OpenColorIO/ops/lut3d/Lut3DOpCPU.cpp:1306–1388

}

void InvLut3DRenderer::RangeTree::initialize(float *grvec, unsigned long gsz)
{
    m_chans = 3;  // only supporting Lut3D for now
    m_gsz[0] = m_gsz[1] = m_gsz[2] = gsz;
    m_gsz[3] = 0;

    // Determine depth of tree.
    float maxGsz = 0.f;
    for (unsigned long i = 0; i<m_chans; i++)
    {
        maxGsz = std::max(maxGsz, (float)m_gsz[i]);
    }
    int log2base;
    frexp(maxGsz - 2.f, &log2base);
    m_depth = (unsigned long)log2base;

    m_levels.resize(m_depth);

    // Determine size of each level.
    for (unsigned long i = 0; i < m_depth; i++)
    {
        unsigned long levelSize = 1;
        for (unsigned long j = 0; j < m_chans; j++)
        {
            unsigned long g = m_gsz[j] - 2;
            unsigned long m = g >> (((int)m_depth) - 1 - i);
            levelSize *= (m + 1);
        }
        m_levels[i].elems = levelSize;
        m_levels[i].chans = m_chans;
    }

    // Determine scale to use for hash.
    m_levelScales.resize(m_depth);
    for (unsigned long level = 0; level < m_depth; level++)
    {
        const unsigned long depthm1 = m_depth - 1;
        const unsigned long shift = (m_chans + 1) * (depthm1 - level);
        const unsigned long scale = 1 << shift;
        m_levelScales[level] = scale;
    }

    // Initialize indices into 3d-LUT.
    initInds();

    // Calculate hash for indices.

    const unsigned long cnt = static_cast<unsigned long>(m_baseInds.size());
    for (unsigned long i = 0; i < cnt; i++)
    {
        indsToHash(i);
    }

    // Sort indices based on hash.
    std::sort(m_baseInds.begin(), m_baseInds.end());

    // Copy sorted hashes into temp vector.
    ulongVector hashes(cnt);