Function NZDiff

code/AssetLib/glTF2/glTF2Exporter.cpp:249–298

// compute the (data-dataBase), store the non-zero data items
template <typename T>
size_t NZDiff(void *data, void *dataBase, size_t count, unsigned int numCompsIn, unsigned int numCompsOut, void *&outputNZDiff, void *&outputNZIdx) {
    std::vector<T> vNZDiff;
    std::vector<unsigned short> vNZIdx;
    size_t totalComps = count * numCompsIn;
    T *bufferData_ptr = static_cast<T *>(data);
    T *bufferData_end = bufferData_ptr + totalComps;
    T *bufferBase_ptr = static_cast<T *>(dataBase);

    // Search and set extreme values.
    for (short idx = 0; bufferData_ptr < bufferData_end; idx += 1, bufferData_ptr += numCompsIn) {
        bool bNonZero = false;

        // for the data, check any component Non Zero
        for (unsigned int j = 0; j < numCompsOut; j++) {
            double valueData = bufferData_ptr[j];
            double valueBase = bufferBase_ptr ? bufferBase_ptr[j] : 0;
            if ((valueData - valueBase) != 0) {
                bNonZero = true;
                break;
            }
        }

        // all zeros, continue
        if (!bNonZero)
            continue;

        // non zero, store the data
        for (unsigned int j = 0; j < numCompsOut; j++) {
            T valueData = bufferData_ptr[j];
            T valueBase = bufferBase_ptr ? bufferBase_ptr[j] : 0;
            vNZDiff.push_back(valueData - valueBase);
        }
        vNZIdx.push_back(idx);
    }

    // avoid all-0, put 1 item
    if (vNZDiff.size() == 0) {
        for (unsigned int j = 0; j < numCompsOut; j++)
            vNZDiff.push_back(0);
        vNZIdx.push_back(0);
    }

    // process data
    outputNZDiff = new T[vNZDiff.size()];
    memcpy(outputNZDiff, vNZDiff.data(), vNZDiff.size() * sizeof(T));

    outputNZIdx = new unsigned short[vNZIdx.size()];
    memcpy(outputNZIdx, vNZIdx.data(), vNZIdx.size() * sizeof(unsigned short));
    return vNZIdx.size();
}

inline size_t NZDiff(ComponentType compType, void *data, void *dataBase, size_t count, unsigned int numCompsIn, unsigned int numCompsOut, void *&nzDiff, void *&nzIdx) {
    switch (compType) {