Function ExportDataSparse

code/AssetLib/glTF2/glTF2Exporter.cpp:318–398

}

inline Ref<Accessor> ExportDataSparse(Asset &a, std::string &meshName, Ref<Buffer> &buffer,
        size_t count, void *data, AttribType::Value typeIn, AttribType::Value typeOut, ComponentType compType, BufferViewTarget target = BufferViewTarget_NONE, void *dataBase = nullptr) {
    if (!count || !data) {
        return Ref<Accessor>();
    }

    unsigned int numCompsIn = AttribType::GetNumComponents(typeIn);
    unsigned int numCompsOut = AttribType::GetNumComponents(typeOut);
    unsigned int bytesPerComp = ComponentTypeSize(compType);

    // accessor
    Ref<Accessor> acc = a.accessors.Create(a.FindUniqueID(meshName, "accessor"));

    // if there is a basic data vector
    if (dataBase) {
        size_t base_offset = buffer->byteLength;
        size_t base_padding = base_offset % bytesPerComp;
        base_offset += base_padding;
        size_t base_length = count * numCompsOut * bytesPerComp;
        buffer->Grow(base_length + base_padding);

        Ref<BufferView> bv = a.bufferViews.Create(a.FindUniqueID(meshName, "view"));
        bv->buffer = buffer;
        bv->byteOffset = base_offset;
        bv->byteLength = base_length; //! The target that the WebGL buffer should be bound to.
        bv->byteStride = 0;
        bv->target = target;
        acc->bufferView = bv;
        acc->WriteData(count, dataBase, numCompsIn * bytesPerComp);
    }
    acc->byteOffset = 0;
    acc->componentType = compType;
    acc->count = count;
    acc->type = typeOut;

    if (data) {
        void *nzDiff = nullptr, *nzIdx = nullptr;
        size_t nzCount = NZDiff(compType, data, dataBase, count, numCompsIn, numCompsOut, nzDiff, nzIdx);
        acc->sparse.reset(new Accessor::Sparse);
        acc->sparse->count = nzCount;

        // indices
        unsigned int bytesPerIdx = sizeof(unsigned short);
        size_t indices_offset = buffer->byteLength;
        size_t indices_padding = indices_offset % bytesPerIdx;
        indices_offset += indices_padding;
        size_t indices_length = nzCount * 1 * bytesPerIdx;
        buffer->Grow(indices_length + indices_padding);

        Ref<BufferView> indicesBV = a.bufferViews.Create(a.FindUniqueID(meshName, "view"));
        indicesBV->buffer = buffer;
        indicesBV->byteOffset = indices_offset;
        indicesBV->byteLength = indices_length;
        indicesBV->byteStride = 0;
        acc->sparse->indices = indicesBV;
        acc->sparse->indicesType = ComponentType_UNSIGNED_SHORT;
        acc->sparse->indicesByteOffset = 0;
        acc->WriteSparseIndices(nzCount, nzIdx, 1 * bytesPerIdx);