Method PickTriangles

GTE/Graphics/Picker.cpp:254–300

void Picker::PickTriangles(std::shared_ptr<Visual> const& visual, char const* positions,
    uint32_t vstride, IndexBuffer* ibuffer, Line3<float> const& line)
{
    // Partition the items for multiple threads.
    auto const firstTriangle = ibuffer->GetFirstPrimitive();
    auto const numTriangles = ibuffer->GetNumActivePrimitives();
    auto const numThreads = std::min(numTriangles, mNumThreads);

    if (numThreads > 1)
    {
        auto const numPerThread = numTriangles / numThreads;
        std::vector<int32_t> imin(numThreads), imax(numThreads);
        for (uint32_t t = 0; t < numThreads; ++t)
        {
            imin[t] = firstTriangle + t * numPerThread;
            imax[t] = imin[t] + numPerThread - 1;
        }
        imax[static_cast<size_t>(numThreads) - 1] = firstTriangle + numTriangles - 1;

        // Process blocks of items in multiple threads.
        std::vector<std::thread> process(numThreads);
        std::vector<std::vector<PickRecord>> threadOutputs(numThreads);
        for (uint32_t t = 0; t < numThreads; ++t)
        {
            auto const i0 = imin[t];
            auto const i1 = imax[t];
            process[t] = std::thread(
                [this, t, visual, positions, vstride, ibuffer, line, i0, i1, &threadOutputs]()
                {
                    PickTriangles(visual, positions, vstride, ibuffer, line,
                        i0, i1, threadOutputs[t]);
                });
        }

        // Wait for all threads to finish.
        for (uint32_t t = 0; t < numThreads; ++t)
        {
            process[t].join();
            std::copy(threadOutputs[t].begin(), threadOutputs[t].end(), std::back_inserter(records));
        }
    }
    else
    {
        PickTriangles(visual, positions, vstride, ibuffer, line,
            firstTriangle, firstTriangle + numTriangles - 1, records);
    }
}

void Picker::PickTriangles(std::shared_ptr<Visual> const& visual, char const* positions,
    uint32_t vstride, IndexBuffer* ibuffer, Line3<float> const& line,