Function BuildRoadAltitudes

generator/altitude_generator.cpp:133–208

}  // namespace

void BuildRoadAltitudes(std::string const & mwmPath, AltitudeGetter & altitudeGetter)
{
  try
  {
    // Preparing altitude information.
    Processor processor(altitudeGetter);
    feature::ForEachFeature(mwmPath, processor);
    processor.m_altitudeGetter.PrintStatsAndPurge();

    if (!processor.HasAltitudeInfo())
    {
      // Possible for small islands like Bouvet or Willis.
      LOG(LWARNING, ("No altitude information for road features of mwm:", mwmPath));
      return;
    }

    FilesContainerW cont(mwmPath, FileWriter::OP_WRITE_EXISTING);
    auto w = cont.GetWriter(ALTITUDES_FILE_TAG);

    AltitudeHeader header;
    header.m_minAltitude = processor.m_minAltitude;

    auto const startOffset = w->Pos();
    header.Serialize(*w);
    {
      // Altitude availability serialization.
      coding::FreezeVisitor<Writer> visitor(*w);
      succinct::rs_bit_vector(&processor.m_altitudeAvailabilityBuilder).map(visitor);
    }
    header.m_featureTableOffset = base::checked_cast<uint32_t>(w->Pos() - startOffset);

    std::vector<uint32_t> offsets;
    std::vector<uint8_t> deltas;
    {
      // Altitude info serialization to memory.
      MemWriter<std::vector<uint8_t>> writer(deltas);
      for (auto const & a : processor.m_featureAltitudes)
      {
        offsets.push_back(base::checked_cast<uint32_t>(writer.Pos()));
        a.m_altitudes.Serialize(header.m_minAltitude, writer);
      }
    }
    {
      // Altitude offsets serialization.
      CHECK(base::IsSortedAndUnique(offsets), ());

      succinct::elias_fano::elias_fano_builder builder(offsets.back(), offsets.size());
      for (uint32_t offset : offsets)
        builder.push_back(offset);

      coding::FreezeVisitor<Writer> visitor(*w);
      succinct::elias_fano(&builder).map(visitor);
    }
    // Writing altitude info.
    header.m_altitudesOffset = base::checked_cast<uint32_t>(w->Pos() - startOffset);
    w->Write(deltas.data(), deltas.size());
    w->WritePaddingByEnd(8);
    header.m_endOffset = base::checked_cast<uint32_t>(w->Pos() - startOffset);