Method LoadStreamBuffer

IO/Geometry/vtkGLTFDocumentLoader.cxx:1568–1623

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bool vtkGLTFDocumentLoader::LoadStreamBuffer(
  vtkResourceStream* stream, std::vector<char>& glbBuffer)
{
  stream->Seek(this->GLBStart, vtkResourceStream::SeekDirection::Begin);

  // Get base information
  std::array<char, 4> magic;
  if (stream->Read(magic.data(), magic.size()) != magic.size())
  {
    return false;
  }

  if (std::strncmp(magic.data(), "glTF", 4) != 0)
  {
    return false;
  }

  std::uint32_t version;
  std::uint32_t fileLength;
  std::vector<vtkGLTFUtils::ChunkInfoType> chunkInfo;
  if (!vtkGLTFUtils::ExtractGLBFileInformation(
        stream, version, fileLength, this->GLBStart, chunkInfo))
  {
    vtkErrorMacro("Invalid .glb file");
    return false;
  }

  // Look for BIN chunk while updating fstream position
  stream->Seek(this->GLBStart + vtkGLTFUtils::GLBHeaderSize + vtkGLTFUtils::GLBChunkHeaderSize,
    vtkResourceStream::SeekDirection::Begin);
  for (auto& chunk : chunkInfo)
  {
    if (std::memcmp(chunk.first.data(), "BIN\0", 4) == 0)
    {
      // Read chunk data into output vector
      std::vector<char> binData;
      binData.resize(chunk.second);
      if (stream->Read(binData.data(), chunk.second) != chunk.second)
      {
        vtkErrorMacro("Failed to read BIN chunk from .glb file");
        return false;
      }

      glbBuffer.insert(glbBuffer.end(), binData.begin(), binData.begin() + chunk.second);

      return true;
    }

    // Jump to next chunk
    stream->Seek(
      chunk.second + vtkGLTFUtils::GLBChunkHeaderSize, vtkResourceStream::SeekDirection::Current);
  }

  vtkErrorMacro("Could not find any valid BIN chunks in file");
  return false;
}

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