text: // Copyright 2016 The Draco Authors.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //      http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  //
  #ifndef DRACO_COMPRESSION_POINT_CLOUD_ALGORITHMS_FLOAT_POINTS_TREE_ENCODER_H_
  #define DRACO_COMPRESSION_POINT_CLOUD_ALGORITHMS_FLOAT_POINTS_TREE_ENCODER_H_
  
  #include <memory>
  #include <vector>
  
  #include "draco/compression/point_cloud/algorithms/point_cloud_compression_method.h"
  #include "draco/compression/point_cloud/algorithms/point_cloud_types.h"
  #include "draco/compression/point_cloud/algorithms/quantize_points_3.h"
  #include "draco/core/encoder_buffer.h"
  
  namespace draco {
  
  // This class encodes a given point cloud based on the point cloud compression
  // algorithm in:
  // Olivier Devillers and Pierre-Marie Gandoin
  // "Geometric compression for interactive transmission"
  //
  // In principle the algorithm keeps on splitting the point cloud in the middle
  // while alternating the axes. For 3D this results in an Octree like structure.
  // In each step we encode the number of points in the first half.
  // The algorithm uses quantization and does not preserve the order of points.
  //
  // However, the algorithm here differs from the original as follows:
  // The algorithm keeps on splitting the point cloud in the middle of the axis
  // that keeps the point cloud as clustered as possible, which gives a better
  // compression rate.
  // The number of points is encode by the deviation from the half of the points
  // in the smaller half of the two. This results in a better compression rate as
  // there are more leading zeros, which is then compressed better by the
  // arithmetic encoding.
  
  // TODO(b/199760123): Remove class because it duplicates quantization code.
  class FloatPointsTreeEncoder {
   public:
    explicit FloatPointsTreeEncoder(PointCloudCompressionMethod method);
    explicit FloatPointsTreeEncoder(PointCloudCompressionMethod method,
                                    uint32_t quantization_bits,
                                    uint32_t compression_level);
  
    template <class InputIteratorT>
    bool EncodePointCloud(InputIteratorT points_begin, InputIteratorT points_end);
    EncoderBuffer *buffer() { return &buffer_; }
  
    uint32_t version() const { return version_; }
    uint32_t quantization_bits() const { return qinfo_.quantization_bits; }
    uint32_t &quantization_bits() { return qinfo_.quantization_bits; }
    uint32_t compression_level() const { return compression_level_; }
    uint32_t &compression_level() { return compression_level_; }
    float range() const { return qinfo_.range; }
    uint32_t num_points() const { return num_points_; }
    std::string identification_string() const {
      if (method_ == KDTREE) {
        return "FloatPointsTreeEncoder: IntegerPointsKDTreeEncoder";
      } else {
        return "FloatPointsTreeEncoder: Unsupported Method";
      }
    }
  
   private:
    void Clear() { buffer_.Clear(); }
    bool EncodePointCloudKdTreeInternal(std::vector<Point3ui> *qpoints);
  
    static const uint32_t version_;
    QuantizationInfo qinfo_;
    PointCloudCompressionMethod method_;
    uint32_t num_points_;
    EncoderBuffer buffer_;
    uint32_t compression_level_;
  };
  
  template <class InputIteratorT>
  bool FloatPointsTreeEncoder::EncodePointCloud(InputIteratorT points_begin,
                                                InputIteratorT points_end) {
    Clear();
  
    // Collect necessary data for encoding.
    num_points_ = std::distance(points_begin, points_end);
  
    // TODO(b/199760123): Extend quantization tools to make this more automatic.
    // Compute range of points for quantization
    std::vector<Point3ui> qpoints;
    qpoints.reserve(num_points_);
    QuantizePoints3(points_begin, points_end, &qinfo_,
                    std::back_inserter(qpoints));
  
    // Encode header.
    buffer()->Encode(version_);
    buffer()->Encode(static_cast<int8_t>(method_));
    buffer()->Encode(qinfo_.quantization_bits);
    buffer()->Encode(qinfo_.range);
    buffer()->Encode(num_points_);
  
    if (method_ == KDTREE) {
      buffer()->Encode(compression_level_);
    }
  
    if (num_points_ == 0) {
      return true;
    }
  
    if (method_ == KDTREE) {
      return EncodePointCloudKdTreeInternal(&qpoints);
    } else {  // Unsupported method.
      fprintf(stderr, "Method not supported. \n");
      return false;
    }
  }
  
  }  // namespace draco
  
  #endif  // DRACO_COMPRESSION_POINT_CLOUD_ALGORITHMS_FLOAT_POINTS_TREE_ENCODER_H_
  