prediction_scheme_encoder.h

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// 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_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_ENCODER_H_
#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_ENCODER_H_
 
#include <type_traits>
 
#include "draco/compression/attributes/prediction_schemes/prediction_scheme_encoder_interface.h"
#include "draco/compression/attributes/prediction_schemes/prediction_scheme_encoding_transform.h"
 
// Prediction schemes can be used during encoding and decoding of vertex
// attributes to predict attribute values based on the previously
// encoded/decoded data. The differences between the original and predicted
// attribute values are used to compute correction values that can be usually
// encoded with fewer bits compared to the original data.
namespace draco {
 
// Abstract base class for typed prediction schemes. It provides basic access
// to the encoded attribute and to the supplied prediction transform.
template <typename DataTypeT,
          class TransformT =
              PredictionSchemeEncodingTransform<DataTypeT, DataTypeT>>
class PredictionSchemeEncoder : public PredictionSchemeTypedEncoderInterface<
                                    DataTypeT, typename TransformT::CorrType> {
 public:
  typedef DataTypeT DataType;
  typedef TransformT Transform;
  // Correction type needs to be defined in the prediction transform class.
  typedef typename Transform::CorrType CorrType;
  explicit PredictionSchemeEncoder(const PointAttribute *attribute)
      : PredictionSchemeEncoder(attribute, Transform()) {}
  PredictionSchemeEncoder(const PointAttribute *attribute,
                          const Transform &transform)
      : attribute_(attribute), transform_(transform) {}
 
  bool EncodePredictionData(EncoderBuffer *buffer) override {
    if (!transform_.EncodeTransformData(buffer)) {
      return false;
    }
    return true;
  }
 
  const PointAttribute *GetAttribute() const override { return attribute(); }
 
  // Returns the number of parent attributes that are needed for the prediction.
  int GetNumParentAttributes() const override { return 0; }
 
  // Returns the type of each of the parent attribute.
  GeometryAttribute::Type GetParentAttributeType(int /* i */) const override {
    return GeometryAttribute::INVALID;
  }
 
  // Sets the required parent attribute.
  bool SetParentAttribute(const PointAttribute * /* att */) override {
    return false;
  }
 
  bool AreCorrectionsPositive() override {
    return transform_.AreCorrectionsPositive();
  }
 
  PredictionSchemeTransformType GetTransformType() const override {
    return transform_.GetType();
  }
 
 protected:
  inline const PointAttribute *attribute() const { return attribute_; }
  inline const Transform &transform() const { return transform_; }
  inline Transform &transform() { return transform_; }
 
 private:
  const PointAttribute *attribute_;
  Transform transform_;
};
 
}  // namespace draco
 
#endif  // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_ENCODER_H_