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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_ENCODING_TRANSFORM_H_
#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_ENCODING_TRANSFORM_H_
#include "draco/compression/config/compression_shared.h"
#include "draco/core/encoder_buffer.h"
namespace draco {
// PredictionSchemeEncodingTransform is used to transform predicted values into
// correction values.
// CorrTypeT is the data type used for storing corrected values. It allows
// transforms to store corrections into a different type or format compared to
// the predicted data.
template <typename DataTypeT, typename CorrTypeT>
class PredictionSchemeEncodingTransform {
public:
typedef CorrTypeT CorrType;
PredictionSchemeEncodingTransform() : num_components_(0) {}
PredictionSchemeTransformType GetType() const {
return PREDICTION_TRANSFORM_DELTA;
}
// Performs any custom initialization of the transform for the encoder.
// |size| = total number of values in |orig_data| (i.e., number of entries *
// number of components).
void Init(const DataTypeT * /* orig_data */, int /* size */,
int num_components) {
num_components_ = num_components;
}
// Computes the corrections based on the input original values and the
// predicted values. The correction is always computed for all components
// of the input element. |val_id| is the id of the input value
// (i.e., element_id * num_components). The default implementation is equal to
// std::minus.
inline void ComputeCorrection(const DataTypeT *original_vals,
const DataTypeT *predicted_vals,
CorrTypeT *out_corr_vals) {
static_assert(std::is_same<DataTypeT, CorrTypeT>::value,
"For the default prediction transform, correction and input "
"data must be of the same type.");
for (int i = 0; i < num_components_; ++i) {
out_corr_vals[i] = original_vals[i] - predicted_vals[i];
}
}
// Encode any transform specific data.
bool EncodeTransformData(EncoderBuffer * /* buffer */) { return true; }
// Should return true if all corrected values are guaranteed to be positive.
bool AreCorrectionsPositive() const { return false; }
protected:
int num_components() const { return num_components_; }
private:
int num_components_;
};
} // namespace draco
#endif // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_ENCODING_TRANSFORM_H_
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