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Diffstat (limited to 'extern/draco/draco/src/draco/compression/attributes/prediction_schemes/prediction_scheme_normal_octahedron_canonicalized_encoding_transform.h')
-rw-r--r-- | extern/draco/draco/src/draco/compression/attributes/prediction_schemes/prediction_scheme_normal_octahedron_canonicalized_encoding_transform.h | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/extern/draco/draco/src/draco/compression/attributes/prediction_schemes/prediction_scheme_normal_octahedron_canonicalized_encoding_transform.h b/extern/draco/draco/src/draco/compression/attributes/prediction_schemes/prediction_scheme_normal_octahedron_canonicalized_encoding_transform.h new file mode 100644 index 00000000000..0dc96967b10 --- /dev/null +++ b/extern/draco/draco/src/draco/compression/attributes/prediction_schemes/prediction_scheme_normal_octahedron_canonicalized_encoding_transform.h @@ -0,0 +1,116 @@ +// 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_NORMAL_OCTAHEDRON_CANONICALIZED_ENCODING_TRANSFORM_H_ +#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_NORMAL_OCTAHEDRON_CANONICALIZED_ENCODING_TRANSFORM_H_ + +#include <cmath> + +#include "draco/compression/attributes/normal_compression_utils.h" +#include "draco/compression/attributes/prediction_schemes/prediction_scheme_normal_octahedron_canonicalized_transform_base.h" +#include "draco/core/encoder_buffer.h" +#include "draco/core/macros.h" +#include "draco/core/vector_d.h" + +namespace draco { + +// The transform works on octahedral coordinates for normals. The square is +// subdivided into four inner triangles (diamond) and four outer triangles. The +// inner triangles are associated with the upper part of the octahedron and the +// outer triangles are associated with the lower part. +// Given a prediction value P and the actual value Q that should be encoded, +// this transform first checks if P is outside the diamond. If so, the outer +// triangles are flipped towards the inside and vice versa. Then it checks if p +// is in the bottom left quadrant. If it is not, it rotates p and q accordingly. +// The actual correction value is then based on the mapped and rotated P and Q +// values. The inversion tends to result in shorter correction vectors and the +// rotation makes it so that all long correction values are positive, reducing +// the possible value range of the correction values and increasing the +// occurrences of positive large correction values, which helps the entropy +// encoder. This is possible since P is also known by the decoder, see also +// ComputeCorrection and ComputeOriginalValue functions. +// Note that the tile is not periodic, which implies that the outer edges can +// not be identified, which requires us to use an odd number of values on each +// axis. +// DataTypeT is expected to be some integral type. +// +template <typename DataTypeT> +class PredictionSchemeNormalOctahedronCanonicalizedEncodingTransform + : public PredictionSchemeNormalOctahedronCanonicalizedTransformBase< + DataTypeT> { + public: + typedef PredictionSchemeNormalOctahedronCanonicalizedTransformBase<DataTypeT> + Base; + typedef VectorD<DataTypeT, 2> Point2; + typedef DataTypeT CorrType; + typedef DataTypeT DataType; + + // We expect the mod value to be of the form 2^b-1. + explicit PredictionSchemeNormalOctahedronCanonicalizedEncodingTransform( + DataType max_quantized_value) + : Base(max_quantized_value) {} + + // Dummy function to fulfill concept. + void Init(const DataTypeT *orig_data, int size, int num_components) {} + + bool EncodeTransformData(EncoderBuffer *buffer) { + buffer->Encode(this->max_quantized_value()); + buffer->Encode(this->center_value()); + return true; + } + + inline void ComputeCorrection(const DataType *orig_vals, + const DataType *pred_vals, + CorrType *out_corr_vals) const { + DRACO_DCHECK_LE(pred_vals[0], this->center_value() * 2); + DRACO_DCHECK_LE(pred_vals[1], this->center_value() * 2); + DRACO_DCHECK_LE(orig_vals[0], this->center_value() * 2); + DRACO_DCHECK_LE(orig_vals[1], this->center_value() * 2); + DRACO_DCHECK_LE(0, pred_vals[0]); + DRACO_DCHECK_LE(0, pred_vals[1]); + DRACO_DCHECK_LE(0, orig_vals[0]); + DRACO_DCHECK_LE(0, orig_vals[1]); + + const Point2 orig = Point2(orig_vals[0], orig_vals[1]); + const Point2 pred = Point2(pred_vals[0], pred_vals[1]); + const Point2 corr = ComputeCorrection(orig, pred); + + out_corr_vals[0] = corr[0]; + out_corr_vals[1] = corr[1]; + } + + private: + Point2 ComputeCorrection(Point2 orig, Point2 pred) const { + const Point2 t(this->center_value(), this->center_value()); + orig = orig - t; + pred = pred - t; + if (!this->IsInDiamond(pred[0], pred[1])) { + this->InvertDiamond(&orig[0], &orig[1]); + this->InvertDiamond(&pred[0], &pred[1]); + } + if (!this->IsInBottomLeft(pred)) { + const int32_t rotation_count = this->GetRotationCount(pred); + orig = this->RotatePoint(orig, rotation_count); + pred = this->RotatePoint(pred, rotation_count); + } + Point2 corr = orig - pred; + corr[0] = this->MakePositive(corr[0]); + corr[1] = this->MakePositive(corr[1]); + return corr; + } +}; + +} // namespace draco + +#endif // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_NORMAL_OCTAHEDRON_CANONICALIZED_ENCODING_TRANSFORM_H_ |