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// Copyright 2017 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_MESH_PREDICTION_SCHEME_GEOMETRIC_NORMAL_ENCODER_H_
#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_GEOMETRIC_NORMAL_ENCODER_H_
#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_encoder.h"
#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_geometric_normal_predictor_area.h"
#include "draco/compression/bit_coders/rans_bit_encoder.h"
#include "draco/compression/config/compression_shared.h"
namespace draco {
// Prediction scheme for normals based on the underlying geometry.
// At a smooth vertices normals are computed by weighting the normals of
// adjacent faces with the area of these faces. At seams, the same approach
// applies for seam corners.
template <typename DataTypeT, class TransformT, class MeshDataT>
class MeshPredictionSchemeGeometricNormalEncoder
: public MeshPredictionSchemeEncoder<DataTypeT, TransformT, MeshDataT> {
public:
using CorrType = typename MeshPredictionSchemeEncoder<DataTypeT, TransformT,
MeshDataT>::CorrType;
MeshPredictionSchemeGeometricNormalEncoder(const PointAttribute *attribute,
const TransformT &transform,
const MeshDataT &mesh_data)
: MeshPredictionSchemeEncoder<DataTypeT, TransformT, MeshDataT>(
attribute, transform, mesh_data),
predictor_(mesh_data) {}
bool ComputeCorrectionValues(
const DataTypeT *in_data, CorrType *out_corr, int size,
int num_components, const PointIndex *entry_to_point_id_map) override;
bool EncodePredictionData(EncoderBuffer *buffer) override;
PredictionSchemeMethod GetPredictionMethod() const override {
return MESH_PREDICTION_GEOMETRIC_NORMAL;
}
bool IsInitialized() const override {
if (!predictor_.IsInitialized()) {
return false;
}
if (!this->mesh_data().IsInitialized()) {
return false;
}
return true;
}
int GetNumParentAttributes() const override { return 1; }
GeometryAttribute::Type GetParentAttributeType(int i) const override {
DRACO_DCHECK_EQ(i, 0);
(void)i;
return GeometryAttribute::POSITION;
}
bool SetParentAttribute(const PointAttribute *att) override {
if (att->attribute_type() != GeometryAttribute::POSITION) {
return false; // Invalid attribute type.
}
if (att->num_components() != 3) {
return false; // Currently works only for 3 component positions.
}
predictor_.SetPositionAttribute(*att);
return true;
}
private:
void SetQuantizationBits(int q) {
DRACO_DCHECK_GE(q, 2);
DRACO_DCHECK_LE(q, 30);
octahedron_tool_box_.SetQuantizationBits(q);
}
MeshPredictionSchemeGeometricNormalPredictorArea<DataTypeT, TransformT,
MeshDataT>
predictor_;
OctahedronToolBox octahedron_tool_box_;
RAnsBitEncoder flip_normal_bit_encoder_;
};
template <typename DataTypeT, class TransformT, class MeshDataT>
bool MeshPredictionSchemeGeometricNormalEncoder<DataTypeT, TransformT,
MeshDataT>::
ComputeCorrectionValues(const DataTypeT *in_data, CorrType *out_corr,
int size, int num_components,
const PointIndex *entry_to_point_id_map) {
this->SetQuantizationBits(this->transform().quantization_bits());
predictor_.SetEntryToPointIdMap(entry_to_point_id_map);
DRACO_DCHECK(this->IsInitialized());
// Expecting in_data in octahedral coordinates, i.e., portable attribute.
DRACO_DCHECK_EQ(num_components, 2);
flip_normal_bit_encoder_.StartEncoding();
const int corner_map_size =
static_cast<int>(this->mesh_data().data_to_corner_map()->size());
VectorD<int32_t, 3> pred_normal_3d;
VectorD<int32_t, 2> pos_pred_normal_oct;
VectorD<int32_t, 2> neg_pred_normal_oct;
VectorD<int32_t, 2> pos_correction;
VectorD<int32_t, 2> neg_correction;
for (int data_id = 0; data_id < corner_map_size; ++data_id) {
const CornerIndex corner_id =
this->mesh_data().data_to_corner_map()->at(data_id);
predictor_.ComputePredictedValue(corner_id, pred_normal_3d.data());
// Compute predicted octahedral coordinates.
octahedron_tool_box_.CanonicalizeIntegerVector(pred_normal_3d.data());
DRACO_DCHECK_EQ(pred_normal_3d.AbsSum(),
octahedron_tool_box_.center_value());
// Compute octahedral coordinates for both possible directions.
octahedron_tool_box_.IntegerVectorToQuantizedOctahedralCoords(
pred_normal_3d.data(), pos_pred_normal_oct.data(),
pos_pred_normal_oct.data() + 1);
pred_normal_3d = -pred_normal_3d;
octahedron_tool_box_.IntegerVectorToQuantizedOctahedralCoords(
pred_normal_3d.data(), neg_pred_normal_oct.data(),
neg_pred_normal_oct.data() + 1);
// Choose the one with the best correction value.
const int data_offset = data_id * 2;
this->transform().ComputeCorrection(in_data + data_offset,
pos_pred_normal_oct.data(),
pos_correction.data());
this->transform().ComputeCorrection(in_data + data_offset,
neg_pred_normal_oct.data(),
neg_correction.data());
pos_correction[0] = octahedron_tool_box_.ModMax(pos_correction[0]);
pos_correction[1] = octahedron_tool_box_.ModMax(pos_correction[1]);
neg_correction[0] = octahedron_tool_box_.ModMax(neg_correction[0]);
neg_correction[1] = octahedron_tool_box_.ModMax(neg_correction[1]);
if (pos_correction.AbsSum() < neg_correction.AbsSum()) {
flip_normal_bit_encoder_.EncodeBit(false);
(out_corr + data_offset)[0] =
octahedron_tool_box_.MakePositive(pos_correction[0]);
(out_corr + data_offset)[1] =
octahedron_tool_box_.MakePositive(pos_correction[1]);
} else {
flip_normal_bit_encoder_.EncodeBit(true);
(out_corr + data_offset)[0] =
octahedron_tool_box_.MakePositive(neg_correction[0]);
(out_corr + data_offset)[1] =
octahedron_tool_box_.MakePositive(neg_correction[1]);
}
}
return true;
}
template <typename DataTypeT, class TransformT, class MeshDataT>
bool MeshPredictionSchemeGeometricNormalEncoder<
DataTypeT, TransformT, MeshDataT>::EncodePredictionData(EncoderBuffer
*buffer) {
if (!this->transform().EncodeTransformData(buffer)) {
return false;
}
// Encode normal flips.
flip_normal_bit_encoder_.EndEncoding(buffer);
return true;
}
} // namespace draco
#endif // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_GEOMETRIC_NORMAL_ENCODER_H_
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