1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
// 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_MESH_PREDICTION_SCHEME_CONSTRAINED_MULTI_PARALLELOGRAM_DECODER_H_
#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_CONSTRAINED_MULTI_PARALLELOGRAM_DECODER_H_
#include <algorithm>
#include <cmath>
#include "draco/draco_features.h"
#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_constrained_multi_parallelogram_shared.h"
#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_decoder.h"
#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_parallelogram_shared.h"
#include "draco/compression/bit_coders/rans_bit_decoder.h"
#include "draco/core/varint_decoding.h"
namespace draco {
// Decoder for predictions encoded with the constrained multi-parallelogram
// encoder. See the corresponding encoder for more details about the prediction
// method.
template <typename DataTypeT, class TransformT, class MeshDataT>
class MeshPredictionSchemeConstrainedMultiParallelogramDecoder
: public MeshPredictionSchemeDecoder<DataTypeT, TransformT, MeshDataT> {
public:
using CorrType =
typename PredictionSchemeDecoder<DataTypeT, TransformT>::CorrType;
using CornerTable = typename MeshDataT::CornerTable;
explicit MeshPredictionSchemeConstrainedMultiParallelogramDecoder(
const PointAttribute *attribute)
: MeshPredictionSchemeDecoder<DataTypeT, TransformT, MeshDataT>(
attribute),
selected_mode_(Mode::OPTIMAL_MULTI_PARALLELOGRAM) {}
MeshPredictionSchemeConstrainedMultiParallelogramDecoder(
const PointAttribute *attribute, const TransformT &transform,
const MeshDataT &mesh_data)
: MeshPredictionSchemeDecoder<DataTypeT, TransformT, MeshDataT>(
attribute, transform, mesh_data),
selected_mode_(Mode::OPTIMAL_MULTI_PARALLELOGRAM) {}
bool ComputeOriginalValues(const CorrType *in_corr, DataTypeT *out_data,
int size, int num_components,
const PointIndex *entry_to_point_id_map) override;
bool DecodePredictionData(DecoderBuffer *buffer) override;
PredictionSchemeMethod GetPredictionMethod() const override {
return MESH_PREDICTION_CONSTRAINED_MULTI_PARALLELOGRAM;
}
bool IsInitialized() const override {
return this->mesh_data().IsInitialized();
}
private:
typedef constrained_multi_parallelogram::Mode Mode;
static constexpr int kMaxNumParallelograms =
constrained_multi_parallelogram::kMaxNumParallelograms;
// Crease edges are used to store whether any given edge should be used for
// parallelogram prediction or not. New values are added in the order in which
// the edges are processed. For better compression, the flags are stored in
// in separate contexts based on the number of available parallelograms at a
// given vertex.
std::vector<bool> is_crease_edge_[kMaxNumParallelograms];
Mode selected_mode_;
};
template <typename DataTypeT, class TransformT, class MeshDataT>
bool MeshPredictionSchemeConstrainedMultiParallelogramDecoder<
DataTypeT, TransformT, MeshDataT>::
ComputeOriginalValues(const CorrType *in_corr, DataTypeT *out_data,
int /* size */, int num_components,
const PointIndex * /* entry_to_point_id_map */) {
this->transform().Init(num_components);
// Predicted values for all simple parallelograms encountered at any given
// vertex.
std::vector<DataTypeT> pred_vals[kMaxNumParallelograms];
for (int i = 0; i < kMaxNumParallelograms; ++i) {
pred_vals[i].resize(num_components, 0);
}
this->transform().ComputeOriginalValue(pred_vals[0].data(), in_corr,
out_data);
const CornerTable *const table = this->mesh_data().corner_table();
const std::vector<int32_t> *const vertex_to_data_map =
this->mesh_data().vertex_to_data_map();
// Current position in the |is_crease_edge_| array for each context.
std::vector<int> is_crease_edge_pos(kMaxNumParallelograms, 0);
// Used to store predicted value for multi-parallelogram prediction.
std::vector<DataTypeT> multi_pred_vals(num_components);
const int corner_map_size =
static_cast<int>(this->mesh_data().data_to_corner_map()->size());
for (int p = 1; p < corner_map_size; ++p) {
const CornerIndex start_corner_id =
this->mesh_data().data_to_corner_map()->at(p);
CornerIndex corner_id(start_corner_id);
int num_parallelograms = 0;
bool first_pass = true;
while (corner_id != kInvalidCornerIndex) {
if (ComputeParallelogramPrediction(
p, corner_id, table, *vertex_to_data_map, out_data,
num_components, &(pred_vals[num_parallelograms][0]))) {
// Parallelogram prediction applied and stored in
// |pred_vals[num_parallelograms]|
++num_parallelograms;
// Stop processing when we reach the maximum number of allowed
// parallelograms.
if (num_parallelograms == kMaxNumParallelograms)
break;
}
// Proceed to the next corner attached to the vertex. First swing left
// and if we reach a boundary, swing right from the start corner.
if (first_pass) {
corner_id = table->SwingLeft(corner_id);
} else {
corner_id = table->SwingRight(corner_id);
}
if (corner_id == start_corner_id) {
break;
}
if (corner_id == kInvalidCornerIndex && first_pass) {
first_pass = false;
corner_id = table->SwingRight(start_corner_id);
}
}
// Check which of the available parallelograms are actually used and compute
// the final predicted value.
int num_used_parallelograms = 0;
if (num_parallelograms > 0) {
for (int i = 0; i < num_components; ++i) {
multi_pred_vals[i] = 0;
}
// Check which parallelograms are actually used.
for (int i = 0; i < num_parallelograms; ++i) {
const int context = num_parallelograms - 1;
const int pos = is_crease_edge_pos[context]++;
if (is_crease_edge_[context].size() <= pos)
return false;
const bool is_crease = is_crease_edge_[context][pos];
if (!is_crease) {
++num_used_parallelograms;
for (int j = 0; j < num_components; ++j) {
multi_pred_vals[j] += pred_vals[i][j];
}
}
}
}
const int dst_offset = p * num_components;
if (num_used_parallelograms == 0) {
// No parallelogram was valid.
// We use the last decoded point as a reference.
const int src_offset = (p - 1) * num_components;
this->transform().ComputeOriginalValue(
out_data + src_offset, in_corr + dst_offset, out_data + dst_offset);
} else {
// Compute the correction from the predicted value.
for (int c = 0; c < num_components; ++c) {
multi_pred_vals[c] /= num_used_parallelograms;
}
this->transform().ComputeOriginalValue(
multi_pred_vals.data(), in_corr + dst_offset, out_data + dst_offset);
}
}
return true;
}
template <typename DataTypeT, class TransformT, class MeshDataT>
bool MeshPredictionSchemeConstrainedMultiParallelogramDecoder<
DataTypeT, TransformT, MeshDataT>::DecodePredictionData(DecoderBuffer
*buffer) {
#ifdef DRACO_BACKWARDS_COMPATIBILITY_SUPPORTED
if (buffer->bitstream_version() < DRACO_BITSTREAM_VERSION(2, 2)) {
// Decode prediction mode.
uint8_t mode;
if (!buffer->Decode(&mode)) {
return false;
}
if (mode != Mode::OPTIMAL_MULTI_PARALLELOGRAM) {
// Unsupported mode.
return false;
}
}
#endif
// Encode selected edges using separate rans bit coder for each context.
for (int i = 0; i < kMaxNumParallelograms; ++i) {
uint32_t num_flags;
DecodeVarint<uint32_t>(&num_flags, buffer);
if (num_flags > 0) {
is_crease_edge_[i].resize(num_flags);
RAnsBitDecoder decoder;
if (!decoder.StartDecoding(buffer))
return false;
for (uint32_t j = 0; j < num_flags; ++j) {
is_crease_edge_[i][j] = decoder.DecodeNextBit();
}
decoder.EndDecoding();
}
}
return MeshPredictionSchemeDecoder<DataTypeT, TransformT,
MeshDataT>::DecodePredictionData(buffer);
}
} // namespace draco
#endif // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_CONSTRAINED_MULTI_PARALLELOGRAM_DECODER_H_
|
