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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.
//
#include "draco/compression/mesh/mesh_sequential_decoder.h"
#include "draco/compression/attributes/linear_sequencer.h"
#include "draco/compression/attributes/sequential_attribute_decoders_controller.h"
#include "draco/compression/entropy/symbol_decoding.h"
#include "draco/core/varint_decoding.h"
namespace draco {
MeshSequentialDecoder::MeshSequentialDecoder() {}
bool MeshSequentialDecoder::DecodeConnectivity() {
uint32_t num_faces;
uint32_t num_points;
#ifdef DRACO_BACKWARDS_COMPATIBILITY_SUPPORTED
if (bitstream_version() < DRACO_BITSTREAM_VERSION(2, 2)) {
if (!buffer()->Decode(&num_faces)) {
return false;
}
if (!buffer()->Decode(&num_points)) {
return false;
}
} else
#endif
{
if (!DecodeVarint(&num_faces, buffer())) {
return false;
}
if (!DecodeVarint(&num_points, buffer())) {
return false;
}
}
// Check that num_faces and num_points are valid values.
const uint64_t faces_64 = static_cast<uint64_t>(num_faces);
const uint64_t points_64 = static_cast<uint64_t>(num_points);
// Compressed sequential encoding can only handle (2^32 - 1) / 3 indices.
if (faces_64 > 0xffffffff / 3) {
return false;
}
if (points_64 > faces_64 * 3) {
return false;
}
uint8_t connectivity_method;
if (!buffer()->Decode(&connectivity_method)) {
return false;
}
if (connectivity_method == 0) {
if (!DecodeAndDecompressIndices(num_faces)) {
return false;
}
} else {
if (num_points < 256) {
// Decode indices as uint8_t.
for (uint32_t i = 0; i < num_faces; ++i) {
Mesh::Face face;
for (int j = 0; j < 3; ++j) {
uint8_t val;
if (!buffer()->Decode(&val)) {
return false;
}
face[j] = val;
}
mesh()->AddFace(face);
}
} else if (num_points < (1 << 16)) {
// Decode indices as uint16_t.
for (uint32_t i = 0; i < num_faces; ++i) {
Mesh::Face face;
for (int j = 0; j < 3; ++j) {
uint16_t val;
if (!buffer()->Decode(&val)) {
return false;
}
face[j] = val;
}
mesh()->AddFace(face);
}
} else if (mesh()->num_points() < (1 << 21) &&
bitstream_version() >= DRACO_BITSTREAM_VERSION(2, 2)) {
// Decode indices as uint32_t.
for (uint32_t i = 0; i < num_faces; ++i) {
Mesh::Face face;
for (int j = 0; j < 3; ++j) {
uint32_t val;
if (!DecodeVarint(&val, buffer())) {
return false;
}
face[j] = val;
}
mesh()->AddFace(face);
}
} else {
// Decode faces as uint32_t (default).
for (uint32_t i = 0; i < num_faces; ++i) {
Mesh::Face face;
for (int j = 0; j < 3; ++j) {
uint32_t val;
if (!buffer()->Decode(&val)) {
return false;
}
face[j] = val;
}
mesh()->AddFace(face);
}
}
}
point_cloud()->set_num_points(num_points);
return true;
}
bool MeshSequentialDecoder::CreateAttributesDecoder(int32_t att_decoder_id) {
// Always create the basic attribute decoder.
return SetAttributesDecoder(
att_decoder_id,
std::unique_ptr<AttributesDecoder>(
new SequentialAttributeDecodersController(
std::unique_ptr<PointsSequencer>(
new LinearSequencer(point_cloud()->num_points())))));
}
bool MeshSequentialDecoder::DecodeAndDecompressIndices(uint32_t num_faces) {
// Get decoded indices differences that were encoded with an entropy code.
std::vector<uint32_t> indices_buffer(num_faces * 3);
if (!DecodeSymbols(num_faces * 3, 1, buffer(), indices_buffer.data())) {
return false;
}
// Reconstruct the indices from the differences.
// See MeshSequentialEncoder::CompressAndEncodeIndices() for more details.
int32_t last_index_value = 0;
int vertex_index = 0;
for (uint32_t i = 0; i < num_faces; ++i) {
Mesh::Face face;
for (int j = 0; j < 3; ++j) {
const uint32_t encoded_val = indices_buffer[vertex_index++];
int32_t index_diff = (encoded_val >> 1);
if (encoded_val & 1) {
index_diff = -index_diff;
}
const int32_t index_value = index_diff + last_index_value;
face[j] = index_value;
last_index_value = index_value;
}
mesh()->AddFace(face);
}
return true;
}
} // namespace draco
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