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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_MESH_MESH_EDGEBREAKER_TRAVERSAL_DECODER_H_
#define DRACO_COMPRESSION_MESH_MESH_EDGEBREAKER_TRAVERSAL_DECODER_H_
#include "draco/compression/bit_coders/rans_bit_decoder.h"
#include "draco/compression/mesh/mesh_edgebreaker_decoder.h"
#include "draco/compression/mesh/mesh_edgebreaker_decoder_impl_interface.h"
#include "draco/compression/mesh/mesh_edgebreaker_shared.h"
#include "draco/draco_features.h"
namespace draco {
typedef RAnsBitDecoder BinaryDecoder;
// Default implementation of the edgebreaker traversal decoder that reads the
// traversal data directly from a buffer.
class MeshEdgebreakerTraversalDecoder {
public:
MeshEdgebreakerTraversalDecoder()
: attribute_connectivity_decoders_(nullptr),
num_attribute_data_(0),
decoder_impl_(nullptr) {}
void Init(MeshEdgebreakerDecoderImplInterface *decoder) {
decoder_impl_ = decoder;
buffer_.Init(decoder->GetDecoder()->buffer()->data_head(),
decoder->GetDecoder()->buffer()->remaining_size(),
decoder->GetDecoder()->buffer()->bitstream_version());
}
// Returns the Draco bitstream version.
uint16_t BitstreamVersion() const {
return decoder_impl_->GetDecoder()->bitstream_version();
}
// Used to tell the decoder what is the number of expected decoded vertices.
// Ignored by default.
void SetNumEncodedVertices(int /* num_vertices */) {}
// Set the number of non-position attribute data for which we need to decode
// the connectivity.
void SetNumAttributeData(int num_data) { num_attribute_data_ = num_data; }
// Called before the traversal decoding is started.
// Returns a buffer decoder that points to data that was encoded after the
// traversal.
bool Start(DecoderBuffer *out_buffer) {
// Decode symbols from the main buffer decoder and face configurations from
// the start_face_buffer decoder.
if (!DecodeTraversalSymbols()) {
return false;
}
if (!DecodeStartFaces()) {
return false;
}
if (!DecodeAttributeSeams()) {
return false;
}
*out_buffer = buffer_;
return true;
}
// Returns the configuration of a new initial face.
inline bool DecodeStartFaceConfiguration() {
uint32_t face_configuration;
#ifdef DRACO_BACKWARDS_COMPATIBILITY_SUPPORTED
if (buffer_.bitstream_version() < DRACO_BITSTREAM_VERSION(2, 2)) {
start_face_buffer_.DecodeLeastSignificantBits32(1, &face_configuration);
} else
#endif
{
face_configuration = start_face_decoder_.DecodeNextBit();
}
return face_configuration;
}
// Returns the next edgebreaker symbol that was reached during the traversal.
inline uint32_t DecodeSymbol() {
uint32_t symbol;
symbol_buffer_.DecodeLeastSignificantBits32(1, &symbol);
if (symbol == TOPOLOGY_C) {
return symbol;
}
// Else decode two additional bits.
uint32_t symbol_suffix;
symbol_buffer_.DecodeLeastSignificantBits32(2, &symbol_suffix);
symbol |= (symbol_suffix << 1);
return symbol;
}
// Called whenever a new active corner is set in the decoder.
inline void NewActiveCornerReached(CornerIndex /* corner */) {}
// Called whenever |source| vertex is about to be merged into the |dest|
// vertex.
inline void MergeVertices(VertexIndex /* dest */, VertexIndex /* source */) {}
// Returns true if there is an attribute seam for the next processed pair
// of visited faces.
// |attribute| is used to mark the id of the non-position attribute (in range
// of <0, num_attributes - 1>).
inline bool DecodeAttributeSeam(int attribute) {
return attribute_connectivity_decoders_[attribute].DecodeNextBit();
}
// Called when the traversal is finished.
void Done() {
if (symbol_buffer_.bit_decoder_active()) {
symbol_buffer_.EndBitDecoding();
}
#ifdef DRACO_BACKWARDS_COMPATIBILITY_SUPPORTED
if (buffer_.bitstream_version() < DRACO_BITSTREAM_VERSION(2, 2)) {
start_face_buffer_.EndBitDecoding();
} else
#endif
{
start_face_decoder_.EndDecoding();
}
}
protected:
DecoderBuffer *buffer() { return &buffer_; }
bool DecodeTraversalSymbols() {
uint64_t traversal_size;
symbol_buffer_ = buffer_;
if (!symbol_buffer_.StartBitDecoding(true, &traversal_size)) {
return false;
}
buffer_ = symbol_buffer_;
if (traversal_size > static_cast<uint64_t>(buffer_.remaining_size())) {
return false;
}
buffer_.Advance(traversal_size);
return true;
}
bool DecodeStartFaces() {
// Create a decoder that is set to the end of the encoded traversal data.
#ifdef DRACO_BACKWARDS_COMPATIBILITY_SUPPORTED
if (buffer_.bitstream_version() < DRACO_BITSTREAM_VERSION(2, 2)) {
start_face_buffer_ = buffer_;
uint64_t traversal_size;
if (!start_face_buffer_.StartBitDecoding(true, &traversal_size)) {
return false;
}
buffer_ = start_face_buffer_;
if (traversal_size > static_cast<uint64_t>(buffer_.remaining_size())) {
return false;
}
buffer_.Advance(traversal_size);
return true;
}
#endif
return start_face_decoder_.StartDecoding(&buffer_);
}
bool DecodeAttributeSeams() {
// Prepare attribute decoding.
if (num_attribute_data_ > 0) {
attribute_connectivity_decoders_ = std::unique_ptr<BinaryDecoder[]>(
new BinaryDecoder[num_attribute_data_]);
for (int i = 0; i < num_attribute_data_; ++i) {
if (!attribute_connectivity_decoders_[i].StartDecoding(&buffer_)) {
return false;
}
}
}
return true;
}
private:
// Buffer that contains the encoded data.
DecoderBuffer buffer_;
DecoderBuffer symbol_buffer_;
BinaryDecoder start_face_decoder_;
DecoderBuffer start_face_buffer_;
std::unique_ptr<BinaryDecoder[]> attribute_connectivity_decoders_;
int num_attribute_data_;
const MeshEdgebreakerDecoderImplInterface *decoder_impl_;
};
} // namespace draco
#endif // DRACO_COMPRESSION_MESH_MESH_EDGEBREAKER_TRAVERSAL_DECODER_H_
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