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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_ENCODER_IMPL_H_
+#define DRACO_COMPRESSION_MESH_MESH_EDGEBREAKER_ENCODER_IMPL_H_
+
+#include <unordered_map>
+
+#include "draco/compression/attributes/mesh_attribute_indices_encoding_data.h"
+#include "draco/compression/config/compression_shared.h"
+#include "draco/compression/mesh/mesh_edgebreaker_encoder_impl_interface.h"
+#include "draco/compression/mesh/mesh_edgebreaker_shared.h"
+#include "draco/compression/mesh/traverser/mesh_traversal_sequencer.h"
+#include "draco/core/encoder_buffer.h"
+#include "draco/mesh/mesh_attribute_corner_table.h"
+
+namespace draco {
+
+// Class implementing the edgebreaker encoding as described in "3D Compression
+// Made Simple: Edgebreaker on a Corner-Table" by Rossignac at al.'01.
+// http://www.cc.gatech.edu/~jarek/papers/CornerTableSMI.pdf
+template <class TraversalEncoderT>
+class MeshEdgebreakerEncoderImpl : public MeshEdgebreakerEncoderImplInterface {
+ public:
+  MeshEdgebreakerEncoderImpl();
+  explicit MeshEdgebreakerEncoderImpl(
+      const TraversalEncoderT &traversal_encoder);
+  bool Init(MeshEdgebreakerEncoder *encoder) override;
+
+  const MeshAttributeCornerTable *GetAttributeCornerTable(
+      int att_id) const override;
+  const MeshAttributeIndicesEncodingData *GetAttributeEncodingData(
+      int att_id) const override;
+
+  bool GenerateAttributesEncoder(int32_t att_id) override;
+  bool EncodeAttributesEncoderIdentifier(int32_t att_encoder_id) override;
+  Status EncodeConnectivity() override;
+
+  const CornerTable *GetCornerTable() const override {
+    return corner_table_.get();
+  }
+  bool IsFaceEncoded(FaceIndex fi) const override {
+    return visited_faces_[fi.value()];
+  }
+  MeshEdgebreakerEncoder *GetEncoder() const override { return encoder_; }
+
+ private:
+  // Initializes data needed for encoding non-position attributes.
+  // Returns false on error.
+  bool InitAttributeData();
+
+  // Creates a vertex traversal sequencer for the specified |TraverserT| type.
+  template <class TraverserT>
+  std::unique_ptr<PointsSequencer> CreateVertexTraversalSequencer(
+      MeshAttributeIndicesEncodingData *encoding_data);
+
+  // Finds the configuration of the initial face that starts the traversal.
+  // Configurations are determined by location of holes around the init face
+  // and they are described in mesh_edgebreaker_shared.h.
+  // Returns true if the face configuration is interior and false if it is
+  // exterior.
+  bool FindInitFaceConfiguration(FaceIndex face_id,
+                                 CornerIndex *out_corner_id) const;
+
+  // Encodes the connectivity between vertices.
+  bool EncodeConnectivityFromCorner(CornerIndex corner_id);
+
+  // Encodes all vertices of a hole starting at start_corner_id.
+  // The vertex associated with the first corner is encoded only if
+  // |encode_first_vertex| is true.
+  // Returns the number of encoded hole vertices.
+  int EncodeHole(CornerIndex start_corner_id, bool encode_first_vertex);
+
+  // Encodes topology split data.
+  // Returns nullptr on error.
+  bool EncodeSplitData();
+
+  CornerIndex GetRightCorner(CornerIndex corner_id) const;
+  CornerIndex GetLeftCorner(CornerIndex corner_id) const;
+
+  bool IsRightFaceVisited(CornerIndex corner_id) const;
+  bool IsLeftFaceVisited(CornerIndex corner_id) const;
+  bool IsVertexVisited(VertexIndex vert_id) const {
+    return visited_vertex_ids_[vert_id.value()];
+  }
+
+  // Finds and stores data about all holes in the input mesh.
+  bool FindHoles();
+
+  // For faces encoded with symbol TOPOLOGY_S (split), this method returns
+  // the encoded symbol id or -1 if the face wasn't encoded by a split symbol.
+  int GetSplitSymbolIdOnFace(int face_id) const;
+
+  // Checks whether there is a topology split event on a neighboring face and
+  // stores the event data if necessary. For more info about topology split
+  // events, see description of TopologySplitEventData in
+  // mesh_edgebreaker_shared.h.
+  void CheckAndStoreTopologySplitEvent(int src_symbol_id, int src_face_id,
+                                       EdgeFaceName src_edge,
+                                       int neighbor_face_id);
+
+  // Encodes connectivity of all attributes on a newly traversed face.
+  bool EncodeAttributeConnectivitiesOnFace(CornerIndex corner);
+
+  // This function is used to to assign correct encoding order of attributes
+  // to unprocessed corners. The encoding order is equal to the order in which
+  // the attributes are going to be processed by the decoder and it is necessary
+  // for proper prediction of attribute values.
+  bool AssignPositionEncodingOrderToAllCorners();
+
+  // This function is used to generate encoding order for all non-position
+  // attributes.
+  // Returns false when one or more attributes failed to be processed.
+  bool GenerateEncodingOrderForAttributes();
+
+  // The main encoder that owns this class.
+  MeshEdgebreakerEncoder *encoder_;
+  // Mesh that's being encoded.
+  const Mesh *mesh_;
+  // Corner table stores the mesh face connectivity data.
+  std::unique_ptr<CornerTable> corner_table_;
+  // Stack used for storing corners that need to be traversed when encoding
+  // the connectivity. New corner is added for each initial face and a split
+  // symbol, and one corner is removed when the end symbol is reached.
+  // Stored as member variable to prevent frequent memory reallocations when
+  // handling meshes with lots of disjoint components. Originally, we used
+  // recursive functions to handle this behavior, but that can cause stack
+  // memory overflow when compressing huge meshes.
+  std::vector<CornerIndex> corner_traversal_stack_;
+  // Array for marking visited faces.
+  std::vector<bool> visited_faces_;
+
+  // Attribute data for position encoding.
+  MeshAttributeIndicesEncodingData pos_encoding_data_;
+
+  // Traversal method used for the position attribute.
+  MeshTraversalMethod pos_traversal_method_;
+
+  // Array storing corners in the order they were visited during the
+  // connectivity encoding (always storing the tip corner of each newly visited
+  // face).
+  std::vector<CornerIndex> processed_connectivity_corners_;
+
+  // Array for storing visited vertex ids of all input vertices.
+  std::vector<bool> visited_vertex_ids_;
+
+  // For each traversal, this array stores the number of visited vertices.
+  std::vector<int> vertex_traversal_length_;
+  // Array for storing all topology split events encountered during the mesh
+  // traversal.
+  std::vector<TopologySplitEventData> topology_split_event_data_;
+  // Map between face_id and symbol_id. Contains entries only for faces that
+  // were encoded with TOPOLOGY_S symbol.
+  std::unordered_map<int, int> face_to_split_symbol_map_;
+
+  // Array for marking holes that has been reached during the traversal.
+  std::vector<bool> visited_holes_;
+  // Array for mapping vertices to hole ids. If a vertex is not on a hole, the
+  // stored value is -1.
+  std::vector<int> vertex_hole_id_;
+
+  // Id of the last encoded symbol.
+  int last_encoded_symbol_id_;
+
+  // The number of encoded split symbols.
+  uint32_t num_split_symbols_;
+
+  // Struct holding data used for encoding each non-position attribute.
+  // TODO(ostava): This should be probably renamed to something better.
+  struct AttributeData {
+    AttributeData() : attribute_index(-1), is_connectivity_used(true) {}
+    int attribute_index;
+    MeshAttributeCornerTable connectivity_data;
+    // Flag that can mark the connectivity_data invalid. In such case the base
+    // corner table of the mesh should be used instead.
+    bool is_connectivity_used;
+    // Data about attribute encoding order.
+    MeshAttributeIndicesEncodingData encoding_data;
+    // Traversal method used to generate the encoding data for this attribute.
+    MeshTraversalMethod traversal_method;
+  };
+  std::vector<AttributeData> attribute_data_;
+
+  // Array storing mapping between attribute encoder id and attribute data id.
+  std::vector<int32_t> attribute_encoder_to_data_id_map_;
+
+  TraversalEncoderT traversal_encoder_;
+
+  // If set, the encoder is going to use the same connectivity for all
+  // attributes. This effectively breaks the mesh along all attribute seams.
+  // In general, this approach should be much faster compared to encoding each
+  // connectivity separately, but the decoded model may contain higher number of
+  // duplicate attribute values which may decrease the compression ratio.
+  bool use_single_connectivity_;
+};
+
+}  // namespace draco
+
+#endif  // DRACO_COMPRESSION_MESH_MESH_EDGEBREAKER_ENCODER_IMPL_H_