1 // Copyright 2016 The Draco Authors. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 #ifndef DRACO_MESH_CORNER_TABLE_H_ 16 #define DRACO_MESH_CORNER_TABLE_H_ 17 18 #include <array> 19 #include <memory> 20 21 #include "draco/attributes/geometry_indices.h" 22 #include "draco/core/draco_index_type_vector.h" 23 #include "draco/core/macros.h" 24 #include "draco/mesh/valence_cache.h" 25 26 namespace draco { 27 28 // CornerTable is used to represent connectivity of triangular meshes. 29 // For every corner of all faces, the corner table stores the index of the 30 // opposite corner in the neighboring face (if it exists) as illustrated in the 31 // figure below (see corner |c| and it's opposite corner |o|). 32 // 33 // * 34 // /c\ 35 // / \ 36 // /n p\ 37 // *-------* 38 // \ / 39 // \ / 40 // \o/ 41 // * 42 // 43 // All corners are defined by unique CornerIndex and each triplet of corners 44 // that define a single face id always ordered consecutively as: 45 // { 3 * FaceIndex, 3 * FaceIndex + 1, 3 * FaceIndex +2 }. 46 // This representation of corners allows CornerTable to easily retrieve Next and 47 // Previous corners on any face (see corners |n| and |p| in the figure above). 48 // Using the Next, Previous, and Opposite corners then enables traversal of any 49 // 2-manifold surface. 50 // If the CornerTable is constructed from a non-manifold surface, the input 51 // non-manifold edges and vertices are automatically split. 52 class CornerTable { 53 public: 54 // Corner table face type. 55 typedef std::array<VertexIndex, 3> FaceType; 56 57 CornerTable(); 58 static std::unique_ptr<CornerTable> Create( 59 const IndexTypeVector<FaceIndex, FaceType> &faces); 60 61 // Initializes the CornerTable from provides set of indexed faces. 62 // The input faces can represent a non-manifold topology, in which case the 63 // non-manifold edges and vertices are going to be split. 64 bool Init(const IndexTypeVector<FaceIndex, FaceType> &faces); 65 66 // Resets the corner table to the given number of invalid faces. 67 bool Reset(int num_faces); 68 69 // Resets the corner table to the given number of invalid faces and vertices. 70 bool Reset(int num_faces, int num_vertices); 71 num_vertices()72 inline int num_vertices() const { 73 return static_cast<int>(vertex_corners_.size()); 74 } num_corners()75 inline int num_corners() const { 76 return static_cast<int>(corner_to_vertex_map_.size()); 77 } num_faces()78 inline int num_faces() const { 79 return static_cast<int>(corner_to_vertex_map_.size() / 3); 80 } 81 Opposite(CornerIndex corner)82 inline CornerIndex Opposite(CornerIndex corner) const { 83 if (corner == kInvalidCornerIndex) 84 return corner; 85 return opposite_corners_[corner]; 86 } Next(CornerIndex corner)87 inline CornerIndex Next(CornerIndex corner) const { 88 if (corner == kInvalidCornerIndex) 89 return corner; 90 return LocalIndex(++corner) ? corner : corner - 3; 91 } Previous(CornerIndex corner)92 inline CornerIndex Previous(CornerIndex corner) const { 93 if (corner == kInvalidCornerIndex) 94 return corner; 95 return LocalIndex(corner) ? corner - 1 : corner + 2; 96 } Vertex(CornerIndex corner)97 inline VertexIndex Vertex(CornerIndex corner) const { 98 if (corner == kInvalidCornerIndex) 99 return kInvalidVertexIndex; 100 return ConfidentVertex(corner); 101 } ConfidentVertex(CornerIndex corner)102 inline VertexIndex ConfidentVertex(CornerIndex corner) const { 103 DRACO_DCHECK_GE(corner.value(), 0); 104 DRACO_DCHECK_LT(corner.value(), num_corners()); 105 return corner_to_vertex_map_[corner]; 106 } Face(CornerIndex corner)107 inline FaceIndex Face(CornerIndex corner) const { 108 if (corner == kInvalidCornerIndex) 109 return kInvalidFaceIndex; 110 return FaceIndex(corner.value() / 3); 111 } FirstCorner(FaceIndex face)112 inline CornerIndex FirstCorner(FaceIndex face) const { 113 if (face == kInvalidFaceIndex) 114 return kInvalidCornerIndex; 115 return CornerIndex(face.value() * 3); 116 } AllCorners(FaceIndex face)117 inline std::array<CornerIndex, 3> AllCorners(FaceIndex face) const { 118 const CornerIndex ci = CornerIndex(face.value() * 3); 119 return {{ci, ci + 1, ci + 2}}; 120 } LocalIndex(CornerIndex corner)121 inline int LocalIndex(CornerIndex corner) const { return corner.value() % 3; } 122 FaceData(FaceIndex face)123 inline FaceType FaceData(FaceIndex face) const { 124 const CornerIndex first_corner = FirstCorner(face); 125 FaceType face_data; 126 for (int i = 0; i < 3; ++i) { 127 face_data[i] = corner_to_vertex_map_[first_corner + i]; 128 } 129 return face_data; 130 } 131 SetFaceData(FaceIndex face,FaceType data)132 void SetFaceData(FaceIndex face, FaceType data) { 133 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 134 const CornerIndex first_corner = FirstCorner(face); 135 for (int i = 0; i < 3; ++i) { 136 corner_to_vertex_map_[first_corner + i] = data[i]; 137 } 138 } 139 140 // Returns the left-most corner of a single vertex 1-ring. If a vertex is not 141 // on a boundary (in which case it has a full 1-ring), this function returns 142 // any of the corners mapped to the given vertex. LeftMostCorner(VertexIndex v)143 inline CornerIndex LeftMostCorner(VertexIndex v) const { 144 return vertex_corners_[v]; 145 } 146 147 // Returns the parent vertex index of a given corner table vertex. VertexParent(VertexIndex vertex)148 VertexIndex VertexParent(VertexIndex vertex) const { 149 if (vertex.value() < static_cast<uint32_t>(num_original_vertices_)) 150 return vertex; 151 return non_manifold_vertex_parents_[vertex - num_original_vertices_]; 152 } 153 154 // Returns true if the corner is valid. IsValid(CornerIndex c)155 inline bool IsValid(CornerIndex c) const { 156 return Vertex(c) != kInvalidVertexIndex; 157 } 158 159 // Returns the valence (or degree) of a vertex. 160 // Returns -1 if the given vertex index is not valid. 161 int Valence(VertexIndex v) const; 162 // Same as above but does not check for validity and does not return -1 163 int ConfidentValence(VertexIndex v) const; 164 // Returns the valence of the vertex at the given corner. Valence(CornerIndex c)165 inline int Valence(CornerIndex c) const { 166 if (c == kInvalidCornerIndex) 167 return -1; 168 return ConfidentValence(c); 169 } ConfidentValence(CornerIndex c)170 inline int ConfidentValence(CornerIndex c) const { 171 DRACO_DCHECK_LT(c.value(), num_corners()); 172 return ConfidentValence(ConfidentVertex(c)); 173 } 174 175 // Returns true if the specified vertex is on a boundary. IsOnBoundary(VertexIndex vert)176 inline bool IsOnBoundary(VertexIndex vert) const { 177 const CornerIndex corner = LeftMostCorner(vert); 178 if (SwingLeft(corner) == kInvalidCornerIndex) 179 return true; 180 return false; 181 } 182 183 // *-------* 184 // / \ / \ 185 // / \ / \ 186 // / sl\c/sr \ 187 // *-------v-------* 188 // Returns the corner on the adjacent face on the right that maps to 189 // the same vertex as the given corner (sr in the above diagram). SwingRight(CornerIndex corner)190 inline CornerIndex SwingRight(CornerIndex corner) const { 191 return Previous(Opposite(Previous(corner))); 192 } 193 // Returns the corner on the left face that maps to the same vertex as the 194 // given corner (sl in the above diagram). SwingLeft(CornerIndex corner)195 inline CornerIndex SwingLeft(CornerIndex corner) const { 196 return Next(Opposite(Next(corner))); 197 } 198 199 // Get opposite corners on the left and right faces respectively (see image 200 // below, where L and R are the left and right corners of a corner X. 201 // 202 // *-------*-------* 203 // \L /X\ R/ 204 // \ / \ / 205 // \ / \ / 206 // *-------* GetLeftCorner(CornerIndex corner_id)207 inline CornerIndex GetLeftCorner(CornerIndex corner_id) const { 208 if (corner_id == kInvalidCornerIndex) 209 return kInvalidCornerIndex; 210 return Opposite(Previous(corner_id)); 211 } GetRightCorner(CornerIndex corner_id)212 inline CornerIndex GetRightCorner(CornerIndex corner_id) const { 213 if (corner_id == kInvalidCornerIndex) 214 return kInvalidCornerIndex; 215 return Opposite(Next(corner_id)); 216 } 217 218 // Returns the number of new vertices that were created as a result of 219 // splitting of non-manifold vertices of the input geometry. NumNewVertices()220 int NumNewVertices() const { return num_vertices() - num_original_vertices_; } NumOriginalVertices()221 int NumOriginalVertices() const { return num_original_vertices_; } 222 223 // Returns the number of faces with duplicated vertex indices. NumDegeneratedFaces()224 int NumDegeneratedFaces() const { return num_degenerated_faces_; } 225 226 // Returns the number of isolated vertices (vertices that have 227 // vertex_corners_ mapping set to kInvalidCornerIndex. NumIsolatedVertices()228 int NumIsolatedVertices() const { return num_isolated_vertices_; } 229 230 bool IsDegenerated(FaceIndex face) const; 231 232 // Methods that modify an existing corner table. 233 // Sets the opposite corner mapping between two corners. Caller must ensure 234 // that the indices are valid. SetOppositeCorner(CornerIndex corner_id,CornerIndex opp_corner_id)235 inline void SetOppositeCorner(CornerIndex corner_id, 236 CornerIndex opp_corner_id) { 237 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 238 opposite_corners_[corner_id] = opp_corner_id; 239 } 240 241 // Sets opposite corners for both input corners. SetOppositeCorners(CornerIndex corner_0,CornerIndex corner_1)242 inline void SetOppositeCorners(CornerIndex corner_0, CornerIndex corner_1) { 243 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 244 if (corner_0 != kInvalidCornerIndex) 245 SetOppositeCorner(corner_0, corner_1); 246 if (corner_1 != kInvalidCornerIndex) 247 SetOppositeCorner(corner_1, corner_0); 248 } 249 250 // Updates mapping between a corner and a vertex. MapCornerToVertex(CornerIndex corner_id,VertexIndex vert_id)251 inline void MapCornerToVertex(CornerIndex corner_id, VertexIndex vert_id) { 252 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 253 corner_to_vertex_map_[corner_id] = vert_id; 254 } 255 AddNewVertex()256 VertexIndex AddNewVertex() { 257 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 258 // Add a new invalid vertex. 259 vertex_corners_.push_back(kInvalidCornerIndex); 260 return VertexIndex(static_cast<uint32_t>(vertex_corners_.size() - 1)); 261 } 262 263 // Sets a new left most corner for a given vertex. SetLeftMostCorner(VertexIndex vert,CornerIndex corner)264 void SetLeftMostCorner(VertexIndex vert, CornerIndex corner) { 265 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 266 if (vert != kInvalidVertexIndex) 267 vertex_corners_[vert] = corner; 268 } 269 270 // Updates the vertex to corner map on a specified vertex. This should be 271 // called in cases where the mapping may be invalid (e.g. when the corner 272 // table was constructed manually). UpdateVertexToCornerMap(VertexIndex vert)273 void UpdateVertexToCornerMap(VertexIndex vert) { 274 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 275 const CornerIndex first_c = vertex_corners_[vert]; 276 if (first_c == kInvalidCornerIndex) 277 return; // Isolated vertex. 278 CornerIndex act_c = SwingLeft(first_c); 279 CornerIndex c = first_c; 280 while (act_c != kInvalidCornerIndex && act_c != first_c) { 281 c = act_c; 282 act_c = SwingLeft(act_c); 283 } 284 if (act_c != first_c) { 285 vertex_corners_[vert] = c; 286 } 287 } 288 289 // Sets the new number of vertices. It's a responsibility of the caller to 290 // ensure that no corner is mapped beyond the range of the new number of 291 // vertices. SetNumVertices(int num_vertices)292 inline void SetNumVertices(int num_vertices) { 293 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 294 vertex_corners_.resize(num_vertices, kInvalidCornerIndex); 295 } 296 297 // Makes a vertex isolated (not attached to any corner). MakeVertexIsolated(VertexIndex vert)298 void MakeVertexIsolated(VertexIndex vert) { 299 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 300 vertex_corners_[vert] = kInvalidCornerIndex; 301 } 302 303 // Returns true if a vertex is not attached to any face. IsVertexIsolated(VertexIndex v)304 inline bool IsVertexIsolated(VertexIndex v) const { 305 return LeftMostCorner(v) == kInvalidCornerIndex; 306 } 307 308 // Makes a given face invalid (all corners are marked as invalid). MakeFaceInvalid(FaceIndex face)309 void MakeFaceInvalid(FaceIndex face) { 310 DRACO_DCHECK(GetValenceCache().IsCacheEmpty()); 311 if (face != kInvalidFaceIndex) { 312 const CornerIndex first_corner = FirstCorner(face); 313 for (int i = 0; i < 3; ++i) { 314 corner_to_vertex_map_[first_corner + i] = kInvalidVertexIndex; 315 } 316 } 317 } 318 319 // Updates mapping between faces and a vertex using the corners mapped to 320 // the provided vertex. 321 void UpdateFaceToVertexMap(const VertexIndex vertex); 322 323 // Allows access to an internal object for caching valences. The object can 324 // be instructed to cache or uncache all valences and then its interfaces 325 // queried directly for valences with differing performance/confidence 326 // qualities. If the mesh or table is modified the cache should be discarded 327 // and not relied on as it does not automatically update or invalidate for 328 // performance reasons. GetValenceCache()329 const draco::ValenceCache<CornerTable> &GetValenceCache() const { 330 return valence_cache_; 331 } 332 333 private: 334 // Computes opposite corners mapping from the data stored in 335 // |corner_to_vertex_map_|. 336 bool ComputeOppositeCorners(int *num_vertices); 337 338 // Finds and breaks non-manifold edges in the 1-ring neighborhood around 339 // vertices (vertices themselves will be split in the ComputeVertexCorners() 340 // function if necessary). 341 bool BreakNonManifoldEdges(); 342 343 // Computes the lookup map for going from a vertex to a corner. This method 344 // can handle non-manifold vertices by splitting them into multiple manifold 345 // vertices. 346 bool ComputeVertexCorners(int num_vertices); 347 348 // Each three consecutive corners represent one face. 349 IndexTypeVector<CornerIndex, VertexIndex> corner_to_vertex_map_; 350 IndexTypeVector<CornerIndex, CornerIndex> opposite_corners_; 351 IndexTypeVector<VertexIndex, CornerIndex> vertex_corners_; 352 353 int num_original_vertices_; 354 int num_degenerated_faces_; 355 int num_isolated_vertices_; 356 IndexTypeVector<VertexIndex, VertexIndex> non_manifold_vertex_parents_; 357 358 draco::ValenceCache<CornerTable> valence_cache_; 359 }; 360 361 // A special case to denote an invalid corner table triangle. 362 static constexpr CornerTable::FaceType kInvalidFace( 363 {{kInvalidVertexIndex, kInvalidVertexIndex, kInvalidVertexIndex}}); 364 365 } // namespace draco 366 367 #endif // DRACO_MESH_CORNER_TABLE_H_ 368