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extern/draco/dracoenc/src/draco/mesh/corner_table.h

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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_MESH_CORNER_TABLE_H_
#define DRACO_MESH_CORNER_TABLE_H_
#include <array>
#include <memory>
#include "draco/attributes/geometry_indices.h"
#include "draco/core/draco_index_type_vector.h"
#include "draco/core/macros.h"
#include "draco/mesh/valence_cache.h"
namespace draco {
// CornerTable is used to represent connectivity of triangular meshes.
// For every corner of all faces, the corner table stores the index of the
// opposite corner in the neighboring face (if it exists) as illustrated in the
// figure below (see corner |c| and it's opposite corner |o|).
//
// *
// /c\
// / \
// /n p\
// *-------*
// \ /
// \ /
// \o/
// *
//
// All corners are defined by unique CornerIndex and each triplet of corners
// that define a single face id always ordered consecutively as:
// { 3 * FaceIndex, 3 * FaceIndex + 1, 3 * FaceIndex +2 }.
// This representation of corners allows CornerTable to easily retrieve Next and
// Previous corners on any face (see corners |n| and |p| in the figure above).
// Using the Next, Previous, and Opposite corners then enables traversal of any
// 2-manifold surface.
// If the CornerTable is constructed from a non-manifold surface, the input
// non-manifold edges and vertices are automatically split.
class CornerTable {
public:
// TODO(hemmer): rename to Face.
// Corner table face type.
typedef std::array<VertexIndex, 3> FaceType;
CornerTable();
static std::unique_ptr<CornerTable> Create(
const IndexTypeVector<FaceIndex, FaceType> &faces);
// Initializes the CornerTable from provides set of indexed faces.
// The input faces can represent a non-manifold topology, in which case the
// non-manifold edges and vertices are going to be split.
bool Init(const IndexTypeVector<FaceIndex, FaceType> &faces);
// Resets the corner table to the given number of invalid faces.
bool Reset(int num_faces);
// Resets the corner table to the given number of invalid faces and vertices.
bool Reset(int num_faces, int num_vertices);
inline int num_vertices() const {
return static_cast<int>(vertex_corners_.size());
}
inline int num_corners() const {
return static_cast<int>(corner_to_vertex_map_.size());
}
inline int num_faces() const {
return static_cast<int>(corner_to_vertex_map_.size() / 3);
}
inline CornerIndex Opposite(CornerIndex corner) const {
if (corner == kInvalidCornerIndex)
return corner;
return opposite_corners_[corner];
}
inline CornerIndex Next(CornerIndex corner) const {
if (corner == kInvalidCornerIndex)
return corner;
return LocalIndex(++corner) ? corner : corner - 3;
}
inline CornerIndex Previous(CornerIndex corner) const {
if (corner == kInvalidCornerIndex)
return corner;
return LocalIndex(corner) ? corner - 1 : corner + 2;
}
inline VertexIndex Vertex(CornerIndex corner) const {
if (corner == kInvalidCornerIndex)
return kInvalidVertexIndex;
return ConfidentVertex(corner);
}
inline VertexIndex ConfidentVertex(CornerIndex corner) const {
DRACO_DCHECK_GE(corner.value(), 0);
DRACO_DCHECK_LT(corner.value(), num_corners());
return corner_to_vertex_map_[corner];
}
inline FaceIndex Face(CornerIndex corner) const {
if (corner == kInvalidCornerIndex)
return kInvalidFaceIndex;
return FaceIndex(corner.value() / 3);
}
inline CornerIndex FirstCorner(FaceIndex face) const {
if (face == kInvalidFaceIndex)
return kInvalidCornerIndex;
return CornerIndex(face.value() * 3);
}
inline std::array<CornerIndex, 3> AllCorners(FaceIndex face) const {
const CornerIndex ci = CornerIndex(face.value() * 3);
return {{ci, ci + 1, ci + 2}};
}
inline int LocalIndex(CornerIndex corner) const { return corner.value() % 3; }
inline FaceType FaceData(FaceIndex face) const {
const CornerIndex first_corner = FirstCorner(face);
FaceType face_data;
for (int i = 0; i < 3; ++i) {
face_data[i] = corner_to_vertex_map_[first_corner + i];
}
return face_data;
}
void SetFaceData(FaceIndex face, FaceType data) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
const CornerIndex first_corner = FirstCorner(face);
for (int i = 0; i < 3; ++i) {
corner_to_vertex_map_[first_corner + i] = data[i];
}
}
// Returns the left-most corner of a single vertex 1-ring. If a vertex is not
// on a boundary (in which case it has a full 1-ring), this function returns
// any of the corners mapped to the given vertex.
inline CornerIndex LeftMostCorner(VertexIndex v) const {
return vertex_corners_[v];
}
// Returns the parent vertex index of a given corner table vertex.
VertexIndex VertexParent(VertexIndex vertex) const {
if (vertex.value() < static_cast<uint32_t>(num_original_vertices_))
return vertex;
return non_manifold_vertex_parents_[vertex - num_original_vertices_];
}
// Returns true if the corner is valid.
inline bool IsValid(CornerIndex c) const {
return Vertex(c) != kInvalidVertexIndex;
}
// Returns the valence (or degree) of a vertex.
// Returns -1 if the given vertex index is not valid.
int Valence(VertexIndex v) const;
// Same as above but does not check for validity and does not return -1
int ConfidentValence(VertexIndex v) const;
// Returns the valence of the vertex at the given corner.
inline int Valence(CornerIndex c) const {
if (c == kInvalidCornerIndex)
return -1;
return ConfidentValence(c);
}
inline int ConfidentValence(CornerIndex c) const {
DRACO_DCHECK_LT(c.value(), num_corners());
return ConfidentValence(ConfidentVertex(c));
}
// Returns true if the specified vertex is on a boundary.
inline bool IsOnBoundary(VertexIndex vert) const {
const CornerIndex corner = LeftMostCorner(vert);
if (SwingLeft(corner) == kInvalidCornerIndex)
return true;
return false;
}
// *-------*
// / \ / \
// / \ / \
// / sl\c/sr \
// *-------v-------*
// Returns the corner on the adjacent face on the right that maps to
// the same vertex as the given corner (sr in the above diagram).
inline CornerIndex SwingRight(CornerIndex corner) const {
return Previous(Opposite(Previous(corner)));
}
// Returns the corner on the left face that maps to the same vertex as the
// given corner (sl in the above diagram).
inline CornerIndex SwingLeft(CornerIndex corner) const {
return Next(Opposite(Next(corner)));
}
// Get opposite corners on the left and right faces respectively (see image
// below, where L and R are the left and right corners of a corner X.
//
// *-------*-------*
// \L /X\ R/
// \ / \ /
// \ / \ /
// *-------*
inline CornerIndex GetLeftCorner(CornerIndex corner_id) const {
if (corner_id == kInvalidCornerIndex)
return kInvalidCornerIndex;
return Opposite(Previous(corner_id));
}
inline CornerIndex GetRightCorner(CornerIndex corner_id) const {
if (corner_id == kInvalidCornerIndex)
return kInvalidCornerIndex;
return Opposite(Next(corner_id));
}
// Returns the number of new vertices that were created as a result of
// splitting of non-manifold vertices of the input geometry.
int NumNewVertices() const { return num_vertices() - num_original_vertices_; }
int NumOriginalVertices() const { return num_original_vertices_; }
// Returns the number of faces with duplicated vertex indices.
int NumDegeneratedFaces() const { return num_degenerated_faces_; }
// Returns the number of isolated vertices (vertices that have
// vertex_corners_ mapping set to kInvalidCornerIndex.
int NumIsolatedVertices() const { return num_isolated_vertices_; }
bool IsDegenerated(FaceIndex face) const;
// Methods that modify an existing corner table.
// Sets the opposite corner mapping between two corners. Caller must ensure
// that the indices are valid.
inline void SetOppositeCorner(CornerIndex corner_id,
CornerIndex opp_corner_id) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
opposite_corners_[corner_id] = opp_corner_id;
}
// Sets opposite corners for both input corners.
inline void SetOppositeCorners(CornerIndex corner_0, CornerIndex corner_1) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
if (corner_0 != kInvalidCornerIndex)
SetOppositeCorner(corner_0, corner_1);
if (corner_1 != kInvalidCornerIndex)
SetOppositeCorner(corner_1, corner_0);
}
// Updates mapping between a corner and a vertex.
inline void MapCornerToVertex(CornerIndex corner_id, VertexIndex vert_id) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
corner_to_vertex_map_[corner_id] = vert_id;
}
VertexIndex AddNewVertex() {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
// Add a new invalid vertex.
vertex_corners_.push_back(kInvalidCornerIndex);
return VertexIndex(static_cast<uint32_t>(vertex_corners_.size() - 1));
}
// Sets a new left most corner for a given vertex.
void SetLeftMostCorner(VertexIndex vert, CornerIndex corner) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
if (vert != kInvalidVertexIndex)
vertex_corners_[vert] = corner;
}
// Updates the vertex to corner map on a specified vertex. This should be
// called in cases where the mapping may be invalid (e.g. when the corner
// table was constructed manually).
void UpdateVertexToCornerMap(VertexIndex vert) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
const CornerIndex first_c = vertex_corners_[vert];
if (first_c == kInvalidCornerIndex)
return; // Isolated vertex.
CornerIndex act_c = SwingLeft(first_c);
CornerIndex c = first_c;
while (act_c != kInvalidCornerIndex && act_c != first_c) {
c = act_c;
act_c = SwingLeft(act_c);
}
if (act_c != first_c) {
vertex_corners_[vert] = c;
}
}
// Sets the new number of vertices. It's a responsibility of the caller to
// ensure that no corner is mapped beyond the range of the new number of
// vertices.
inline void SetNumVertices(int num_vertices) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
vertex_corners_.resize(num_vertices, kInvalidCornerIndex);
}
// Makes a vertex isolated (not attached to any corner).
void MakeVertexIsolated(VertexIndex vert) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
vertex_corners_[vert] = kInvalidCornerIndex;
}
// Returns true if a vertex is not attached to any face.
inline bool IsVertexIsolated(VertexIndex v) const {
return LeftMostCorner(v) == kInvalidCornerIndex;
}
// Makes a given face invalid (all corners are marked as invalid).
void MakeFaceInvalid(FaceIndex face) {
DRACO_DCHECK(GetValenceCache().IsCacheEmpty());
if (face != kInvalidFaceIndex) {
const CornerIndex first_corner = FirstCorner(face);
for (int i = 0; i < 3; ++i) {
corner_to_vertex_map_[first_corner + i] = kInvalidVertexIndex;
}
}
}
// Updates mapping between faces and a vertex using the corners mapped to
// the provided vertex.
void UpdateFaceToVertexMap(const VertexIndex vertex);
// Allows access to an internal object for caching valences. The object can
// be instructed to cache or uncache all valences and then its interfaces
// queried directly for valences with differing performance/confidence
// qualities. If the mesh or table is modified the cache should be discarded
// and not relied on as it does not automatically update or invalidate for
// performance reasons.
const draco::ValenceCache<CornerTable> &GetValenceCache() const {
return valence_cache_;
}
private:
// Computes opposite corners mapping from the data stored in
// |corner_to_vertex_map_|. Any non-manifold edge will be split so the result
// is always a 2-manifold surface.
bool ComputeOppositeCorners(int *num_vertices);
// Computes the lookup map for going from a vertex to a corner. This method
// can handle non-manifold vertices by splitting them into multiple manifold
// vertices.
bool ComputeVertexCorners(int num_vertices);
// Each three consecutive corners represent one face.
IndexTypeVector<CornerIndex, VertexIndex> corner_to_vertex_map_;
IndexTypeVector<CornerIndex, CornerIndex> opposite_corners_;
IndexTypeVector<VertexIndex, CornerIndex> vertex_corners_;
int num_original_vertices_;
int num_degenerated_faces_;
int num_isolated_vertices_;
IndexTypeVector<VertexIndex, VertexIndex> non_manifold_vertex_parents_;
draco::ValenceCache<CornerTable> valence_cache_;
};
// A special case to denote an invalid corner table triangle.
static constexpr CornerTable::FaceType kInvalidFace(
{{kInvalidVertexIndex, kInvalidVertexIndex, kInvalidVertexIndex}});
} // namespace draco
#endif // DRACO_MESH_CORNER_TABLE_H_