| // This file is part of libigl, a simple c++ geometry processing library. | |
| // | |
| // Copyright (C) 2014 Daniele Panozzo <daniele.panozzo@gmail.com> | |
| // | |
| // This Source Code Form is subject to the terms of the Mozilla Public License | |
| // v. 2.0. If a copy of the MPL was not distributed with this file, You can | |
| // obtain one at http://mozilla.org/MPL/2.0/. | |
| // This file violates many of the libigl style guidelines. | |
| namespace igl | |
| { | |
| // HalfEdgeIterator - Fake halfedge for fast and easy navigation | |
| // on triangle meshes with vertex_triangle_adjacency and | |
| // triangle_triangle adjacency | |
| // | |
| // Note: this is different to classical Half Edge data structure. | |
| // Instead, it follows cell-tuple in [Brisson, 1989] | |
| // "Representing geometric structures in d dimensions: topology and order." | |
| // This class can achieve local navigation similar to half edge in OpenMesh | |
| // But the logic behind each atom operation is different. | |
| // So this should be more properly called TriangleTupleIterator. | |
| // | |
| // Each tuple contains information on (face, edge, vertex) | |
| // and encoded by (face, edge \in {0,1,2}, bool reverse) | |
| // | |
| // Inputs: | |
| // F #F by 3 list of "faces" | |
| // FF #F by 3 list of triangle-triangle adjacency. | |
| // FFi #F by 3 list of FF inverse. For FF and FFi, refer to | |
| // "triangle_triangle_adjacency.h" | |
| // Usages: | |
| // FlipF/E/V changes solely one actual face/edge/vertex resp. | |
| // NextFE iterates through one-ring of a vertex robustly. | |
| // | |
| template < | |
| typename DerivedF, | |
| typename DerivedFF, | |
| typename DerivedFFi> | |
| class HalfEdgeIterator | |
| { | |
| public: | |
| // Init the HalfEdgeIterator by specifying Face,Edge Index and Orientation | |
| IGL_INLINE HalfEdgeIterator( | |
| const Eigen::MatrixBase<DerivedF>& _F, | |
| const Eigen::MatrixBase<DerivedFF>& _FF, | |
| const Eigen::MatrixBase<DerivedFFi>& _FFi, | |
| int _fi, | |
| int _ei, | |
| bool _reverse = false | |
| ); | |
| // Change Face | |
| IGL_INLINE void flipF(); | |
| // Change Edge | |
| IGL_INLINE void flipE(); | |
| // Change Vertex | |
| IGL_INLINE void flipV(); | |
| IGL_INLINE bool isBorder(); | |
| /*! | |
| * Returns the next edge skipping the border | |
| * _________ | |
| * /\ c | b /\ | |
| * / \ | / \ | |
| * / d \ | / a \ | |
| * /______\|/______\ | |
| * v | |
| * In this example, if a and d are of-border and the pos is iterating | |
| counterclockwise, this method iterate through the faces incident on vertex | |
| v, | |
| * producing the sequence a, b, c, d, a, b, c, ... | |
| */ | |
| IGL_INLINE bool NextFE(); | |
| // Get vertex index | |
| IGL_INLINE int Vi(); | |
| // Get face index | |
| IGL_INLINE int Fi(); | |
| // Get edge index | |
| IGL_INLINE int Ei(); | |
| IGL_INLINE bool operator==(HalfEdgeIterator& p2); | |
| private: | |
| int fi; | |
| int ei; | |
| bool reverse; | |
| // All the same type? This is likely to break. | |
| const Eigen::MatrixBase<DerivedF> & F; | |
| const Eigen::MatrixBase<DerivedFF> & FF; | |
| const Eigen::MatrixBase<DerivedFFi> & FFi; | |
| }; | |
| } | |