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