115 lines
3.2 KiB
C
115 lines
3.2 KiB
C
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// 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/igl_inline.h>
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// This file violates many of the libigl style guidelines.
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namespace igl
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{
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// HalfEdgeIterator - 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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//
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// Inputs:
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// F #F by 3 list of "faces"
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// FF #F by 3 list of triangle-triangle adjacency.
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// 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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// Usages:
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// FlipF/E/V changes solely one actual face/edge/vertex resp.
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// NextFE iterates through one-ring of a vertex robustly.
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//
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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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IGL_INLINE HalfEdgeIterator(
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const Eigen::PlainObjectBase<DerivedF>& _F,
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const Eigen::PlainObjectBase<DerivedFF>& _FF,
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const Eigen::PlainObjectBase<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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IGL_INLINE bool isBorder();
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/*!
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* Returns the 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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IGL_INLINE bool NextFE();
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// Get vertex index
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IGL_INLINE int Vi();
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// Get face index
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IGL_INLINE int Fi();
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// Get edge index
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IGL_INLINE int Ei();
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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::PlainObjectBase<DerivedF> & F;
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const Eigen::PlainObjectBase<DerivedFF> & FF;
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const Eigen::PlainObjectBase<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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