59 lines
1.5 KiB
C++
59 lines
1.5 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) 2015 Alec Jacobson <alecjacobson@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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#include "triangle_fan.h"
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#include "exterior_edges.h"
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#include "list_to_matrix.h"
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template <typename DerivedE, typename Derivedcap>
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IGL_INLINE void igl::triangle_fan(
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const Eigen::MatrixBase<DerivedE> & E,
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Eigen::PlainObjectBase<Derivedcap> & cap)
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{
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using namespace std;
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using namespace Eigen;
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// Handle lame base case
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if(E.size() == 0)
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{
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cap.resize(0,E.cols()+1);
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return;
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}
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// "Triangulate" aka "close" the E trivially with facets
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// Note: in 2D we need to know if E endpoints are incoming or
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// outgoing (left or right). Thus this will not work.
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assert(E.cols() == 2);
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// Arbitrary starting vertex
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//int s = E(int(((double)rand() / RAND_MAX)*E.rows()),0);
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int s = E(rand()%E.rows(),0);
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vector<vector<int> > lcap;
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for(int i = 0;i<E.rows();i++)
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{
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// Skip edges incident on s (they would be zero-area)
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if(E(i,0) == s || E(i,1) == s)
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{
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continue;
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}
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vector<int> e(3);
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e[0] = s;
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e[1] = E(i,0);
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e[2] = E(i,1);
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lcap.push_back(e);
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}
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list_to_matrix(lcap,cap);
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}
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IGL_INLINE Eigen::MatrixXi igl::triangle_fan( const Eigen::MatrixXi & E)
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{
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Eigen::MatrixXi cap;
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triangle_fan(E,cap);
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return cap;
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}
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#if IGL_STATIC_LIBRARY
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#endif
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