File size: 4,060 Bytes
5b89cb9 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 | // This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2019 Hanxiao Shen <hanxiao@cs.nyu.edu>
//
// 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/.
#include <igl/slice.h>
#include "ear_clipping.h"
#include "point_inside_convex_polygon.h"
#include "predicates.h"
template <typename DerivedP, typename DerivedRT,
typename DerivedF, typename DerivedI>
IGL_INLINE void igl::predicates::ear_clipping(
const Eigen::MatrixBase<DerivedP>& P,
const Eigen::MatrixBase<DerivedRT>& RT,
Eigen::PlainObjectBase<DerivedI>& I,
Eigen::PlainObjectBase<DerivedF>& eF,
Eigen::PlainObjectBase<DerivedP>& nP
){
typedef typename DerivedF::Scalar Index;
typedef typename DerivedP::Scalar Scalar;
static_assert(std::is_same<typename DerivedI::Scalar,
typename DerivedF::Scalar>::value,
"index type should be consistent");
// check whether vertex i is an ear
auto is_ear = [](
const Eigen::MatrixBase<DerivedP>& P,
const Eigen::MatrixBase<DerivedRT>& RT,
const Eigen::Matrix<Index,Eigen::Dynamic,1>& L,
const Eigen::Matrix<Index,Eigen::Dynamic,1>& R,
const Index i
){
Index a = L(i), b = R(i);
if(RT(i) != 0 || RT(a) != 0 || RT(b) != 0) return false;
Eigen::Matrix<Scalar,1,2> pa = P.row(a);
Eigen::Matrix<Scalar,1,2> pb = P.row(b);
Eigen::Matrix<Scalar,1,2> pi = P.row(i);
auto r = igl::predicates::orient2d(pa,pi,pb);
if(r == igl::predicates::Orientation::NEGATIVE ||
r == igl::predicates::Orientation::COLLINEAR) return false;
// check if any vertex is lying inside triangle (a,b,i);
Index k=R(b);
while(k!=a){
Eigen::Matrix<Scalar,-1,2> T(3,2);
T<<P.row(a),P.row(i),P.row(b);
Eigen::Matrix<Scalar,1,2> q=P.row(k);
if(igl::predicates::point_inside_convex_polygon(T,q))
return false;
k=R(k);
}
return true;
};
Eigen::Matrix<Index,Eigen::Dynamic,1> L(P.rows());
Eigen::Matrix<Index,Eigen::Dynamic,1> R(P.rows());
for(int i=0;i<P.rows();i++){
L(i) = Index((i-1+P.rows())%P.rows());
R(i) = Index((i+1)%P.rows());
}
Eigen::Matrix<Index,Eigen::Dynamic,1> ears; // mark ears
Eigen::Matrix<Index,Eigen::Dynamic,1> X; // clipped vertices
ears.setZero(P.rows());
X.setZero(P.rows());
// initialize ears
for(int i=0;i<P.rows();i++){
ears(i) = is_ear(P,RT,L,R,i);
}
// clip ears until none left
while(ears.maxCoeff()==1){
// find the first ear
Index e = 0;
while(e<ears.rows()&&ears(e)!=1) e++;
// find valid neighbors
Index a = L(e), b = R(e);
if(a == b) break;
// clip ear and store face
eF.conservativeResize(eF.rows()+1,3);
eF.bottomRows(1)<<a,e,b;
L(b) = a;
L(e) = -1;
R(a) = b;
R(e) = -1;
ears(e) = 0; // mark vertex e as non-ear
// update neighbor's ear status
ears(a) = is_ear(P,RT,L,R,a);
ears(b) = is_ear(P,RT,L,R,b);
X(e) = 1;
// when only one edge left
// mark the endpoints as clipped
if(L(a)==b && R(b)==a){
X(a) = 1;
X(b) = 1;
}
}
// collect remaining vertices if theres any
for(int i=0;i<X.rows();i++)
X(i) = 1-X(i);
I.resize(X.sum());
Index j=0;
for(Index i=0;i<X.rows();i++)
if(X(i)==1){
I(j++) = i;
}
igl::slice(P,I,1,nP);
}
#ifdef IGL_STATIC_LIBRARY
template void igl::predicates::ear_clipping<Eigen::Matrix<double, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, 1, 0, -1, 1>, Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, 1, 0, -1, 1> >(Eigen::MatrixBase<Eigen::Matrix<double, -1, -1, 0, -1, -1> > const&, Eigen::MatrixBase<Eigen::Matrix<int, -1, 1, 0, -1, 1> > const&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, 1, 0, -1, 1> >&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> >&, Eigen::PlainObjectBase<Eigen::Matrix<double, -1, -1, 0, -1, -1> >&);
#endif
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