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123 lines
4.6 KiB
123 lines
4.6 KiB
// This file is part of libigl, a simple c++ geometry processing library.
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//
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// Copyright (C) 2016 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 "extract_non_manifold_edge_curves.h"
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#include <algorithm>
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#include <cassert>
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#include <list>
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#include <vector>
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#include <unordered_map>
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template<
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typename DerivedF,
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typename DerivedEMAP,
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typename uE2EType >
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IGL_INLINE void igl::extract_non_manifold_edge_curves(
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const Eigen::MatrixBase<DerivedF>& F,
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const Eigen::MatrixBase<DerivedEMAP>& /*EMAP*/,
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const std::vector<std::vector<uE2EType> >& uE2E,
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std::vector<std::vector<size_t> >& curves) {
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const size_t num_faces = F.rows();
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assert(F.cols() == 3);
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//typedef std::pair<size_t, size_t> Edge;
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auto edge_index_to_face_index = [&](size_t ei) { return ei % num_faces; };
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auto edge_index_to_corner_index = [&](size_t ei) { return ei / num_faces; };
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auto get_edge_end_points = [&](size_t ei, size_t& s, size_t& d) {
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const size_t fi = edge_index_to_face_index(ei);
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const size_t ci = edge_index_to_corner_index(ei);
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s = F(fi, (ci+1)%3);
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d = F(fi, (ci+2)%3);
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};
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curves.clear();
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const size_t num_unique_edges = uE2E.size();
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std::unordered_multimap<size_t, size_t> vertex_edge_adjacency;
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std::vector<size_t> non_manifold_edges;
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for (size_t i=0; i<num_unique_edges; i++) {
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const auto& adj_edges = uE2E[i];
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if (adj_edges.size() == 2) continue;
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const size_t ei = adj_edges[0];
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size_t s,d;
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get_edge_end_points(ei, s, d);
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vertex_edge_adjacency.insert({{s, i}, {d, i}});
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non_manifold_edges.push_back(i);
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assert(vertex_edge_adjacency.count(s) > 0);
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assert(vertex_edge_adjacency.count(d) > 0);
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}
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auto expand_forward = [&](std::list<size_t>& edge_curve,
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size_t& front_vertex, size_t& end_vertex) {
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while(vertex_edge_adjacency.count(front_vertex) == 2 &&
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front_vertex != end_vertex) {
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auto adj_edges = vertex_edge_adjacency.equal_range(front_vertex);
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for (auto itr = adj_edges.first; itr!=adj_edges.second; itr++) {
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const size_t uei = itr->second;
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assert(uE2E.at(uei).size() != 2);
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const size_t ei = uE2E[uei][0];
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if (uei == edge_curve.back()) continue;
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size_t s,d;
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get_edge_end_points(ei, s, d);
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edge_curve.push_back(uei);
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if (s == front_vertex) {
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front_vertex = d;
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} else if (d == front_vertex) {
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front_vertex = s;
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} else {
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throw "Invalid vertex/edge adjacency!";
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}
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break;
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}
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}
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};
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auto expand_backward = [&](std::list<size_t>& edge_curve,
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size_t& front_vertex, size_t& end_vertex) {
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while(vertex_edge_adjacency.count(front_vertex) == 2 &&
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front_vertex != end_vertex) {
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auto adj_edges = vertex_edge_adjacency.equal_range(front_vertex);
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for (auto itr = adj_edges.first; itr!=adj_edges.second; itr++) {
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const size_t uei = itr->second;
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assert(uE2E.at(uei).size() != 2);
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const size_t ei = uE2E[uei][0];
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if (uei == edge_curve.front()) continue;
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size_t s,d;
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get_edge_end_points(ei, s, d);
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edge_curve.push_front(uei);
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if (s == front_vertex) {
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front_vertex = d;
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} else if (d == front_vertex) {
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front_vertex = s;
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} else {
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throw "Invalid vertex/edge adjcency!";
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}
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break;
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}
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}
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};
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std::vector<bool> visited(num_unique_edges, false);
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for (const size_t i : non_manifold_edges) {
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if (visited[i]) continue;
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std::list<size_t> edge_curve;
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edge_curve.push_back(i);
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const auto& adj_edges = uE2E[i];
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assert(adj_edges.size() != 2);
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const size_t ei = adj_edges[0];
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size_t s,d;
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get_edge_end_points(ei, s, d);
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expand_forward(edge_curve, d, s);
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expand_backward(edge_curve, s, d);
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curves.emplace_back(edge_curve.begin(), edge_curve.end());
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for (auto itr = edge_curve.begin(); itr!=edge_curve.end(); itr++) {
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visited[*itr] = true;
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}
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}
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}
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