2DFEM/ReadGmsh.cpp at master · ChrisPattison/2DFEM · GitHub

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
126
127
128
129
130
131
132
133
134
135
136
137
138
#include "ReadGmsh.hpp"

namespace Mesh
{
	void ReadGmsh(std::istream& msh, std::vector<node>& nodes, std::vector<element>& elements, std::vector<group>& groups) {
		std::string line;
		msh >> line;
		if (line.compare("$MeshFormat") == 0) {
			msh >> line;
			if (line.compare("2.2") != 0) throw std::exception("Mesh version unsupported");
			msh >> line;
			if (line[0] != '0') throw std::exception("Mesh not in ASCII Format");
			msh >> line;
			if (line[0] != '8') throw std::exception("Unexpected floating point size");
			msh >> line;
			if (line.compare("$EndMeshFormat") != 0) throw std::exception(("Expected $EndMeshFormat identifier got " + line).c_str());
		} else throw std::exception("Mesh format identifier not found");
		try {
			for (;;) {
				line = NextIdentifier(msh);
				if (line.compare("$PhysicalNames") == 0) {
					int no;
					msh >> no;
					groups.resize(no);
					for (int i = 0; i < no; ++i) {
						//msh >> line;
						//if (line == "$EndPhysicalNames" && i < no) throw std::exception("Unexpected end of PhysicalNames section");
						msh >> groups[i].Dim;
						msh >> groups[i].GmshNo;
						msh >> groups[i].Name;
						groups[i].Name = groups[i].Name.substr(1, groups[i].Name.length() - 2);
					}
				}
				if (line.compare("$Nodes") == 0) {
					int no;
					msh >> no;
					nodes.resize(no);
					double tmp;
					for (int i = 0; i < no; ++i) {
						//msh >> line;
						//if (line.compare("$EndNodes") != 0) throw std::exception("Unexpected end of Nodes section");
						msh >> nodes[i].MshNo;
						msh >> tmp;
						nodes[i].Coord(0) = tmp;
						msh >> tmp;
						nodes[i].Coord(1) = tmp;
						msh >> tmp;
					}
				}
				if (line.compare("$Elements") == 0) {
					int no;
					msh >> no;
					elements.resize(no);
					for (int i = 0; i < no; ++i) {
						//msh >> line;
						//if (line.compare("$EndElements") != 0) throw std::exception("Unexpected end of Elements section");
						msh >> elements[i].No;
						int temp, node;
						msh >> temp;
						elements[i].Type = static_cast<ELEMENT_TYPE>(temp);
						msh >> temp;
						if (temp < 1) throw std::exception("Element physical group not found.");
						msh >> elements[i].Grp;
						for (int ii = 1; ii < temp; ++ii ) {
							msh >> node;
						}
						elements[i].Grp = SearchGroup(groups, elements[i].Grp);
						switch (elements[i].Type) {
						case ELEMENT_TYPE::LINE:
							for (int ii = 0; ii < 2; ++ii) {
								msh >> node;
								elements[i].Nodes.push_back(SearchNode(nodes, node));
							}
							break;
						case ELEMENT_TYPE::TRIANGLE:
							for (int ii = 0; ii < 3; ++ii) {
								msh >> node;
								elements[i].Nodes.push_back(SearchNode(nodes, node));
							}
							break;
						}
						elements[i].Nodes.shrink_to_fit();
					}
				}
				if (msh.eof()) break;
			}
		}
		catch (std::istream::failure e) {
			if (!msh.eof()) throw e;
		}
	}

	void WriteData(std::fstream& msh, std::fstream& output, std::vector<node>& nodes, Eigen::VectorXd T) {
		output << msh.rdbuf() << "\n";
		output << "$NodeData\n1\nTemperature\n0\n3\n0\n1\n" << nodes.size() << "\n";
		for (int i = 0; i < nodes.size(); ++i)
		{
			output << nodes[i].MshNo << " " << T(i) << "\n";
		}
		output << "$EndNodeData";
	}

	std::string NextIdentifier(std::istream& msh) {
		std::string line;
		for (;;) {
			msh >> line;
			if (line[0] == '$') return line;
			if (msh.eof()) return std::string("");
		}
	}

	int SearchNode(std::vector<node>& nodes, int no) {
		for (int i = 0; i < nodes.size(); ++i) {
			if (nodes[i].MshNo == no) {
				return i;
			}
		}
		throw std::exception(("Couldn't find node: " + std::to_string(no)).c_str());
	}

	int SearchGroup(std::vector<group>& groups, int no) {
		for (int i = 0; i < groups.size(); ++i) {
			if (groups[i].GmshNo == no) {
				return i;
			}
		}
		throw std::exception(("Couldn't find group: " + std::to_string(no)).c_str());
	}

	int SearchGroup(std::vector<group>& groups, std::string name) {
		for (int i = 0; i < groups.size(); ++i) {
			if (groups[i].Name == name) {
				return i;
			}
		}
		throw std::exception(("Couldn't find group: " + name).c_str());
	}
};