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Mesh Oriented datABase
(version 5.5.1)
An array-based unstructured mesh library
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Mesh Oriented datABase
(version 5.5.1)
An array-based unstructured mesh library
|
beginner tutorial, example 2: Demonstrates loading a mesh from a file, finding coordinate locations, connectivity information... More...
Include dependency graph for mbex2.cpp:Go to the source code of this file.
Functions | |
| int | main () |
beginner tutorial, example 2: Demonstrates loading a mesh from a file, finding coordinate locations, connectivity information...
In this example, we read in the VTK file (mbex1.vtk) generated in example 1, pick one of the hexahedrons, find out the vertexes that define it (connectivity), and find the coordinates of those vertexes. Finally, we will rotate the mesh a little and write it out to a new file.
Definition in file mbex2.cpp.
| int main | ( | ) |
Definition at line 27 of file mbex2.cpp.
28 {
29 moab::ErrorCode rval;
30 moab::Core mbcore;
31 moab::Interface& mbint = mbcore;
32
33 // First, lets load the file from the previous example. Note that
34 // you must compile and run the previous example to get mbex1.vtk!
35 rval = mbint.load_file( "mbex1.vtk" );MB_CHK_SET_ERR( rval, "load_file failed" );
36
37 // *********************
38 // * Introspection *
39 // *********************
40
41 // We can now access everything about the mesh through mbint. Lets
42 // pick an element and find some information about it. In this case,
43 // we know that all of the elements in the mesh are hexahedrons, so
44 // we will ask MOAB for a range containing the handle for all hexes:
45 moab::Range hex_range;
46 rval = mbint.get_entities_by_type( 0, moab::MBHEX, hex_range );MB_CHK_SET_ERR( rval, "get_entities_by_type(HEX) failed" );
47
48 std::cout << "Loaded a mesh containing: " << hex_range << std::endl;
49
50 // Let's analyze one of the hexes (in this case, I picked hex three):
51 moab::EntityHandle handle = hex_range[3];
52
53 // Find out the eight vertexes that define this particular hex:
54 moab::Range connectivity;
55 rval = mbint.get_connectivity( &handle, 1, connectivity );MB_CHK_SET_ERR( rval, "get_connectivity failed" );
56
57 // Connectivity should now contain the handles for the eight
58 // vertexes of interest. Lets print the handle and coordinate of
59 // each vertex. Note how we iterate through the range just like with
60 // STL containers...
61 double coord[3];
62 moab::Range::iterator iter;
63
64 std::cout << std::setw( 6 ) << "Handle" << std::setw( 10 ) << "X" << std::setw( 10 ) << "Y" << std::setw( 10 )
65 << "Z" << std::endl;
66
67 for( iter = connectivity.begin(); iter != connectivity.end(); ++iter )
68 {
69 rval = mbint.get_coords( &( *iter ), 1, coord );MB_CHK_SET_ERR( rval, "get_coords" );
70
71 // Print the entity handle followed by the x, y, z coordinate of
72 // the vertex:
73 std::cout << std::setw( 6 ) << *iter << std::setw( 10 ) << coord[0] << std::setw( 10 ) << coord[1]
74 << std::setw( 10 ) << coord[2] << std::endl;
75 }
76
77 // ***********************
78 // * Rotate the Mesh *
79 // ***********************
80
81 // Now, let's rotate the mesh about the z-axis by pi/4 radians. Do
82 // to this, we will iterate through all of the vertexes
83
84 // Start by getting a range containing all of the vertex handles:
85 moab::Range vertex_range;
86 rval = mbint.get_entities_by_type( 0, moab::MBVERTEX, vertex_range );MB_CHK_SET_ERR( rval, "get_entities_by_type(VERTEX) failed" );
87
88 // Get the coordinates of all of the vertexes:
89 std::vector< double > vertex_coords( 3 * vertex_range.size() );
90 rval = mbint.get_coords( vertex_range, vertex_coords.data() );MB_CHK_SET_ERR( rval, "get_coords" );
91
92 unsigned count = 0;
93 const double PI = 3.14159265359;
94 const double ANGLE = PI / 4;
95 for( iter = vertex_range.begin(); iter != vertex_range.end(); ++iter )
96 {
97
98 // Save the old coordinates:
99 double x = vertex_coords[count + 0];
100 double y = vertex_coords[count + 1];
101 // double z = vertex_coords[count+2];
102
103 // Apply the rotation:
104 vertex_coords[count + 0] = x * std::cos( ANGLE ) - y * std::sin( ANGLE );
105 vertex_coords[count + 1] = x * std::sin( ANGLE ) + y * std::cos( ANGLE );
106
107 count += 3;
108 }
109
110 // Now, the vertex_coords vector contains all of the updated
111 // coordinates. Let's push these back into MOAB:
112 mbint.set_coords( vertex_range, vertex_coords.data() );MB_CHK_SET_ERR( rval, "set_coords" );
113
114 // **************************
115 // * Write Mesh to File *
116 // **************************
117
118 rval = mbint.write_file( "mbex2.vtk" );MB_CHK_SET_ERR( rval, "write_file(mbex2.vtk) failed" );
119
120 // Now you can open your favorite visualization tool (VisIt or ParaView)
121 // and look at the original (mbex1.vtk) and rotated (mbex2.vtk) meshes.
122
123 return 0;
124 }
References moab::Range::begin(), moab::Range::end(), ErrorCode, moab::Interface::get_connectivity(), moab::Interface::get_coords(), moab::Interface::get_entities_by_type(), moab::Interface::load_file(), MB_CHK_SET_ERR, MBHEX, MBVERTEX, PI, moab::Interface::set_coords(), moab::Range::size(), and moab::Interface::write_file().
1.9.1.