1+ # Support for Gmsh meshes
2+
3+ module Gmsh_utils
4+
5+ using GridapGmsh
6+
7+ import GeophysicalModelGenerator: import_Gmsh, FEData
8+
9+ """
10+ fe_data, tag_names = import_Gmsh(fname::String)
11+
12+ Reads a Gmsh file and returns a `FEData` object with info about the mesh. `tag_names` contains the names of the regions of the FE mesh
13+ """
14+ function import_Gmsh (fname:: String )
15+
16+ mesh = GmshDiscreteModel (fname, renumber= false )
17+
18+ # Extract vertices
19+ nverts = length (mesh. grid. node_coordinates);
20+ dims = length (mesh. grid. node_coordinates[1 ])
21+ vertices= [mesh. grid. node_coordinates[n][i] for i= 1 : dims,n= 1 : nverts]
22+
23+ # write coords as 1D double array
24+ nvertices_cell = length (mesh. grid. cell_node_ids[1 ])
25+ connectivity = [c[i] for i= 1 : nvertices_cell, c in mesh. grid. cell_node_ids]
26+
27+
28+ regions, tag_names = cell_tags_from_gmsh (mesh) # extract number of each of the tetrahedrons
29+
30+ cellfields = (regions= regions,)
31+ fields= nothing
32+
33+ return FEData (vertices,connectivity, fields, cellfields), tag_names
34+ end
35+
36+
37+ """
38+ tags, tag_names = cell_tags_from_gmsh(mesh::GmshDiscreteModel)
39+
40+ Returns a list with integers that are the tags for each of the cells
41+ """
42+ function cell_tags_from_gmsh (mesh)
43+ cell_entities = mesh. face_labeling. d_to_dface_to_entity[4 ] # volumetric entities
44+ cell_entities_unique = unique (cell_entities)
45+ tag_unique = zeros (Int64,size (cell_entities_unique))
46+
47+ for i= 1 : length (cell_entities_unique)
48+ for (n,tag) in enumerate (mesh. face_labeling. tag_to_entities)
49+ if any (tag .== cell_entities_unique[i])
50+ tag_unique[i] = n
51+ end
52+ end
53+ end
54+
55+ # create tags for cells
56+ tags = zeros (Int64,length (cell_entities))
57+ for (i,entity) in enumerate (cell_entities_unique)
58+ id = findall (cell_entities.== entity)
59+ tags[id] .= tag_unique[i]
60+ end
61+
62+ return tags, mesh. face_labeling. tag_to_name
63+ end
64+
65+
66+ end
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