def get_triangle_mesh(file_name=None):
gmsh.model.mesh.generate(2)
if file_name is not None:
gmsh.write(file_name + ".msh")
# Renumber triangle node_tags array with indices into aVertex
node_tags, coord, parametric_coord = gmsh.model.mesh.getNodes(2, -1, True)
vertices = np.asarray(coord, dtype=np.float32).reshape(len(node_tags), 3)
node_tag_to_idx = dict()
for i, t in enumerate(node_tags):
node_tag_to_idx[t] = i
element_types, element_tags, node_tags = gmsh.model.mesh.getElements(2, -1)
assert len(element_types) == 1 and element_types[0] == 2
assert len(element_tags) == 1
assert len(node_tags) == 1 and len(node_tags[0]) == len(element_tags[0]) * 3
node_tags = node_tags[0]
temp_node_tags = np.empty(len(node_tags), dtype=np.int32)
for i, t in enumerate(node_tags):
temp_node_tags[i] = node_tag_to_idx[t]
triangles = temp_node_tags.reshape(len(element_tags[0]), 3)
mesh = Mesh(0, 0)
mesh.vertices = vertices
mesh.triangles = triangles
return mesh
