def extend_function_to_3d(func, mesh_extruded):
"""
Returns a 3D view of a 2D :class:`Function` on the extruded domain.
The 3D function resides in V x R function space, where V is the function
space of the source function. The 3D function shares the data of the 2D
function.
"""
fs = func.function_space()
# assert fs.mesh().geometric_dimension() == 2, 'Function must be in 2D space'
ufl_elem = fs.ufl_element()
family = ufl_elem.family()
degree = ufl_elem.degree()
name = func.name()
if isinstance(ufl_elem, ufl.VectorElement):
# vector function space
fs_extended = get_functionspace(mesh_extruded,
family,
degree,
'R',
0,
dim=2,
vector=True)
else:
fs_extended = get_functionspace(mesh_extruded, family, degree, 'R', 0)
func_extended = Function(fs_extended, name=name, val=func.dat._data)
func_extended.source = func
return func_extended
