Load Marked mesh in cpp for parallel running

mesh
1

I am trying to load a mesh along with a mesh function and boundary function in cpp. The old approach of using

auto mesh = std::make_shared<Mesh>("./startfiles/mesh.xml");
auto mf = std::make_shared<MeshFunction<std::size_t>>(mesh,"./startfiles/mf.xml");
auto bf = std::make_shared<MeshFunction<std::size_t>>(mesh,"./startfiles/bf.xml");

no longer works in parallel, and I am trying to transition away from using xml mesh files and start using meshio. However, I have so far not had any luck importing .h5 or .xdmf mesh function files in cpp in parallel. Does anyone have a simple example of how to do this?

Apologies if I have missed an obvious solution that someone has already given, I have not managed find an answer in

or

so far, or in the standard fenics demo’s.

2

You should be able to translate the example used here Transitioning from mesh.xml to mesh.xdmf, from dolfin-convert to meshio directly to C++.

from dolfin import * 
mesh = Mesh()
with XDMFFile("mesh.xdmf") as infile:
    infile.read(mesh)
mvc = MeshValueCollection("size_t", mesh, 2) 
with XDMFFile("mf.xdmf") as infile:
    infile.read(mvc, "name_to_read")
mf = cpp.mesh.MeshFunctionSizet(mesh, mvc)

There are no functions used to load the mesh or mesh-function here that are python specific. They are just bindings to c++ functions.

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3

That’s the answer :slight_smile: For completeness, some c++ code is below,

auto mesh = std::make_shared<Mesh>();
XDMFFile initialmeshfile(MPI_COMM_WORLD, "./startfiles/mesh.xdmf");
initialmeshfile.read(*mesh);

MeshValueCollection<std::size_t> mf_mvc(mesh, 3);
XDMFFile initialmffile(MPI_COMM_WORLD, "./startfiles/mf.xdmf");
initialmffile.read(mf_mvc, "name_to_read");
auto mf = std::make_shared<MeshFunction<std::size_t>>(mesh, mf_mvc);
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