Splitting mesh into connected components in Openmesh

I have an obj file mesh and I want to extract connected components from it through OpenMesh. I can find boundary vertices and edges, but is there a way to directly split mesh into connected components in Openmesh ?

This functionality is not provided by OpenMesh (the goal of the library is only to provide a mesh data structure). The OpenFlipper, a mesh processing library built on top of OpenMesh, is a more suitable candidate but also does not provide this functionality. You can however find in the codebase in MeshTools/MeshInfoT.cc a componentCount function that counts the number of connected components (it simply does a depth-first search on the vertex graph).

Based on this function, you should be able to write code to split a mesh into its connected components:

1. Add a connected component number property per vertex (initialized to -1 for instance, which means the vertex has not been visited yet).
2. Traverse the mesh vertices with a depth-first search (or breadth-first search..), and set this component number for each vertex:
   1. When an unvisited vertex is found, increment the current connected component number and create a new connected component. The found vertex is used as a seed vertex for this component.
   2. Set the component number of all the vertices traversed from the seed vertex of the connected component.
3. Once the traversal is done, the total number of connected components is known and for each vertex, its component number is also known. From this information the connected component meshes can be built (all the vertices belonging to a component are known, and the faces can be identified using the half-edge reference of the vertex). For each connected component:
   1. Create a new mesh for this connected component.
   2. Add all the vertices from the same connected component. Create a mapping from vertex handle in the initial mesh to the corresponding vertex handle in the new mesh for the connected component.
   3. Find all the faces of the component: to achieve this, a simple way can be to iterate over all the vertices of the component and for each vertex iterate over all the faces it belongs to. For each newly traversed face, create a face in the new component mesh referencing the new vertex handles (using the mapping from old to new vertex handles).