This small example shows how to remove faces and vertices from a mesh.
If we want our mesh class to be able to remove vertices, faces or edges we have to extend the default traits for our mesh class. Vertices, faces and (half-)edges need the OpenMesh::Attributes::Status attribute which is used to hold the flag "deleted" if an element is deleted.
After having created the geometry of the cube one can delete faces and vertices by simply calling delete_vertices() (delete_faces() or delete_edges() respectively).
Note that there is actually no way to directly delete halfedges since they are automatically affected when the parent edge is marked as deleted!
where handle is either a vertex-, edge- or face-handle.
In this example we delete all faces except one and the corresponding vertices. The code looks like this
mesh.delete_face(fhandle[0], false);
mesh.delete_face(fhandle[2], false);
mesh.delete_face(fhandle[3], false);
mesh.delete_face(fhandle[4], false);
mesh.delete_face(fhandle[5], false);
mesh.delete_vertex(vhandle[0], false);
mesh.delete_vertex(vhandle[1], false);
mesh.delete_vertex(vhandle[2], false);
mesh.delete_vertex(vhandle[3], false);
Now the deleted faces and vertices are marked as "deleted" internally. Call garbage_collection() to definitely remove them from memory.
#include <iostream>
#include <OpenMesh/Core/IO/MeshIO.hh>
#include <OpenMesh/Core/Mesh/PolyMesh_ArrayKernelT.hh>
#include <OpenMesh/Core/System/config.h>
#include <OpenMesh/Core/Mesh/Status.hh>
{
};
int main()
{
MyMesh mesh;
MyMesh::FaceHandle fhandle[6];
std::vector<MyMesh::VertexHandle> tmp_face_vhandles;
tmp_face_vhandles.clear();
tmp_face_vhandles.push_back(vhandle[0]);
tmp_face_vhandles.push_back(vhandle[1]);
tmp_face_vhandles.push_back(vhandle[2]);
tmp_face_vhandles.push_back(vhandle[3]);
fhandle[0] = mesh.add_face(tmp_face_vhandles);
tmp_face_vhandles.clear();
tmp_face_vhandles.push_back(vhandle[7]);
tmp_face_vhandles.push_back(vhandle[6]);
tmp_face_vhandles.push_back(vhandle[5]);
tmp_face_vhandles.push_back(vhandle[4]);
fhandle[1] = mesh.add_face(tmp_face_vhandles);
tmp_face_vhandles.clear();
tmp_face_vhandles.push_back(vhandle[1]);
tmp_face_vhandles.push_back(vhandle[0]);
tmp_face_vhandles.push_back(vhandle[4]);
tmp_face_vhandles.push_back(vhandle[5]);
fhandle[2] = mesh.add_face(tmp_face_vhandles);
tmp_face_vhandles.clear();
tmp_face_vhandles.push_back(vhandle[2]);
tmp_face_vhandles.push_back(vhandle[1]);
tmp_face_vhandles.push_back(vhandle[5]);
tmp_face_vhandles.push_back(vhandle[6]);
fhandle[3] = mesh.add_face(tmp_face_vhandles);
tmp_face_vhandles.clear();
tmp_face_vhandles.push_back(vhandle[3]);
tmp_face_vhandles.push_back(vhandle[2]);
tmp_face_vhandles.push_back(vhandle[6]);
tmp_face_vhandles.push_back(vhandle[7]);
fhandle[4] = mesh.add_face(tmp_face_vhandles);
tmp_face_vhandles.clear();
tmp_face_vhandles.push_back(vhandle[0]);
tmp_face_vhandles.push_back(vhandle[3]);
tmp_face_vhandles.push_back(vhandle[7]);
tmp_face_vhandles.push_back(vhandle[4]);
fhandle[5] = mesh.add_face(tmp_face_vhandles);
mesh.delete_face(fhandle[0], false);
mesh.delete_face(fhandle[2], false);
mesh.delete_face(fhandle[3], false);
mesh.delete_face(fhandle[4], false);
mesh.delete_face(fhandle[5], false);
mesh.delete_vertex(vhandle[0], false);
mesh.delete_vertex(vhandle[1], false);
mesh.delete_vertex(vhandle[2], false);
mesh.delete_vertex(vhandle[3], false);
mesh.garbage_collection();
try {
std::cerr << "Cannot write mesh to file 'output.off'" << std::endl;
return 1;
}
}
catch( std::exception& x )
{
std::cerr << x.what() << std::endl;
return 1;
}
return 0;
}