ofMesh point cloud with edges

I want to visualise the edges joining specific pairs of points in a point cloud that I’ve defined using an ofMesh. Is this possible? If so how do I do this (add edges to an ofMesh)?

Also if it can be done, will it also work if I exported it to a .ply file and viewed it with meshlab?

I’ve resorted to manually drawing the lines by sampling points on the line between the end points.