openmesh EdgeHandle class

Question

So I'm using the OpenMesh library for a project and I'm passed in an EdgeHandle e to a method. Is it possible to see what two faces are joined by this edge? I tried looking online but the documentation for openMesh is very sparse and the stuff for EdgeHandle is even sparser.

score 3 · Answer 1 · edited Aug 11 '15 at 20:24

3

Yeah, the OpenMesh "documentation" is pretty aggravating. However, from searching for the face_handle mentioned by tintin, I found this page hidden in it which gives a large number of useful functions: http://openmesh.org/Documentation/OpenMesh-2.4-Documentation/classOpenMesh_1_1Concepts_1_1KernelT.html

Using the stuff found there, the following works for me:

FaceHandle a = mesh.face_handle(mesh.halfedge_handle(e,0));
FaceHandle b = mesh.face_handle(mesh.halfedge_handle(e,1));

(Technically, I enclosed the right hand sides in a function call, so I haven't tried this exactly as written. The right-hand sides should return some form of FaceHandle, at least.)

edited Aug 11 '15 at 20:24

Ren

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answered Mar 04 '14 at 23:18

Erhannis

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Just a side note, this assumes that the original mesh object is also passed as a parameter, or is a global variable. – Ren Aug 11 '15 at 20:26
2

Your code assumes that your edge `e` has two incident faces. If it doesn't (i.e. if it is a boundary edge), `mesh.halfedge_handle()` returns an invalid handle causing undefined behavior when passed to `mesh.face_handle()`. So you might want to check `mesh.halfedge_handle(e, i).is_valid()`. – hc_ May 02 '16 at 14:00

score 0 · Answer 2 · answered Jan 06 '14 at 07:38

It's not hard to deal with this,

HalfedgeHandle halfedge_handle(VertexHandle _vh) const {
    return vertex(_vh).halfedge_handle_;
}

using this function, you will be able to generate a half edge handle with the edge_handle. and you can

mymesh.face_handle(_hh);
mesh.face_handle(mesh.opposite_halfedge_handle(_hh));

to get the two face_handle you need.

openmesh EdgeHandle class

2 Answers2