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I am building index and vertex buffers from OpenMesh structures which I will feed into my rendering engine. Here I iterate my elements (not shown) and create VertexHandles for each of my points and then add the face.

std::vector<Mesh::VertexHandle> vhandles;

for (... 3 triangle points) {
    vhandles.push_back(mesh.add_vertex(Mesh::Point(
        point->px, point->py, point->pz)));
}

mesh.add_face(face_vhandles);

The vertex buffer for a Point appears below and I copy the vhandles data into this struct, then build an array of these to feed to the graphics engine.

struct Point
{
        float px, py, pz;   // positions
        float nx, ny, nz;   // normals
        float cx, cy, cz;   // diffuse
}

When I build the vhandles vector above, I did not add an index/id to the VertexHandle.

I need to somewheres store and have access to the id of the point with the VertexHandle iteself. Where would I store that? I've not yet found a field for this purpose within the source of a VertexHandle, but seems like something that would be needed.

Ender
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  • Clarifying - you want to save a mapping between the original mesh (OpenMesh) and your constructed array of `Point`? – Mark Loyman Oct 26 '20 at 20:44
  • No. I just wanted a field to store the id within the original OpenMesh::Point or OpenMesh::VertexHandle. Botond has an interesting comment that I'm going to comment on. – Ender Oct 26 '20 at 21:06

1 Answers1

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Although I'm still just getting familiar with OpenMesh, it seems to me like a bad practice to access any element by their index because these are internal indices that will be rearranged upon garbage collection. OpenMesh provides iterators and circulators to iterate over its elements. If you need random access, you can always store the handles associated to whatever index you want in a container. Also, there are the vertex_handle(), face_handle(), edge_handle() functions which give you mesh elements by their internal indices.

Botond
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  • As it turns out, the indices will work just fine for me and although you say they are rearranged upon garbage collection ... at that point (when destroying) I won't care anymore. But your answer helps. – Ender Oct 26 '20 at 21:09