Mesh Lines - Horizontal and Vertical Edges

[_Aka_]

Same as here:

Using Unity's API, you can get the list of vertices and triangles of that mesh. From that, you can produce the list of lines making your mesh. Via dot product (or other means), you can deduce what lines are horizontal or vertical.

To get vertices : CGVMesh.Vertex.To get triangles CGVMesh.SubMeshes.Triangles
Examples of "other means": check the value of Vector3.Angle(Vector3.up, yourVector)