System Information
Windows 7 64, HD 5770
Blender Version
Broken: 9337574 (2.71 release) + 35bc266
Short description of error
Objects with Skin modifier dont show up in Game Engine if its geometry have 0 (zero) faces.
Exact steps for others to reproduce the error
I'm pretty sure the BGE was never able to render objects without faces unless you assigned a wireframe shader to it.
The mesh doesn't have a surface to begin with, and most surface shaders are designed to work with faces, so no surface means nothing solid to render. You'd get the same using BI and Cycles.
Not sure what you mean, Skin works just fine in BI and Cycles.
The problem is indeed that GE searches a face to display the skinned mesh.
A workaround for example is to add one face, and then hide it with mask modifier, before other operations follow.
Campbell says Skin generally works best with loose edges - you can test this by yourself very easily with a monkey mesh + Skin modifier.
So I still hope this is an issue that can be solved by code.
@Mitchell Stokes (moguri), @Inês Almeida (brita_), can you look into this report please?
I really don't understand this bug report : Why apply a skin modifier on an empty object ?
With 0 face object I mean a mesh without faces, not an empty.
You can use it for low poly meshes or stylized geometry (bone meshes, water waves)
or for (roots of) a tree, for example. Simply what you want.