Gasping for air

So my LDR mesh importer is far from complete, but its a good start. If I want to build meshes at runtime suitable for GPU skinning there is still more work to do. I've broken the back of the mesh pipeline but do have a couple of bugs to ponder over before pushing too far ahead.

The LDR format isn't really designed with run-time performance and games in mind. They models are generally high detail - in many cases higher detail than I need but not without flaws in the geometry. Model 3838, the classic space Air Tank, is a good example of a well detailed model that diverges from games requirements - Its hollow. Being hollow is great for injection molding but not so great for realtime 3D. I could cap the ends and save the internal geometry. Actually, a lot of LDR models are brick-accurate in ways like this that are irrelevant to me.
Secondly, the AirTank is clearly several submeshes, and I'd rather have one mesh per element.

The LDR format doesn't specify a winding order - worse it specifies that winding order is irrelevant. However, I'm using counter-clockwise triangles so have had to write a Unify Normals mesh post-processor which isn't too much work.

Couple this with the knowledge that the meshes are not contiguous, which means you can't walk the geometry and unify normals. This is something of a shame, and demonstrated here.
The AirTank element is recognizably made from three or four non-contiguous sub-meshes.
The crossbar at the top, the mounting harness and the two cylinder tanks.

The closeup demonstrates that the mounting harness contains a mixture of CW and CCW triangles by visualizing the vertex normals as red lines.

The lovely attention to detail is otherwise well appreciated.  Its just that in this instance it gets in the way of progress.

My solution is to reduce the model into its submesh components and unify the surface normals per submesh and then concatenate into the original mesh before saving out as a serialized bytestream.
My quick-fix, since silicon is free and infinite, is to disable back face culling and ignore the winding order. The increase in rendering is insignificant in the small scenes that I'm using.

By not occluding back faces, I can move straight on to building a skeleton, rig and skin out of my minifig mesh parts.