Exporter from Sins Mesh to what? Wavefront obj.? Or something else?
If your looking to make a script for 3D max 1 has already been made.
The direction of normal's is associated, I believe, with which way the polygons face's is facing, outwards or inwards from the model. If a model is imported / exported with inverted normals, it will affect how components can be selected in some programs(the ones that I am familiar with anyway).
Also I think, but am not real sure, that if the model has inverted normals, the normal map's effects will appear reversed.
As far as how these normals are calculated I am not sure, I would think that there directional Coordinates are universal between programs & there is no calculations needed, the values are already there and conversion to a relevant convention is all that's needed. But there is a difference as to what different programs call the XYZ. Z in 1 program can be Y in another. As I mentioned I am not real sure about this, but that's my understanding, I could be completely wrong.
