#34 Document the meaning of (the unspecified) mass in inertia.h

[peci1]

I refer to vcg/complex/algorithms/inertia.h, which is for example used by Meshlab to compute the inertia tensor.

However, I don't really understand how the library can compute a mass-dependent value without utilizing a user specified mass of the body. So I thought VCG just uses a unit mass, or just uses the volume of the body instead of the mass.

But these are only my thoughts, and there is no place which would support any of the available interpretations. By just looking at the source, the Mass() method returns T0, but who knows what's that?

I suggest somehow clarifying this in the docs.

[peci1]

Well, I've found out the meaning myself. This function treats the volume of the mesh as its mass and the resulting inertia tensor is premultiplied with this "mass". If you e.g. watch the results in Meshlab, the volume is also written out when you specify to compute geometric properties. Along with the computed bounding box, you should be able to compute the correct inertia tensor for your mesh with the correct mass and scale. It seems the inertia tensor is computed relative to the center of mass, and not relative to the origin.