yade-users team mailing list archive

[Václav Šmilauer <eudoxos@xxxxxxxx>]

> Currently the inertia matrix is a .... vector!
> 
> This vector is just a diagonal of that matrix. Did the time come to fix that?

No reason for that. If your local axes are aligned with principal
inertia axes, the matrix is diagonal. And that is (as I take it)
definition of the "right" orientation of body-local coordinate system.

Clumps also recompute orientation, to be oriented in the principal
directions.

The problem would be that you have to create the matrix3, assign the
principal values to the diagonal (from the principal inertia vector) and
transform that matrix. But that is computatinally quite expensive and
most bodies (spheres) don't need it since the transofmration is
identity.

See Clup::inertiaTensorRotate and also
http://www.kwon3d.com/theory/moi/triten.html

v.