This sets the finite rotation axis for a body. This axis only has meaning when the finite rotation mode is set (see dBodySetFiniteRotationMode). If this axis is zero (0,0,0), full finite rotations are performed on the body. If this axis is nonzero, the body is rotated by performing a partial finite rotation along the axis direction followed by an infinitesimal rotation along an orthogonal direction. This can be useful to alleviate certain sources of error caused by quickly spinning bodies. For example, if a car wheel is rotating at high speed you can call this function with the wheel's hinge axis as the argument to try and improve its behavior.