public void GetMassData(MassData data)
{
// data.mass = m_mass;
// data.I = m_I + m_mass * Vec2.dot(m_sweep.localCenter, m_sweep.localCenter);
// data.center.set(m_sweep.localCenter);
data.Mass = Mass;
data.I = I + Mass * (Sweep.LocalCenter.X * Sweep.LocalCenter.X + Sweep.LocalCenter.Y * Sweep.LocalCenter.Y);
data.Center.X = Sweep.LocalCenter.X;
data.Center.Y = Sweep.LocalCenter.Y;
}