pub fn inertia_tensor_box(mass: f32, half_extents: Vec3) -> Mat4
Compute inertia tensor for a solid box (principal moments) Ixx = (1/12)m(h^2 + d^2), Iyy = (1/12)m(w^2 + d^2), Izz = (1/12)m(w^2 + h^2)