Creating animation for rigid body assets
Sometimes it is not required to skin the geometry to bones for deformation, but rather animating the nodes' movement and rotation directly within 3ds Max might be preferred. Animated hard body geometry data only supports directly linked objects and does not support skeletal-based animation. Some good examples of Rigid Body animation could be a rotating radar dish, the precomputed destruction of a building, or other such assets.
It is composed of two file types:
.cga
(Crytek Geometry Animation).anm
(Additonal Animation)