A mesh that never curves or bulges inwards. A sphere and a box are simple examples of convex meshes. Dynamic and kinematic rigid bodies must use a convex hull or hulls for the physical mesh, while static rigid bodies may can a concave mesh for the simulation. For more information, see the section “Adding an object to the simulation”.
The physical mesh is moved by the simulation, and the graphical mesh in Max is updated from that. You cannot use a concave physical mesh for a dynamic object, but the Composite Mesh option lets you use multiple physical meshes in the form of a concave mesh.
Kinematic objects (rigid bodies and skeletons) are puppets moved by the strings of your animation. They do not fall with gravity. They push any dynamic objects they encounter but cannot be pushed by other objects.
The graphical mesh for a kinematic object is controlled by 3ds Max (animated or not), which in turn controls the transform of the physical mesh representing the object in the simulation. You cannot use a concave physical mesh for a kinematic object, but the Composite Mesh option lets you use multiple physical meshes in the form of a concave mesh.
You can convert a kinematic object to dynamic at any point during an animation with the Until Frame settings, available on the Rigid Body Properties rollout and on the Edit panel of the MassFX Tools dialog.
Static rigid bodies are similar to kinematic, except that they cannot be animated. Dynamic rigid bodies can bump into a static rigid body and bounce off of it, but the static rigid body never moves. Static objects are useful both for performance optimization and also because you can use concave meshes for them.