Joint

The Joint object represents joint compression, which is a technique used to model two parts of a character pushing into each other, usually the arms or the legs. A bounding volume sphere is used on the LowerBone to do the pushing, and two nulls are used on the UpperBone to be pushed. For example, when the forearm comes into the bicep, the bicep deforms slightly as it is pushed by the forearm. The bounding volume is attached to the forearm and the nulls to the bicep to get a more realistic skin deformation.