3ds Max Animation with Biped

Bulges

Bulges can be used to make parts of the mesh bulge out when a certain angle is achieved between two consecutive links. For example, when a character flexes its arm, a bulge can appear in the bicep.

Bulges don’t work with ordinary keys; they work with angles. When the angle between one joint and the next is achieved, the bulge appears.

You set up bulges as an option under either the Physique or Skin modifier. In the Physique modifier, the Bulge sub-object is used to set the angle for the bulge, and the amount by which the mesh bulges when the angle is achieved. In the Skin modifier, you can select vertices and add a Bulge Angle Deformer gizmo to accomplish the same thing. You can find detailed information about these in the 3ds Max User ...