Capsules are the Muscle primitive objects that you can connect to the Maya Muscle skin deformer. They are basic Maya transform groups with a special shape node underneath that is used to convert polygon or NURBS objects to Muscle Objects that connect with skin.
Capsules are like Maya joints except that they have a shape and volume, which allows them to be used for Sliding effects. When Sticky weighted to skin, capsules deform the skin as they are moved, rotated, or scaled. This is similar to Maya skinClusters. Sliding weights cause capsules to push out the skin geometry based on their shape. Capsules can be non-uniformly scaled to get dynamic shapes.
You can create capsules from scratch or convert existing joints to capsules.
Before a polygon mesh can be used as a bone that deforms skin, it must have a Muscle Object shape node added. The only advantage to using a polygon mesh (instead of a capsule) as a bone object is that for Sliding effects the deformer uses the real shape of the polygon mesh. Sticky weights for polygon meshes are the same for capsules and bones, and are not based on surface deformation.
