replacing shape nodes

you may ask what’s the advantage of replacing shape nodes in maya since it doesn’t make sense in the first place. but doing so can be enormously helpful when you need to access specific joints or clusters in a rig so they can serve as controls to be accessed easily. the following example explains it:

Create 3 joints in one row in an orthographic view. now create a nurb circle and point snap (v) it to the middle joint. rotate the circle by 90 degrees so that the bones are going through it. with the curve being selected, do a freeze transform and parent it to the middle joint (not vice versa, else you’ll break the parent connection from one joint to another!).
freeze transform again and now comes the tricky part: be sure your circle is still selected and launch the hypergraph; assure that shape nodes are displayed (options > display > shape nodes). press f (to focus to your selection), select the shape node of circle and shift select the joint.

now throw a mel command in the mel command line:
parent -r -s;
to clean up, you may delete the transform node of the circle – you don’t need this anymore.

you’re done; what happened? the circle is now the shape node of the joint and selecting it (e.g. from outside a character’s skin) equals the selection of the joint itself.

 

the same procedure can be followed with clusters or any other geometry. this is especially useful fur a spine rig where you don’t want to access the small clusters c’s in the character themselves but an easily accessible control. this trick should definitely help making your rig more animator friendly.
last but not least: michael comet has a nice little mel script collection, one of them (wireShape) creates simple shapes like arrows, bulbs etc. to be used as controllers. go grab it and install it in your scripts folder, there are several other very useful little helpers in his collection.

http://www.onoff.ch/2008/03/22/replacing-shape-nodes/