June 8, 2006
A lot of people ask me what goes into a rig? – This really isnt a question you should be asking but rather what does the character need to do?. There are however a certain set of key features most rigs have and need, bar all the stretch and even twist setups:
- A method to control the entire torso.
- A method to control the upper torso.
- A method to rotate/move the hips independent of the torso.
- A method to rotate/move the chest independent of the hips and head.
- Shoulder controls
- FK/IK arms and legs
- FK foot controls
- A method to rotate the foot at the heel, ball and toe.*
- Animatable pivots
- Curl controls on fingers, pose tool etc.
*I generally have an expression that drives the entire foot roll – its an important feature to have, as for quick lifts etc it’s neccesary. Eg walking up a ladder. I also introduce ‘Natural Foot’ which allows the foot to ‘peel’ off its controls, if it reaches to far.
From developing 40 or so rigs for my last company, we came up with a pretty solid rig splitting the torso into two parts: ‘Torso’ and ‘Upper Torso’ – Torso essential drives everything from the pelvis up. With Upper Torso driving the head, neck arms and chest.
The need to lock the head either by a target or just its orientation is crucial too – personally I still like to be able to move/rotate the head with the torso and upper torso controls, including a blend to lock the head when needed.
With skinning you need to introduce twist bones, these essentially can be as many bones as you want. Valve with HL2 introduced ‘interpolator’ bones at elbows, shoulders, knees etc, to aid skinning.