After having written the article on Quadruped Walkcycle it inspired me to do a little cat animation. The cat character is fully rigged with lots of nice features built-in like Stretchy joints, Anti-popping and swivel joints important on the back legs of the cat in a sitting position for example when the (human equivalent) knee joint sticks out each side. The clockwork mouse is as well rigged but this is a lot easier to do as it is mechanical it too has a few interesting features and solutions to various problems encountered in the animation process. So in this article, I will be breaking down the process of rigging the clockwork mouse.
So getting back to the mouse the wind-up key is animated using a Post Infinity cycle with Offset (this just means the key is keyframed in Rotate-Y on frame 0 and again on frame 20) make sure the Tangent is set to Spline (you don't want the cycle to slow down and speed up this would be an S-shaped curve you need a diagonal line like this /) and that's it, it will now rotate in Rotate-Y forever. This of course could have been hand animated over the length of the timeline but doing it this way it is done you can forget about it. The tail is probably the most complex element in this rig and for this animation, I created two variations for which you can create an SDK to switch between them using Visibility ON/ OFF. (1) dynamic joint chain with FKcontrols parented to clusters attached along the curves vertex points. This process I have covered in a lot more detail in another article Character Rigging so I won't repeat myself. You could just create a dynamic joint chain but the point of adding FK control curves on the joints is to give your rig a second layer of control. As I always say while rigging it is better to have as many options as possible as you never know what the animator will need to achieve a certain look or effect!. If you have problems doing all this yourself there is a really great Maya plug-in called Jiggle Box that will automate this entire process for you. (2) I created a Maya nCloth tail also and in the Nucleus node check the box use the ground plane (the ground plane becomes a collision object so your tail does not just fall down under the effects of gravity). Use the nCloth systems nConstraint Point to Surface and use Weld, select a few of the vertices at the start of the tail and Ctrl-Click a piece of geometry and apply the constraint now the tail is attached in this case to the mouse and will follow along with the rig. The ears this is just one piece of geometry and it is parent constrained to the mouse's body geometry then selecting vertices on each ear left & right add a Maya native Jiggle constraint this will result in a perfect little jiggle effect throughout the animation. Important note: this is only happening because the mouse's body group has a Shake effect applied to it!. The ears are therefore jiggling as a side effect of the body shaking. If you want to know more about the shake effect check out the article called Secondary Motion you will discover everything you need to know about setting up this effect to use with your rigs. The eyes are just modelled to look like those old fashioned teddy bear eyes, glass with a black pupil in them nothing complicated here the same goes for the wheels. The front wheel of course has a control curve to animate Rotate-Y (left & right) direction that is hand-animated.