In this tutorial we will be creating an IK setup, controls, and skinning for the little kitty above.

The first step is to make a model. This one is in NURBS, but you can make it in subdivison surfaces instead if you want.

MODELING



Make some curve circles and move them around til they look like the above illustration (I never said this was a modeling tutorial).




Loft it together so it looks like this. It is sort of rough with the seams, but since I put fur on it later it didn't matter too much.

SKINNING





Make a skeleton and stick some IK chains on it. (I used a spline IK for the back, Rotate Plane solvers for the legs, and lots of little IK's for each joint of the tail).




Now we're gonna skin it. But since I don't feel like editing a zillion control points on all of my NURBS objects, we are going to make a simple reference object (see above illustration) and skin that to the skeleton. There are way less points to edit so the skinning is manageable.

Then just attach the NURBS geometry to the polygon reference object with a wrap deformer, and you're done.

What's cool about this skinning method is that I also have a dummy object that I can animate with that is way less heavy than my detailed model (see below), so it goes faster.

And I can even unwrap my model, make changes to it, and then re-wrap it without having to do the weighting all over again since it is done on the simple reference object.

CHARACTER CONTROLS

So now comes the part you've all been waiting for: The Character Setup! Hooboy! We're gonna get a bit complicated now, so hold on to your hat.

We want to have three basic kinds of controls here:

* Translation and Orientation controls
* Toe Roll Controls
* Spline Handle Controls



Translation/Orientation Controls


As you can see above the controls are curves. These don't render and are easier to pick then the IK itself and you have more control over them as we will see below.

Let's start with Translation and Orientation Controls: this is for stuff like hands and arms where I want a control on the wrist that I can use to move the whole arm around with IK and also rotate to move the hand. On the cat I have a control like this on his head so he can rotate his head and also crouch down with his shoulders. In the picture above this curve is picked (green).



Translation/Orientation Controlls

Translation Control
1) In the modeling view, snap the curve's position onto the joint (like the wrist)

2) In the hypergraph, parent the curve to the skeleton, (see above illustration). What is important is that the curve is one level higher than the influence of the IK's effect (the little red dotted line).

3) Freeze transformations on the curve. This is so you don't have crazy values when you begin animating.

4) Parent the IK handle to the Curve. Now you have the transformation controls, next we do the rotations:

Orientation Control
5) Parent a locator to the curve, and snap its position to the same joint as the curve too.

6) Orient constrain the locator to the rotating joint (the hand for instance).

The Locator is so you don't have to worry about local axis rotation, if it flips anyway when you constrain it, you may have to adjust the local axis rotation of the joint so it is the same as the locator.
.
Toe Roll Controls



Toe Roll is done in a similar fashion. This setup is a variant of the method used in Learning Maya 3 Handbook, except that I have used locators instead of joints. I like that better cause I found the joints ugly.

Since the IK is independant from the charater's heirarchy, you can make the basic setup once, and just import it into any scene and with a few adjustments and connections, you'll be done.

Download the Toe Roll setup to continue with the tutorial, or just look at the picture above, and the manual and figure it out yourself. But you'll need to add a bunch of driven keys for the toe roll.

After you have imported your set up in
1) scale it to your model using the GlobalScale, and then snap the footControll to your skeletons IK joint.

2) snap the position of the locators to your skeleton, like in the following illustration (the order matters because of the hierarchy).

After you have snapped the footControll in step 1, the heelL locator should already be in place automatically. Also in this illustration the Point_IK locator is at the same position as the heelL, but if your skeleton is different the Point_IK Locator should be on the same joint as your IK handle is, (but you already knew that right?).



3) Orient constrain the ball and ankle joints of your skeleton to Orient_ankle and Orient_ballJ.
4) Point constrain your IK handle to Point_IK
5) Template the heelL locator (the top locator on the hierarchy) since you will be animating the curves not the locators
Spline Handle Controlls


What we want to do here is make a spline IK, attach clusters to it and then attach curve handles to the clusters to animate them. The tricky part is getting the clusters attached to the skeleton hierarchy without having them freak out (step 5).

1) make clusters for each of the cv's you want to animate in your spline IK

2) make the Control curves you want to use to pick them and place them where you want. Rename them something memorable (in this example I named it "ShoulderControll" which is spelled wrong, sue me.)

3) parent the Control Curves under your Spline IK curve in your skeleton's hierarchy.

4) Freeze transformations on the Control Curves for keyframing later.

5) select "display -> shape nodes" in the hypergraph, and open the attribute Editor for the cluster shape node. Under the "weightedNode" category, type in the name of your Control Curve. This will automatically parent the shape node under the curve in the hierarchy.

6) parent the clusterHandle under the curve too. It should all look like the above illustration.

When you have multiple clusters (and you will) they should look like the illustration below:



Finishing up
One last thing: The hips. This is pretty easy but I thought I'd mention it anyway.

They should be set up like in the following illustration (basically you make a Control Curve, and stick the skeleton hierarchy underneath that):



if you want to have your hips be able to rotate independently of the shoulders (to get that boogie dancing effect) you can just add this expression:

Notice that I attach it to a locator under the Shoulder Curve, so I don't mess up my shoulder's Control Curves values for keyframing (like we learned in the first section).

shoulderLocator.rotateX = hipsCurve.rotateX * -1;
shoulderLocator.rotateY = hipsCurve.rotateY * -1;
shoulderLocator.rotateZ = hipsCurve.rotateZ * -1;

Well that's it. Have fun.

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