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Advanced IK Setups Added on: Thu Aug 03 2000 |
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Also the boot rotates about the tip of the toe like in real life. If you'd like to have the foot rotate about the ball of the foot, just simply create a foot position controller dummy under the ball of the foot. You can also use "effect pivot only" and move the pivot to any desired place.
Now that we have a working boot, and you understand the controls lets take a look at a Type 1 setup.
Type 1 Setup
The type 1 setup is a good place to start when learning an IK setup. Because once you start to use it for animation, it becomes very apparent to you the user, that it doesnt do what you need it to do. Actually what becomes apparent, especially to Maya and Softimage users, that in 3D-Studio Max, there is no Up-vector constraint (Softimage term) or a Pole Vector constraint (Maya term).
Now what is a constraint?
It is just that, a constraint. It constrains an object to another object. That object can be a null (dummy), an end effector, or even a light. But the point is that it constrains an objects movement to another object. A simple link is kind of a constraint in its simplest form.
However it really isnt a constraint because if i link a sphere to a box, i can then animate that sphere independent of the box, but i can still translate that sphere and its animation by moving the box.
A constraint doesn't allow the constrained object to be animated. Instead it knows to follow the object that it is constrainted to in what ever manner that the constraint is. There are different kinds of constraints such as, point,aim,tangent, etc Lets talk about the most relavent one to this tutorial, and that is the Upvector/Pole Constraint that i just mentioned.
Type 1 setup is bad?, Why even mention it!?
Ok so i've mentioned that a Type 1 setup has a problem, so why did i even mention the type 1 setup? Well the answer is simple. Normally in maya, you can do the type 1 setup with constraints becuase it has something called a Pole Constraint. In softimage this pole constraint is called an up-vector constraint. What is it?
Basically every chain you create has an up-vector. In otherwords it has a predetermined plane that defines an orientaion of the root.
For animation purposes, we use a constraint to constrain that up-vector/pole vector to a null. For max users, you can kind of imagine this as a look at controller that only controls the rotation of a single plane. Max lacks an up-vector constraint, so we have to make do with what we have. We can kind of get around this by using a trick. Granted its not as nice as having an up-vector constraint, and this trick does not simulate a real up vector constraint but it does allow you to controll the plane of your leg chain.
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