Join George Maestri for an in-depth discussion in this video Working with set-driven keys, part of Maya: Character Rigging.
Now let's talk about some advanced rigging controls, most specifically, set-driven keys. Now these can be used to really add a lot more control to your rig. Now you may have used set-driven keys before, but let's go ahead and do a quick refresher on how to use them, and then we'll go ahead and start using them for more character animation related tasks. So I've got a simple joint chain here and I've got an arrow that we can use as a control.
Now this arrow, we can move it up or down, and we can use that to, for example, control the rotation of these joints. And we're going to do it using what's called a Set Driven Key. Now you can find set-driven keys under the Animation menu under Animate. We have something here called Set Driven Key. In fact, let's go ahead and open up the menu, and when we hit Set it brings up this Set Driven Key menu, and then that allows you to use the attributes of one object to drive attributes in another.
If we take this joint, we can drive the rotation of this joint by the position of this arrow. So, for example, if I wanted to rotate this joint around say, the Z axis, I could load this as the Driven object. It's kind of like a constraint, whereas you have the constraining object and the constrained object. So in this case, we have the Driver and the Driven. So I'm going to load this joint as the Driven object, and then I'm going to click on this arrow and load that as the Driver.
So in this case, I want the joint's Z axis to be controlled, or to be driven, and then I want to be able to move the object along the Y axis. So I want Translate in Y to control Rotate in Z. So I can go ahead and hit a Key. And when I do, you'll see that this lights up and that says that it's actually keyframed. And if I click on this joint, you'll see that the Rotate Z actually has a keyframe.
So now I can move this object to a different position, then select the joint and rotate it to how ever far I want that to be rotated when this object is at that position. Then all I have to do is hit Key again, and now we've got two set-driven keys. So when I move this object, you'll see that when it's at zero, which was the original position, this also is at its original position.
And then as I move this up, it goes only to that point where I set the key, and then it stops moving. Now I don't need to use this just for two keys, I can also do multiple keys. So if I wanted to I can move this down below zero, select the joint again, and maybe rotate it the other way and hit Key. So now I have three set-driven keys. These are basically like animation keys. So when the arrow is here, the joint is here, goes through zero and then here, and then it stops.
So this can really give you precise control over how an object behaves, and you can also tie objects together in a one-to-one relationship. Now if I select my joint which has the set-driven key, and go into my Graph Editor, you'll see that I actually have an animation curve, and when this object here is at its maximum, then this curve here is also at its maximum.
So you can see how Rotate here is connected to Translate. And I can select these curves, and if I want to I can actually move them around, and actually change the way that that in between work. So I have a lot of control over this. Now I can also have one object control many objects. So if I wanted this to bend more than one joint I could just set a set-driven key on this second joint, and have both of them rotate as well.
So those are some of the basics of set-driven keys and we're going to be using them in the next few lessons to control the character's hand.
- Understanding the basics of rigging
- Creating skeletons
- Modifying joint attributes
- Working with inverse kinematics and constraints
- Rigging characters
- Using Maya's new HumanIK skeletons/rigs
- Setting up an FK/IK switch
- Creating custom facial rigs
- Binding skin using Smooth Bind
- Painting and editing skin weights
- Using expressions to rig a character's mouth controls
- Controlling eye direction
- Finalizing a rig