Rigging The Character - Part 5 - Knee swivel
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You're almost done with the left leg.
So far you can move and rotate the foot controller
for a variety of primary motions,
and you have added and defined custom attributes to control various secondary rotations.
However, in some situations, mostly visible when you use the heel or toe twists, or even when you rotate the foot control shape,
the knee is not responding to that motion.
It would be nice to have the knee respond to the various rotations an animator is likely to introduce.
Select the Heel IK Goal and go to the Motion Panel.
At this time, it is in the "Start Joint" parent space.
This means that the swivel angle is set in the same orientation as the thigh bone, the first bone in that chain.
Select the IK Goal option instead, to have the swivel angle follow the heel IK goal.
Now when you rotate the foot control,
or edit the twist custom attributes, the knee behaves accordingly.
Still, you will need additional control over the swivel angle.
There may be cases where the animator needs a little bit more or a little bit less of a swivel.
One choice is always to select the IK Goal and edit the Swivel angle value in the Motion Panel.
However, this method is impractical, especially after going to such great length to create custom attributes to simplify the animator's job.
And so, you will simply add another custom attribute to control the swivel angle from the same interface as before, meaning the Foot Controller.
If you've made Transform changes to the foot control shape, transform it back to Zero.
Go to the Modify panel to display the Attribute Holder modifier.
Using the Parameter Editor dialog, add another custom attribute to the mix.
Name it "Knee Swivel" and set it the same way you set the others.
Make sure its range goes from -10 to +10 as you need swivel control in both directions.
When you've added it to the modifier, you can exit the dialog.
In the Reaction Manager, add a new Master Reaction based on the newly created Knee Swivel custom attribute.
Now select the heel IK Goal and use the Add Selected icon to wire its Swivel angle to the custom attribute.
Add two new states and set the maximum and minimum values to range from 90 to -90 degrees.
You may need to reverse the angles based on your personal preference.
If you prefer the knee to swivel outward when the custom attribute is positive, then you need to reverse the maximum and minimum angles.
Close the dialog when done.
With this you get the best of two worlds because even through the knee swivels when you rotate the foot or twist the toe or heel,
you can still fine-tune the solution by toning down or boosting up the swivel value.
This gives the animator more flexibility in all situations, which is ultimately your goal: making the animator happy.
Your left leg is now rigged but as mentioned previously, there is no magic button to duplicate your work to the right leg.
So before moving on to rigging the spine, it is time for you to run a bit on your own, and rig the right leg much like you did the left leg.
You can still use the left leg rigging movies as a reference, but try to do this on your own.
You may find that the process isn't that hard after all, not after you've been through it once.
When you're done, the legs would be completely rigged and the character's lower body ready to pose.
With the work you have done, it now becomes very easy to pose the lower body in any way you want.
In the next movie, you rig the spine.
