In this tutorial, Animation Mentor mentor Sidney Kombo-Kintombo, a Senior Animation Supervisor at Wētā FX whose credits include Avengers: Endgame, Avengers: Infinity War, and War for the Planet of the Apes, shares the constraint setup he uses in his own workflow. You will learn how to build a simple locator rig that lets you keep a hand constrained to a moving object while still having full freedom to animate it, without fighting the blend parent attribute.
Why Constraints Get Limiting
Constraints are great for locking a hand to a prop, but they are also restrictive. That lack of freedom can make animation feel stiff when you want something more organic and natural.
Sidney points to a character swinging a sword. With a basic constraint, the hand can only rotate so far before it hits a limit. Playing with the blend can work, but he finds it buggy and not very friendly. His setup is one approach among many.
The Basic Parent Constraint
The example scene is a character pushing a pillar twice, with the hand moving around as he pushes. To start, Sidney mutes the pillar animation so it stays static while he builds the constraints.
For the first hand, he selects the pillar, then the hand control, and creates a parent constraint with Maintain Offset turned on. Now when the pillar moves, the hand goes with it. The other hand gets a different setup.
Building the Locator Setup
For the second hand, Sidney creates a locator and names it right away. He stresses this habit: always name your locators and groups. On a production, a lead or supervisor may need to open your scene, and a clear setup makes life easier for the whole team.
- Name the first locator for the left hand with a “parent” label.
- Duplicate it and name the copy “child”.
- Make the child a child of the parent locator.
Next, line the parent locator up with the wrist control. Sidney constrains the parent locator to the hand control with Maintain Offset, just to snap it into place, then deletes that constraint. The goal is not to constrain the locator to the hand. It is only a quick way to get a perfect alignment.
Wiring the Constraints
Now the hand gets constrained to the child locator, this time without Maintain Offset. The child and the hand are both driven by the parent locator.
Finally, Sidney selects the pillar, then the parent locator, and creates a parent constraint with Maintain Offset. When the pillar animation is unmuted, the hand follows it as the character pushes. That is the basic setup.
The Blend Parent Problem
With the standard setup on the other hand, adjusting the pose means freeing the hand from the constraint. Keying the control creates a blend parent attribute that you have to key from zero to one at exactly the right moments. You also need keys on the hand controller itself, and then you have to set the blend back to one afterward.
It works, but Sidney finds it annoying. There are lots of places to go and a lot of timing to get right.
Animating the Child Locator
With the locator setup, the parent stays constrained the whole time and needs no keys. Instead, Sidney animates the child locator. He shifts the hand to the side as the character gets ready, pushes, then adjusts the hand position and orientation again before the next push.
Some unwanted motion can show up between keys, so he plateaus them to clean it up. He can also shift keys around freely to make the action more interesting, without worrying about blending constraints.
When to Use This Setup
The setup is simple, but it gives you full control over the animation without worrying about constraint limitations. It also helps when a character holds something with both hands and you need to adjust the pivot point.
Instead of freeing the constraint, adjusting the pivot, and locking it again, you just animate one locator for the hand. In short, you animate the locator instead of the controller.
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