Tutorial: Animate a rotating pivot in 3ds Max

Learn how to animate a rotating pivot point using Autodesk’s 3ds Max software

Usually this type of problem is handled best by a simple rig of a few null objects. Even though a simple hierarchical rig or scripted controller are options, the first logical thing users want is to animate a pivot point.

It hasn’t always been possible in 3ds Max to animate the pivot point of an object so it can rotate around a different pivot at varying points in time, but in the more recent releases (2010 Subscription Pack and above), a new controller provides the ability to have an animated pivot point.

This functionality came along with the addition of CAT (Character Animation Toolkit) to the base package of 3ds Max. CAT has the functionality to animate pivots for rigs: it achieves this by adding a new Transform controller.

Fortunately, this controller can be added to any object to give it the ability to have an animated pivot point. Let’s have a look at this using a basic rolling cube example.

First, create a cube in the Top viewport. Go to the Motion panel and open the Assign Controller rollout.

Here, you will assign a new controller to the Transform track of the object.

It’s common to assign a controller to a Position, Rotation or Scale track, but it’s not too often that you would assign a controller to replace the entire Transform.

Select the main Transform track and click the Assign Controller button. From the list that appears, you may see a few new CAT controllers you haven’t seen before.

Choose CATHDPivotTrans. Now you have an extra track to play with that will allow you to animate your pivot point.

In the Motion panel, click the SubObject button to get into PivotControls SubObject mode. Move the pivot point to the left corner of the cube.

Turn on Autokey. At frame 10, rotate the cube over this side. Next, go back into SubObject PivotControls mode; with Autokey still on, set a hold keyframe for the pivot point at frame 9.

At frame 10, move the pivot point to the next forward edge. Now you can hop back out of SubObject mode and rotate around the new pivot point. This will make the box look as though it’s rolling up on its edges over the ground.

While switching to SubObject mode can be cumbersome, this is a great way to improve your animation toolset. You can even apply this controller to custom bone or vehicle rigs.

Expert tip When animating the pivot point, use the Stepped animation curve. This allows for making fewer keyframes because you eliminate hold keys.