Offering a look behind some of the math of having a wheel rotate with proper ground contact, CreativMotion’s Cole Wilson shows how to drive (so to speak) the animation with Xpresso.

If you need to animate a wheel rotating, lets say from a car or any other vehicle, having it rigged in such a way that the wheel gets automatically driven is pretty essential. There are wheel setups of varying degrees of difficulty, depending on what you need the animation to do in the end.

In this tutorial we will be looking at the maths behind rotating a wheelCole Wilson – CreativMotion

For example, having a wheel orate while a car is moving back an forth is relatively simple. What happens when you turn the car? That set up becomes a little more complex. In fact to be truly realistic, one wheel in a turn moves at a different rate than the other.

Xpresso to the Rescue

Here, Cole shows who to use a position controller to begin the wheel rig. He shows how to work out the ever important circumference of the wheel to base the math on. Then he continues to show how to drive the wheel based on distance rather than an axis position.

This is done with a range of Nodes in Xpresso, using the Vector to Reals Node, the Distance Node, and the Range Mapper Node to conform and wire a range of values. Cole also takes a look at the bounding box node in Xpresso, showing how it can be used to automatically feed the value of the diameter into the existing Xpress setup.

Going Further: Wheel Rotation Automation in C4D

Of course essential techniques in 3D get revisited quite often. So we have had the luxury of more than one point of view in dealing with how to get a wheel to rotate mathematically using expressions.

Safina 3D had a look at using Xpresso with Thinking Particles to automate wheel rotation in C4D with the post xPresso & Thinking Particles to Automate Wheel Rotation in Cinema 4D.

Roman Armankutsev had a great and in-depth look at rigging an entire car asset in Cinema 4D, which also included how to rig a wheel realistically with the post, Rigging a Car in Cinema 4D Using Xpresso.

Now that you know how to automate the wheel oration, you might want to take a look at modeling a detailed car tire in Cinema 4D, from tutorial author Baron Jepson.