3D World’s question of the month

The interesting jiggle of jelly isn’t unique to gelatin. Beer bellies, breasts and antennae all make use of the same sort of soft body jiggle that you see in the Jell-O advertisements currently airing in the US. Mastering a technique to produce this effect, then, is an important tool to have in your 3D toolbox.

Having said that, it is important to point out that there are a lot of different approaches to this problem, and we explored several while preparing this tutorial. Among them were Cinema 4D’s Dynamics system and Clothilde, the system in C4D’s optional MOCCA module. Both produce some interesting results and may indeed be the method of choice in other situations. In particular, Clothilde has some great ways of mimicking soft body dynamics with collision detection, with a really simple workflow and a quick output. However, the most effective technique for your jelly problem is C4D’s Soft IK options. Soft IK has been around for a few generations of C4D. In the latest release (R10), it is largely presented as a legacy tool provided for backward compatibility. Let’s hope it never goes away, because it can automate this movement really well.

The core idea is that a string of joints become spring-like. You can define how stiff these springs are and how much they try to retain their shape and regain their rest rotation. If you move the parent joint, however, the child joints have a sort of virtual weight that provides built-in secondary motion.

Like most movement, secondary motion can be stylised, but for something like jiggling gelatin, an automated solution would be of tremendous help. By preparing strings of joints – you can get away with one string per shape, or use multiple strings to various pockets – it’s possible to add a realistic jiggling motion to a form.

The technique we’ve used could be adapted for a fat character by building the joints out from a spine into the belly, buttocks or breasts. The jiggle principles and setup would be the same. Take a look at this setup to explore R10’s implementation of Soft IK and how to allow the built-in dynamics to jiggle your polygons.

Click here to download the resource files (~8MB)