Adding Random Motion

Splitting the jitter and the general motion into separate components makes it a whole lot easier managing your animation.
The first thing to be considered is the structure of the animation. If we apply the judder directly to any of the axis of the object, it will be difficult to control or make changes to the general animation later on in the production. So the idea is to split the jiggling and overall motion into separate components, so they can be controlled independently from one and other. Granted that at a first glance, it might not appear as elegant as with the use of expressions but once you’ve set it up, you’ll se just how much more straightforward and intuitive this approach will be.

Start off by opening your scene or use the shaker scene from the cover CD, and add a Primitive>Polygon Mesh>Cube (any polygon mesh will do). This object is where we’ll be controlling the jitter, so give it a suitable name, click Modify>Deform>Shape Jitter and click on the Lock icon in the Property Editor to keep it open as you probably want to return to it in couple of minutes. The Shape Jitter Operator will randomize the position of each point of the mesh over time, based on the values you enter, which we’ll then use to judder our main object. Select any of the points on the Cube mesh and click Ctrl + L to create a cluster. Now, select your main object and from the Constrain menu click Object to Cluster and pick the newly created cluster on the Cube (use the constraint compensation button, CnsComp, if you want to keep the main object’s current position). Since we’ve just added a constrain to the shaker, it wouldn’t make sense animating the object directly. Instead we’ll add a null object and use this for the overall transformation, so add one to the scene. With the Null still selected, click the Parent button and with the left mouse button pick both the Shaker and the Cube objects.

The shaker will now inherit the clusters randomized position due to the constraint, as well as the Nulls overall motion because of the parent-child relation, but more importantly; they are controlled independently. With the hierarchy completed you can select the Cube and press H to hide it, as we don’t want it to show in the rendered images.

The project files used in this tutorial can be found at:
http://www.Redi-Vivus.com/Caffeineabuse/Adding_Random Motion.zip





















By using the Shape Jitter deformer, you automatically get a clean presentation with sliders for all the parameters needed, and they’re animateble as well.