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Animating The Inanimate, Part Three

Handling Handles By Kevin Schmitt
Last time we looked at morph targets as a character animation technique, and by my count, that particular piece contained no less than 57,491 instances of the word "morph." As we press on to the exciting world of handles, it's my personal goal to surpass that number in this article, aiming for a cool 60,000 mentions of "handles." By the end of this series (which will, mercifully, come with the next installment), there will probably be a great many words you will likely wish you've never heard of, but for now, I'll just concentrate on making you sick to death of the word "handles" and all its various derivatives.

First off, let me preface this piece by saying that I don't know if "handles" is even a real term for what I'm about to show you. One of the byproducts of being a freelancer is that I've sometimes found myself developing my very own Nell-like vocabulary for processes that may or may not have perfectly acceptable names in other professional circles, so over time I've taken to calling this particular technique "handles" amongst myself. That said, let's get into the long and the short of what handles are.

The concept of handles refers to the process of taking a model, associating target objects with it, and using the movement of the target objects to control the deformation of the base model. These target objects become, in effect, the handles which you grab in order to deform the associated base model, almost like the way you would use the handles on a marionette to control its movement. In LightWave (which, if you've missed the other articles in this series, is the 3D animation program I'm using), this technique is implemented through a series of plug-ins that, when applied to your base model, allow you to assign target objects to control various movements such as bending, twisting, and tapering (among others). In practice, these target objects will more often than not be null objects, which most, if not all, mainstream 3D packages implement in one form or another.

Thoroughly confused yet by that exemplary definition which was no doubt aided by my awesome command of the English language? Fortunately, I have examples I can turn to here to better illustrate the concept. I'm sure you all remember Mr. Tube from the last article; Mr. Tube surely remembers you. Anyway, he's kindly agreed to join us again today to help me demonstrate handles. Mr. Tube, indeed being a tube, just so happens to be the perfect shape for this example. Let's say that I want to have a looping 30 frame animation of Mr. Tube swaying his "head" around in a circular fashion (fig. 1).

Figure 1: Mr. Tube swaying round and round. He's got the music in him.

To do this particular move using handles, I'll first bring Mr. Tube into the LightWave Layout environment. I'll then add two null objects for the handles, which I'll call n_tophandle and n_bottomhandle (I always preface null objects with "n_," so they're easy to pick out of selection lists and hierarchies and such). Since I know Mr. Tube is exactly one meter high, I'll set my n_tophandle object to have its Y axis position at one meter, and since Mr. Tube's center is actually set to be his bottom plane, I'll leave n_bottomhandle where it is (at coordinates 0,0,0). I'll then parent each handle to the tube object so they'll travel wherever Mr. Tube goes. This base setup is shown in figure 2.

Figure 2: The handles are the turquoise lines framing the top and bottom of the tube. The object hierarchy is shown in the Scene Editor window to the right.

Now comes the fun part. With the tube object selected, I'm going to open up the Item Properties panel, and with the Deform tab active, I'm going to add the Deform:Bend displacement plug-in (fig. 3). I haven't told the plug-in what handles to use yet, so by default it shows up as inactive. That's about to change. Double-clicking on the plug-in name brings up the plug-in configuration box, which I'll tell to use n_tophandle as the effect handle, n_bottomhandle as the effect base, and the Y axis to deform along (fig. 4). Once that's done, the Deform:Bend plug-in reflects these settings in the Item Properties panel (fig. 5). Now that Mr. Tube is set up the way I want him, all I need to do to animate him bending is to select the n_tophandle object and move it around at various points along the timeline. In this case, to make Mr. Tube sway in a circle, I just made keyframes along the timeline for the n_tophandle object's X and Z coordinates, and the top of the tube bends to follow. That's it! Pretty easy, huh?

Figure 3: The Object Properties panel as shown after the Deform:Bend displacement plug-in was first added.

Figure 4: The Deform:Bend plug-in options.

Figure 5: The Object Properties panel, updated to reflect the handles assigned to it.

Of course, as simple as this is conceptually, you can combine several deformation plug-ins with more than two handles to achieve a pretty wide range of motion. Let's once again turn to our old buddy Al the Calculator for a closer look.

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Related Keywords:morph, character, animation, technique, deformation, 3D


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