You may be asking why we're making 6 curves when one curve would be enough to have dynamics on it and move around under the control. Well, the answer is as an animator I want some predictability over it. Depending on my settings this curve can move more like a string or more like a rubber hose. If my object is dangling on the end of this dynamic curve it may be able to drift farther while moving in one direction than it could in another. Say the sting his hanging down from the controller. Maybe the object moves twice as far away from the control when moving down than up simply because of the settings and position of the curve. The reason I made a sphere for the control was I wanted some sort of container. We then made 6 curves, because we're going to make this like 6 elastic strings tied to each axis of the sphere and tethered together in the center. So to keep thing predictable and controllable for the animator, the control will do most of the work and since the points are tied together in the center, the object being animated by this rig will never really fly too far past the control. It'll have dynamic motion, but the control still stays the main master of the objects position. In the end, you may not need 6 curves for your needs, this is just what I needed in this case.
After you've built all 6 curves, we're now going to rebuild them. Why? Because dynamic curves need multiple points to bend across. If you use linear curves, they won't bend at all when made dynamic. We simply made them linear because it was the quickest and easiest way to build a straight line. So we'll rebuild them as cubic curves, with multiple points. How many points you make really depend on how much motion and stretch you want out of your final animation. Without getting too in depth on the hair system, basically the more points in your curve, the more it'll stretch.
Next, parent these six curves under the sphere control we made. Depending on your set up needs you could also group the curves and then parent constrain the group to the control.
Now we'll make the curves Dynamic Hair curves. Press the play button and you should see then curves droop down like strings. You'll see that both ends of hair are fixed, and only everything between the ends of the curves move. This isn't quite what we want yet.
So next, we're going to take the new curves that were created (the hair curves) select them and open up the Attribute editor. For each follicle, go in and change the settings from both ends to base. (This is the reason it was important to be consistent in which direction you started and finished each curve.) Hit play again and you'll see the curves droop again, but this time only staying fixed at a single end.
The next task is to attach all the ends of each hair follicle to each other so that we get a single point that drifts around dynamically, but that is also tethered down as not to drift too much.
Scrub your time slider back to zero.
Go up to the hair menu and choose constrain hair to hair.
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