The flex modifier has been my close friend over many years, and continues to keep me safe when producing animations in a rush. Obviously none of us would want to cut corners when animating (maybe), but this little modifier certainly helps me to do that in the quickest way possible, by creating secondary motion without the hassle of keyframing it.
Secondary animation are those subtle aspects of an animation sequence that add that extra level of believability and professional output. It’s that small wobble on the car aerial or that , which adds to the overall final quality. However these subtleties can often take 80% of the time to implement.
The best way of doing this is via the powerful Flex modifier. (I would even go so far to say this is potentially the king of modifiers!) Find out how below:
1. Animate your primary animation as normal. In the below example I simply did a straight start and stop animation over 100 frames. (The easiest way is to Press ‘N,’ move the timeslider to a new frame number, and then move the object. Press ‘N’ again and your done)
2. Now quickly check your animation by pressing the ‘/’ key or the ‘Play Animation’ icon on your timeline.
3. Now load on a ‘Flex’ modifier onto the object. and once again press play.
4. Nothing happens! OK, there’s a reason for this. The flex modifier uses the speed and distance travelled of the vertices to derive the secondary animation, in this case, the object is moving too slow. so we need to drag the last keyframe so the animation is quicker.
Select the object, then select the last keyframe in the timeline and drag to, say, frame 25. You should now see an immediate difference when you press play again.
5. The beauty of this modifier is it’s simplicity using the defaults, but lets have a look at some of the other options. The modifier is packed full options that allow us to tweak the settings, so lets change the ‘Flex’ settings from the default 1.0 to 10.
6. We should now see more of a jelly-wobble (a technical 3d term), when we playback and review the animation.
7. Another option I regularly rely on is the ‘Samples’ option. This basically reduces the accuracy of the animation. So why would I do this? well its a fast way of drastically increasing the flex’ing effect. So lets change this from the default 5 to 2, and see the resultant effect.
8. Finally the other options left to investigate are the ‘Strength’ and ‘Sway.’ Change these settings and press play, to see what they do.
Hopefully you will agree this is an extremely powerful tool, especially when needing to quickly create some soft-body style animation effects.